Differential expression of CD25 (interleukin-2 receptor) on lamina propria T cells and macrophages in the intestinal lesions in Crohn's disease and ulcerative colitis.

Many interleukin-2 receptor (CD25) bearing cells can be identified by alkaline phosphatase immunohistochemistry in the diseased intestinal lamina propria of children with Crohn's disease or ulcerative colitis, but rarely in normal intestine. In both diseases, the CD25+ cells are present as aggregates in the lamina propria below the epithelium, and constitute a large proportion of the lamina propria mononuclear cells. In Crohn's disease, but not ulcerative colitis, CD25+ cells are abundant in the submucosa. The CD25+ cells in Crohn's disease are 58-88% CD3+, CD4+, CD8-, indicating that they are T cells, whereas in ulcerative colitis the CD25+ cells are greater than 80% CD3-, CD4+, HLA-DR+, indicating that they are macrophages. Thus, differential expression of CD25 on T cells and macrophages serves to distinguish the immunologic lesions in ulcerative colitis and Crohn's disease.     

Lamina propria T cells in Crohn's disease and other gastrointestinal inflammation show defective CD2 pathway-induced apoptosis

BACKGROUND & AIMS: Normal human lamina propria lymphocytes manifest increased unstimulated apoptosis compared with peripheral lymphocytes, which are enhanced after stimulation via the CD2 activation pathway. This activation-induced apoptosis down-regulates cell expansion and cytokine production. In previous studies, it was shown that lamina propria T cells from patients with Crohn's disease and ulcerative colitis manifest abnormal proliferation and cytokine production. It was therefore of interest to determine if such cells also showed abnormal patterns of apoptosis. METHODS: Apoptosis was evaluated by propidium iodide staining of cells followed by flow cytometric analysis. Fas expression and Bcl-2 levels in cells were evaluated by immunofluorescence. RESULTS: Lamina propria lymphocytes from patients with Crohn's disease and ulcerative colitis as well as from 2 patients with diverticulitis showed defective CD2 pathway-induced apoptosis. Studies of the mechanisms of this defect focusing on cells from patients with Crohn's disease showed that Crohn's disease lamina propria lymphocytes from inflamed tissues express the same amount of cell surface Fas but are less sensitive to Fas-mediated apoptosis than control cells. In addition, lamina propria lymphocytes from inflamed Crohn's disease tissues manifest increased expression of Bcl-2 after CD2 pathway stimulation and elevated Bcl-2 levels in cultures of unstimulated T cells. CONCLUSIONS: T cells isolated from areas of inflammation in Crohn's disease, ulcerative colitis, and other inflammatory states manifest decreased CD2 pathway-induced apoptosis. Studies of cells from inflamed Crohn's disease tissue indicate that this defect is accompanied by elevated Bcl-2 levels. These changes are probably caused by the chronic inflammation and may aggravate the underlying disease processes that are present.     

Flow cytometric analysis of peripheral blood lymphocytes in ulcerative colitis and Crohn''s disease.

Using two colour immunofluorescence with fluorescein isothiocyanate and phycoerythrin labelled monoclonal antibodies, multi-parameter flow cytometry was used to examine the antigenic characteristics of peripheral blood lymphocytes in whole blood of patients with ulcerative colitis and Crohn's disease who were not taking immunosuppressive drugs. The numbers of CD4+ and CD8+ lymphocytes in patients with ulcerative colitis and Crohn's disease remained unchanged so that the CD4/CD8 ratio was the same as that of normal control subjects. In Crohn's disease there were many activated T cells (CD3+, CD25+). Although natural killer cells in active Crohn's disease were lower than in normal control subjects, cytotoxic T lymphocytes, as defined by CD3+, CD16+, did not differ in patients with inflammatory bowel disease compared with normal control subjects. For B cell subsets, there were differences in Leu-1+ B cells, Leu-8+ B cells, Fc epsilon R+B cells (Leu-16+, Leu-20+), and activated B cells (Leu-12+, Leu-21+) between patients with inflammatory bowel disease and normal control subjects. These differences are compatible with local activation of B cells in the inflamed colon.     

