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.     

Selective expression of CD45 isoforms defines CALLA+ monoclonal B-lineage cells in peripheral blood from myeloma patients as late stage B cells.

The peripheral blood lymphocytes from 42 patients with multiple myeloma (MM) and 13 patients with monoclonal gammopathy of undetermined significance (MGUS) were studied by three-color immunofluorescence (IF) using antibodies directed to a broad range of B-cell markers (CD19, CD20, CD21, CD24), CALLA (CD10), PCA-1 (a plasma cell marker), and to the high and low molecular weight isoforms of the leukocyte common antigen, CD45RA (p205/220) and CD45RO (p 180). CD45RA is expressed on pre-B and B cells, and a transition from CD45RA to CD45RO defines differentiation towards plasma cells. Peripheral blood mononuclear cells (PBMC) from patients with myeloma included a large subset of B-lineage cells (mean of 39% to 45%) that were CALLA+ and PCA-1+ in all patients studied, including newly diagnosed patients and patients undergoing chemotherapy. Southern blot analysis indicated the presence of monoclonal Ig rearrangements in PBMC and a substantial reduction in the germ-line bands consistent with the presence of a large monoclonal B-cell subset. Avoidance of purification methods involving depletion of adherent cells was essential for detection of the abnormal B cells. Phenotypically, this abnormal B-cell population corresponded to late B or early pre-plasma cells (20% to 80% of PBMC), as defined by the concomitant expression of low densities of CD19 and CD20, moderate densities of CALLA and PCA-1, and strong expression of CD45RO on all B cells, with weakly coexpressed CD45RA on a small proportion. Heterogeneity in the expression of CD45RA and CD45RO within the abnormal B-cell population from any given patient suggested multiple differentiation stages. Abnormal B cells similar to those in MM were also detected in MGUS, although as a lower proportion of PBMC (26%). Abnormal B cells from patients with MGUS expressed predominantly the CD45RO isoform, but had a lower proportion of CALLA+ and PCA-1+ cells than were found on B cells from MM. This work indicates that the large subset of circulating monoclonal B lymphocytes from myeloma patients are at a late stage in B-cell differentiation, continuously progressing towards the plasma cell stage.     

B-lymphocytes in CLL and NHL differ in the mRNA splicing pattern of the CD45 molecule

In the present study the cell surface expression of CD45 isoforms on normal and neoplastic human B cells was correlated with splice products of the CD45 mRNA, using RT-PCR technology. In non-Hodgkin's lymphoma cells in the leukemic phase (NHL) the majority of the cells expressed a high level of CD45RA, while in CLL most of the cells expressed a low level. In the Raji and Daudi Burkitt B-cell lymphoma lines the main CD45 mRNA product was the largest, unspliced, full-length isoform (456) and the 56 splice product. Similar results were obtained with B-cell lymphoma cells isolated from the peripheral blood of patients with NHL in the leukemic phase. In EBV-transformed B-cell lines, the 456 and the 56 isoform of CD45 mRNA were predominant, but in addition a low level of the 5- and 0-exon splice products was detected. A strikingly different pattern was obtained with B-CLL cells. In CLL the level of the 456 and the 56 isoforms was low, while that of the 5- and 0-exon splice products was increased. Thus, in contrast to the heterogeneity in the expression of CD45RO in B-CLL, the majority of the cells contained the CD45 mRNA splice product coding for CD45RO. Analysis of splice products of the CD45 mRNA may serve as an additional tool to differentiate CLL from the leukemic phase of NHL.     

Hyposialated 185 kDa CD45RA+ molecules attain a high concentration in B lymphoma cells and in activated human B cells

Alternate splicing of exons of the CD45 molecule generates multiple isoforms differing in their molecular weights (MWs). In B-lymphocytes the CD45RA isoform was previously shown to be expressed on glycoproteins with MWs of 220 and 205 kDa, while the CD45RO isoform was expressed on glycoproteins with MW of 180 kDa. The present study demonstrated that B cell lymphomas and activated B-cells contain CD45 molecules with a MW of 185 kDa that express the CD45RA and CD45RC specificities but neither the CD45RB nor the CD45RO specificities. 185 kDa CD45RA+ molecules were detected in B cell lymphoma B lines, in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines, and in tonsillar B cells, but not in normal, unstimulated peripheral blood B cells. These molecules were not detected in neoplastic and normal T cells. CD45RA+ 185 kDa molecules were present in B cells from three non-Hodgkin's patients in leukemic phase were not detected in B lymphocytes of seven of nine CLL patients tested. Trypsin treatment eliminated only 220 kDa CD45RA+ molecules but not 185 kDa CD45RA+ molecules, indicating that the 185 kDa CD45RA+ molecules are not expressed on the cell surface. Pulse-chase experiments, and studies on the effects of tunicamycin, neuraminidase and O-glycosidase, indicated that the 185 kDa molecules are partially glycosylated CD45RABC molecules that constitute precursors of the 220 kDa molecules. The high concentration of 185 kDa CD45RA+ molecules in B lymphoma cells and in activated B cells seems to reflect a high turnover of CD45RA+ molecules characteristic for these cells.     

Altered expression of CD45 isoforms in differentiation of acute myeloid leukemia.

Specific expression of different CD45 isoforms can be seen in various stages of differentiation of normal nucleated hematopoietic cells. Association of membrane expression of CD45 isoforms and differential levels of leukemia cells was studied in 91 cases with de novo acute myeloid leukemia (AML). Membrane expression of CD45RA and CD45RO was analyzed by flow cytometry and their expression patterns were compared with AML subtypes classified according to the French-American-