The importance of peripheral immune cells in inflammatory bowel disease.

Background/aims: Inappropriate down regulation of an activated immune system is considered as the main pathogenetic mechanism in inflammatory bowel disease. Migration of circulating cells to a diseased intestine is considered as an important factor in the pathogenesis of inflammatory bowel disease. We aimed to evaluate some features of circulating immune cells in inflammatory bowel disease. Methods: Twenty-two control, 29 Crohn's disease and 17 ulcerative colitis patients were studied. CD2, CD3, CD4, CD8, CD11b, CD11c, CD25, CD45RA, CD45RO, CD54 and HLA DR on the surface of peripheral blood lymphocytes and CD11b, CD11c, CD45RA and CD45RO on the phagocytes were researched with two-color immunofluorescence flow cytometry. Results: The percentages of CD2+ and CD4+ lymphocytes were found significantly reduced in ulcerative colitis. CD3+ and CD8+ lymphocytes in inflammatory bowel disease were higher than in controls. CD45RA+ lymphocytes were found significantly decreased in ulcerative colitis and active Crohn's disease. CD45RO+ lymphocytes and CD45RO+, CD11b+ and CD11c+ phagocytes were significantly increased in Crohn's disease. Conclusions: We demonstrated that there were significant differences between ulcerative colitis and Crohn's disease in the expression of some important surface markers on the peripheral blood immune cells. It seems that circulating CD11b-CD11c and CD45RA-CD45RO expressing phagocytes are important in inflammatory bowel disease and may be useful in distinguishing Crohn's disease from ulcerative colitis. These findings may give us some clues about the immunopathogenesis of inflammatory bowel disease.     

Expression of the Kp43 (CD 94) receptor by natural killer (NK) cells in ulcerative colitis.

BACKGROUND/AIMS: The presence of natural killer cells in the colon mucosa of patients with ulcerative colitis has not been studied, therefore, the study was designed to investigate the densities of cells expressing CD3+, CD4+, CD8+, CD56+ and the new CD94+ in colon mucosa of active and inactive ulcerative colitis patients. METHODOLOGY: Twenty ulcerative colitis patients, 10 with active disease and 10 with inactive disease, and 10 subjects with a histologically normal rectal mucosa were used as patients and controls. Additionally, a subgroup of 6 patients with active proctitis has been studied. Two biopsy specimens from rectal mucosa were taken for all patients and controls. Two biopsy specimens of proximal colon mucosa of the subgroup of 6 patients were also taken. One biopsy was processed for immunohistochemical studies and another for histologic study. RESULTS: The densities of CD3+, CD16+, CD56+ and CD 94+ were significantly increased in active ulcerative colitis patients compared to inactive subjects (P < 0.001). The increase in the CD4+ and CD8+ was not statistically significant. Patients with inactive ulcerative colitis also presented increased numbers of CD3+, CD56+ and CD94+ cells compared to controls (P < 0.001). In the subgroup of proctitis, the densities of cells expressing all the antigens were significantly lower in the normal mucosa compared to the affected colon (P < 0.001). No differences in the number of lamina propria DC1a+ cells between patients and controls were found. CONCLUSIONS: These findings suggest that natural killer cells are increased in active ulcerative colitis subjects and that the affected mucosa of ulcerative colitis patients with inactive disease is in state of "latent" inflammation. On the other hand, the normal looking mucosa from active ulcerative colitis patients does not differ from the mucosa of control subjects. Therefore, it seems that in ulcerative colitis the immunological alterations are limited to the affected mucosa.     

T lymphocyte subsets in inflammatory bowel disease: peripheral blood

Peripheral blood T lymphocytes and T lymphocyte subsets have been quantified in 28 patients with ulcerative colitis and 26 with Crohn's disease by an indirect immunofluorescence technique using monoclonal antibodies: OKT3, which detects all peripheral blood T lymphocytes; OKT4 (T cells of helper phenotype); and OKT8 (T cells of supressor-cytotoxic phenotype). Eighteen normal subjects and 16 patients with a variety of non-inflammatory gastrointestinal disorders were studied as controls. No significant differences were found between patient and control groups in the proportions of circulating T lymphocytes or their subsets. When compared with normal subjects, absolute numbers of T lymphocytes were reduced in patients with active ulcerative colitis or Crohn's disease (p less than 0.05). OKT4+ T cell numbers were reduced in ulcerative colitis, whether active (p less than 0.02) or inactive (p less than 0.05) and in active Crohn's disease (p less than 0.05) Numbers of OKT8+ T cells were reduced in active Crohn's disease (p less than 0.01). There were no differences in T lymphocyte numbers between the patient groups and the disease control subjects. The OKT4+:OKT8+ ratio in patients with inflammatory bowel disease did not differ from that in controls. No relation was found between any of the parameters studied and disease activity, site, or extent of disease, or treatment with sulphasalazine or corticosteroids. The presence of Ia-like, HLA-DR antigens on T cells was detected using a double marker immunofluorescence technique. In control subjects up to 7% of OKT3+ cells were HLA-DR+. In only three patients was the proportion of HLA-DR+ cells greater than in controls. These results indicate that the pathogenesis of ulcerative colitis or Crohn's disease does not depend upon an alteration in the proportion of circulating T lymphocytes nor upon an imbalance of T lymphocyte subsets as defined by monoclonal antibodies. The reduction in T lymphocyte numbers may result from mucosal infiltration. The findings also suggest that circulating T lymphocytes are not activated.     

Loss of interleukin-2-producing intestinal CD4+ T cells in inflammatory bowel disease.

Interleukin-2 activity of intestinal lamina propria mononuclear cells is decreased in Crohn's disease and ulcerative colitis patients compared with control patients with noninflammatory bowel disease. Factors that might be responsible for this phenomenon were investigated. Most interleukin-2 activity was produced by helper (CD4+) T cells. These were present in comparable numbers in both inflammatory bowel disease and control cultures, but the frequency of interleukin-2-producing cells was significantly (3-4 times) lower among Crohn's disease and ulcerative colitis than control cells. In agreement with this finding, levels of interleukin-2 messenger RNA were substantially decreased in both forms of inflammatory bowel disease compared with controls. Mucosal CD8+ T cells and plastic-adherent cells were unable to suppress interleukin-2 activity by autologous or allogeneic CD4+ T cells. The rate of interleukin-2 absorption was similar for inflammatory bowel disease and control cells. Induction of interleukin-2 by different stimuli (phorbol ester, phytohemagglutinin, or anti-CD3 monoclonal antibody) before or after incubation under basal conditions ("resting") failed to normalize the capacity to generate interleukin-2 by Crohn's disease and ulcerative colitis cells. Prostanoids (prostaglandin E2 and 6-keto-prostaglandin F1 alpha) were produced in large amounts in cultures of inflammatory bowel disease cells, but inhibition by indomethacin failed to restore interleukin-2 activity to control levels. Finally, supernatants from Crohn's disease and ulcerative colitis cell cultures failed to suppress interleukin-2 production by control CD4+ T cells. Our results show that the low interleukin-2 activity detected in inflammatory bowel disease mucosa is not caused by activated suppressor cells, excessive lymphokine utilization or immune stimulation, a defective response to activation signals, or production of inhibitory substances. Rather, the low interleukin-2 activity appears to be related to a loss of interleukin-2-producing mucosal CD4+ T cells. It is concluded that abnormalities of intestinal CD4+ T-cell function are associated with the immunopathogenesis of Crohn's disease and ulcerative colitis.     

Antigen induced suppression in peripheral blood and lamina propria mononuclear cells in inflammatory bowel disease.

Using an autologous system, suppressor cell function to a range of mycobacterial antigens and Kunin antigen of peripheral blood mononuclear cells and lamina propria lymphocytes has been investigated in normal subjects and patients with inflammatory bowel disease. In the peripheral blood there was reduced antigen induced suppression in patients with Crohn's disease in remission to Mycobacterium paratuberculosis, purified protein derivative (PPD), M fortuitum, and Kunin antigens (p less than 0.05). In patients with ulcerative colitis in remission there was reduced antigen induced suppression in the peripheral blood to Kunin antigen (p less than 0.001), M avium (p less than 0.01), M nonchromogenecin, and M fortuitum (p less than 0.05). The phenomenon of antigen induced suppression was largely CD8 dependent, as depleting CD8+ cells reduced the effect and the concentration of soluble CD8 in the culture supernatant was directly related to the suppressor index (r = 0.25, p less than 0.05). These results are likely to be a true reflection of the cell mediated response to antigen as patients with a positive Mantoux skin test have a significantly higher suppressor index to PPD than Mantoux negative subjects (p less than 0.05). These findings may have significance in the aetiopathogenesis of inflammatory bowel disease. However, a similar effect could not be shown in the lamina propria lymphocytes of patients having colectomy for active disease.     

Two-color immunofluorescence and flow cytometric analysis of lamina propria lymphocyte subsets in ulcerative colitis and Crohn's Disease

By using two-color immunofluorescence with fluorescein isothiocyanate (FITC) and phycoerythrin (PE)-labelled monoclonal antibodies and multiparameter flow cytometry, we investigated lamina propria lymphocyte subsets of patients with ulcerative colitis (UC) and Crohn's disease (CD). Leu-3/Leu-2 (CD4/CD8) ratio of lamina propria lymphocytes (LPL) of CD (mean±sd: 1.9±0.8,P<0.01) was significantly decreased compared with controls (3.3±1.1), because of an increased number of CD8+lymphocytes. The majority of lamina propria CD4+cells were CD4+, Leu-8-and CD4+, CD45R-both in controls and IBD tissue. Many lamina propria T lymphocytes were activated, expressing HLA-DR antigen not only in IBD but also in controls. NK cells defined by CD16 and CD 56 (3.0±1.4%,P<0.01) were significantly decreased in patients with UC compared with controls (6.5±3.0%). A low proportion of B cells in the intestinal mucosa expressed Leu-8 antigen and CD23 antigen. The proportion of activated B cells of LPL was high in IBD mucosa as well as normal mucosa. These findings suggest that local activation of B cells leads to the loss of the expression of Leu-8 antigen and CD23.     

CD4+NKG2D+ T cells in Crohn's disease mediate inflammatory and cytotoxic responses through MICA interactions

BACKGROUND & AIMS: Crohn's disease (CD) is an inflammatory bowel disease characterized by uncontrolled immune responses to bacterial flora, with excessive activation of T lymphocytes. MICA is a stress-induced major histocompatibility complex-related molecule expressed on normal intestinal epithelial cells (IECs) and recognized by the NKG2D-activating receptor on CD8(+) T cells, gammadelta T cells, and natural killer cells. We examined the role of MICA-NKG2D interactions in the activation of T lymphocytes in CD. METHODS: MICA expression was analyzed by flow cytometry on IECs isolated from patients with active inflammatory bowel disease and controls. NKG2D expression and function were analyzed on lamina propria and peripheral blood lymphocytes. RESULTS: MICA expression was significantly increased on IECs in CD, with higher expression in macroscopically involved areas. A subset of CD4(+) T cells expressing NKG2D was increased in the lamina propria from patients with CD compared with controls and patients with ulcerative colitis. CD4(+)NKG2D(+) T cells with a Th1 cytokine profile and expressing perforin were increased in the periphery and in the mucosa in CD. CD4(+)NKG2D(+) T-cell clones were functionally active through MICA-NKG2D interactions, producing interferon-gamma and killing targets expressing MICA. IECs from patients with CD had the ability to expand this subset in vitro. CD4(+)NKG2D(+) lamina propria lymphocytes from patients with CD highly expressed interleukin-15R alpha, and interleukin-15 increased NKG2D and DAP10 expression in CD4(+)NKG2D(+) T-cell clones. CONCLUSIONS: These findings highlight the role of MICA-NKG2D in the activation of a unique subset of CD4(+) T cells with inflammatory and cytotoxic properties in CD.     

Expression of CD45RO on circulating CD19+ B-cells in Crohn's disease.

Crohn's disease is an immunoregulatory disorder of the intestine that can be associated with systemic manifestations. This study analysed B-cell differentiation antigens to identify B-cell subpopulations unique to patients with Crohn's disease. CD45 isoform expression was used as an indicator of B-cell differentiation stage. This work shows that B-cells in blood and gut of patients with Crohn's disease are at an advanced stage of differentiation based on their unusual presentation of transitional (RA+ RO+) and late stage (RO+)CD45 isoforms on lamina propria lymphocytes, whereas normal intestinal lamina propria lymphocytes B-cells express primarily CD45RA. Crohn's disease patients had heightened expression of the CD45RO isoform on CD19+ lamina propria lymphocytes, and was found in a statistically significant proportion of Crohn's peripheral blood mononuclear cells (PBMC) where CD19+ PBMC had an expression pattern affecting an unexpectedly high proportion of these differentiated or late stage CD45RO+ B-cells. The expression of CD45RO varied greatly among CD19+ PBMC from patients with Crohn's disease, so multiple regression analysis was performed between these CD45 isoforms and several clinical parameters. After grouping high and low CD45RO expression on CD19+ B-cells, a significant statistical difference was found between high Crohn's disease activity index (CDAI) and low CDAI Crohn's disease patients respectively.     

Distribution of T cell subsets and DR antigen positive T cells in peripheral blood and in intestinal mucosa of inflammatory bowel disease

The absolute number of T cell subsets and the rate of T cell DR antigen expression in the peripheral blood and the intestinal mucosa in IBD patients were compared with those in healthy normal controls by two color analysis. The methods used here were flow cytometry for the peripheral blood and immunohistological fluorescent staining for the intestinal mucosa. In peripheral blood lymphocyte (PBL), helper (CD4+ Leu8-) T cells increased in ulcerative colitis (UC), whereas suppressor (CD8+ CD11+) T cells decreased in Crohn's disease (CRD). In lamina propria lymphocyte (LPL) of intestinal mucosa, there were no changes in the proportion of T cell subsets in UC, whereas suppressor (CD8+ CD11+) T cells increased in inflamed mucosa of CRD. DR antigen positive T cells did not increase in PBL, but they increased in LPL of both UC and CRD. In conclusion, there are some differences in distribution of T cell subsets and DR antigen positive T cells between the peripheral blood and the intestinal mucosa in IBD patients. Moreover, the heterogeneity of the distribution of T cell subsets is observed between UC and CRD.     

Increased activation of isolated intestinal lamina propria mononuclear cells in inflammatory bowel disease

Normal human lamina propria lymphocytes are in a heightened state of activation compared with peripheral blood with regard to cell-surface activation antigen expression (transferrin receptor, interleukin-2 receptor, 4F2) and the increased spontaneous secretion of immunoglobulins in vitro. This study evaluates the cell-surface expression of activation-associated antigens in different subpopulations of isolated colonic lamina propria mononuclear cells in inflammatory bowel disease. In pilot studies using three-color flow cytometry, autofluorescence was observed that was emitted by unstained lamina propria mononuclear cells, which interfered with both the sensitivity and the specificity of the analyses. Because a major portion of the intestinal lymphocyte populations of interest were autofluorescent, a method to remove autofluorescence signals was developed by designing a computer program for the subtraction of autofluorescence from the emissions of each individual cell. This technique increases both the sensitivity and specificity of flow-cytometric analyses of intestinal lamina propria mononuclear cells. Using fluorescence-activated cell-sorter analyses with subtraction of autofluorescence on a single-cell basis, increased expression of lymphocyte activation antigens (interleukin-2 receptor, transferrin receptor, 4F2) was found on the cell surface of isolated intestinal B cells, T cells, CD4+ T cells, and CD8+ T cells in both Crohn's disease and ulcerative colitis. Therefore, markedly increased intestinal lymphocyte activation is a major immunological alteration in inflammatory bowel disease and includes all lymphocyte subpopulations investigated in this study. In addition, 5-aminosalicylic acid, which is used for the treatment of intestinal inflammation in inflammatory bowel disease, inhibits the expression of cell-surface activation antigens on mitogen-activated peripheral blood lymphocytes in a dose-dependent manner. These observations suggest that lymphocyte activation may play an important role in underlying immune processes that lead to chronicity and perpetuation of inflammatory bowel disease and may implicate an additional mechanism for the therapeutic action of 5-aminosalicylic acid.     

Phenotypic analysis of lamina propria lymphocytes. Predominance of helper-inducer and cytolytic T-cell phenotypes and deficiency of suppressor-inducer phenotypes in Crohn's disease and control patients

To better define the nature of intestinal T cells, the phenotypes of isolated lamina propria lymphocytes (LPL) were determined in both Crohn's disease patients and control patients using combinations of monoclonal antibodies that have been found to correlate with particular immunoregulatory functions. Isolated LPL and autologous peripheral blood lymphocytes (PBL) were stained with multiple combinations of monoclonal antibodies and studied by dual immunofluorescence flow cytometry. In LPL, compared with PBL, there was a significant increase in the proportion of T cells having the Leu-3+, Leu-8- and Leu-3+, 2H4- phenotypes (associated with helper-inducer function) and a corresponding decrease in the proportion of T cells having the Leu-3+, Leu-8+ and Leu-3+, 2H4+ phenotypes (associated with suppressor-inducer function). It was also found that in LPL, compared with PBL, the percentage of cells with the Leu-2+, Leu-15+ phenotype (associated with suppressor-effector function) was significantly lower. However, the percentage of T cells with the Leu-2+, 9.3+ phenotype (associated with cytolytic function) was similar in PBL and LPL in control patients. There were no major differences comparing Crohn's disease patients with control patients, except that the proportion of Leu-2+, 9.3+ lymphocytes was higher in PBL in Crohn's disease patients. These results show that the lymphocyte subpopulations in the lamina propria differ from those in peripheral blood in having predominantly the phenotypes of helper-inducer and cytolytic T cells, whereas the phenotypes of suppressor-inducer cells and activated suppressor cells are less frequently observed.     

CD44 isoform expression on colonic epithelium mediates lamina propria lymphocyte adhesion and is controlled by Th1 and Th2 cytokines

BACKGROUND AND AIMS: CD44v6 and CD44v3 are expressed on the surface of colonic epithelial cells in ulcerative colitis to a much greater extent than in Crohn's disease. We investigated mediators that induce CD44v6 and CD44v3 expression on colonic epithelium and the potential role of CD44 in mediating leucocyte-epithelial adhesion. DESIGN AND METHODS: HT-29 cells were exposed to a range of T-helper 1 and T-helper 2 cytokines. Flow cytometry was used to determine their effect on CD44 isoform expression. The adhesion of peripheral blood and lamina propria lymphocytes to HT-29 monolayers was assessed and the effect of induction and blocking of CD44 isoforms was investigated. RESULTS: Treatment of HT-29 cells with IL-4 and IL-13 resulted in a two- to three-fold increase in membrane expression of CD44v6 and CD44v3 isoforms. This was inhibited by T-helper 1 cytokines and hydrocortisone (P < 0.001). IL-4 increased lymphocyte adhesion to HT-29 monolayers approximately two-fold (P < 0.01). This increased adhesion of both lamina propria leucocytes and peripheral blood lymphocytes was abolished by anti-CD44v6 monoclonal antibodies (P < 0.01 and P < 0.05, respectively). CONCLUSION: IL-4 and IL-13 are potent inducers of CD44v6 and CD44v3 expression on colon epithelial cells. The reciprocal effects of T-helper 2 and T-helper 1 cytokines on CD44 isoform expression may explain the observed differences between ulcerative colitis and colonic Crohn's disease. We have identified increased adhesion between lymphocytes and colon epithelial cells caused by IL-4-induced CD44v6 expression. This may contribute to epithelial targeting of inflammation in ulcerative colitis.     

Immunohistochemical analysis of colonic mucosa with ulcerative colitis--activation of lymphocytes and expression of ICAM-1 by lamina propria dendritic cells and macrophages]

The colonic mucosa of 30 patients with ulcerative colitis was analyzed by an immunohistochemical technique. A quantitative evaluation for lymphocyte subsets show significantly increased numbers of CD3+, CD4+, CD8+, and CD28+ cells in ulcerative colitis cases of histological grades 3, 4 and 5 by Matts' classification comparing to normal control cases. CD4/CD8 ratio in each histological grade of ulcerative colitis was not significantly different from those in normal controls and disease controls (infectious colitis cases). However, CD28/CD3 ratio was increased significantly in ulcerative colitis cases of histological grades 3, 4 and 5 comparing to control cases. Most of the lymphocytes were positive for lymphocyte function-associated antigen-1 alpha (LFA-1 alpha). There were increased numbers of S100-beta + dendritic cells and CD68+ macrophages in the luminal area of the lamina propria. Moreover double stainings revealed that most of the S100-beta + dendritic cells and CD68+ macrophages were intercellular adhesion molecule-1 (ICAM-1, a ligand for LFA-1) positive. These findings suggested that the expression of ICAM1 on S100-beta + dendritic cells and CD68+ macrophages is important by the interaction with T cells and T cell antigen recognition.     

The proportion of CD40+ mucosal macrophages is increased in inflammatory bowel disease whereas CD40 ligand (CD154)+ T cells are relatively decreased, suggesting differential modulation of these costimulatory molecules in human gut lamina propria

BACKGROUND: Signal transduction through binding of CD40 on antigen-presenting cells and CD40 ligand (CD154) on T cells appears to be crucial for mutual cellular activation. Antibodies aimed at blocking the CD40-CD154 costimulatory pathway dampen the severity of experimental colitis. To elucidate the microanatomical basis for signaling through this costimulatory pathway in human inflammatory bowel disease, we studied in situ the cellular distribution of these 2 molecules on lamina propria macrophages and T cells, respectively. METHODS: Colonic specimens from 8 patients with ulcerative colitis and 8 with Crohn's disease, 8 small bowel specimens of Crohn's disease, and histologically normal control samples (6 from colon and 6 from small bowel) were included. Multicolor immunofluorescence in situ staining was performed to determine the percentage of subepithelial macrophages expressing CD40 and that of lamina propria T cells expressing CD154 while avoiding cells in lymphoid aggregates. RESULTS: The proportion of subepithelial CD40CD68 macrophages was significantly increased in normal colon compared with normal small bowel and showed further elevation in both colon and small bowel afflicted with inflammatory bowel disease. In addition, on a per-CD68-cell basis, CD40 expression was significantly increased in severely inflamed compared with moderately inflamed colonic specimens. Conversely, the proportion of CD154 T cells was similar in colon and small bowel, and interestingly, it was significantly reduced in colonic inflammatory bowel disease. CONCLUSIONS: Our findings suggested that modulation of CD40 expression by subepithelial macrophages and CD154 by lamina propria T cells is inversely modulated in the human gut.     

Phenotypes and spontaneous immunoglobulin production in mononuclear cells suspensions isolated from colonic biopsies of patients with mild active and quiescent ulcerative colitis

Lamina propria mononuclear cells can be isolated from mucosal specimens of human colon. In the present study, we have explored whether both the phenotypes and functional properties can be studied in lamina propria mononuclear cell suspensions isolated from the same set of endoscopic biopsies in patients with ulcerative colitis. The counts of CD11b+ lamina propria mononuclear cells in mild active ulcerative colitis were significantly higher than those of both quiescent ulcerative colitis and controls. Similarly, the CD16+ and the CD19+ lamina propria mononuclear cells were significantly increased in mild ulcerative colitis patients in comparison to both quiescent ulcerative colitis and control lamina propria mononuclear cells. Lamina propria mononuclear cells from all the biopsy samples appeared to produce detectable amounts of immunoglobulins of the three classes. The production of IgG in mild ulcerative colitis cultures was significantly higher than that observed in quiescent ulcerative colitis and controls. In contrast, the production of IgA in active ulcerative colitis lamina propria mononuclear cell cultures appeared to be significantly lower than that of both quiescent ulcerative colitis and controls. This study shows that morphology, phenotypes, and functional properties can be assessed in lamina propria mononuclear cell suspensions obtained from the same set of endoscopic biopsy samples. We have also shown that changes in phenotypes and functional status of lamina propria mononuclear cells occurred in mild active ulcerative colitis while no significant abnormality of these parameters was found in quiescent ulcerative colitis. This indicates that a normalization of mucosal immune functions occurs in ulcerative colitis patients when complete clinical and histological remission is achieved.     

Immunohistochemical characterization, distribution, and ultrastructure of lymphocytes bearing T-cell receptor gamma/delta in inflammatory bowel disease

Phenotypic characterization and distribution of gamma/delta T lymphocytes in the intestinal mucosa were investigated in ulcerative colitis and Crohn's disease by immunohistochemistry. The ratio of delta(+) cells to CD3(+) cells in the intraepithelial space of colon was decreased in Crohn's disease (13%) and strikingly decreased in ulcerative colitis (8%) compared with the control (36%). Delta(+) cells in the lamina propria were also decreased, particularly in the distal ileum of Crohn's disease (4%), compared with the control (15%). On the contrary, the cells gathered at the severe inflammatory sites with other inflammatory cells, including beta(+) cells, and were densely distributed in the T-cell zone around lymphoid follicles. Phenotypic characterization showed that delta(+) lamina proprial lymphocytes of colon were mainly CD4(-)CD8(-) in the control (80%) and Crohn's disease (59%). However, in ulcerative colitis, CD4(-)CD8(-) delta(+) lymphocytes were rarely found (3%). This reflects the difference of immunologic background between the two diseases. Immunoelectron microscopically, these cells in inflammatory bowel disease were rich with vesicular structures in cytoplasms, whereas those in the control group contained electron-opaque granules. The decrease and the morphological change may be closely related to the weakness of mucosal defense.     

A comparison of the expression of lymphocyte activation markers in blood, bronchial biopsies and bronchoalveolar lavage: evidence for an enrichment of activated T lymphocytes in the bronchoalveolar space.

In this study healthy never-smoking subjects (n = 18) were recruited from a population study. Bronchoalveolar lavage (BAL), blood lymphocytes and bronchial biopsies, analysed both in the epithelium and lamina propria, were stained for T and B lymphocytes, natural killer (NK) cells and different subpopulations of T lymphocytes. In BAL, significantly higher proportions of T lymphocytes (CD3), T lymphocyte activation markers; HLA-DR, CD26+, CD49a+, CD54+ and CD69+, helper T (CD3+4+) and memory helper T lymphocytes (CD4+45RO+29+) and memory T lymphocytes (CD3+45RO+) were found, compared to blood. However, the proportion of IL-2 receptor-positive T lymphocytes (CD25+) was lower in BAL than in blood. A previously described higher ratio of CD3+4+/CD3+8+ in BAL than in blood (3.4 vs 1.7; P = 0.001) was confirmed. In bronchial biopsies, we found significantly higher numbers of CD8+ cell profiles per mm2 in the epithelial compared to the lamina propria compartment. We conclude that healthy never-smoking men have higher levels of activated memory T lymphocytes in BAL than in blood, and that the T-cell subpopulations differ in the epithelial compared to the lamina propria compartment in the bronchial mucosa and these compartments should be analysed separately. It is reasonable to think that there is a gradient from blood to the airway lumen where T cells are recruited from blood to take part in the defense towards damaging agents.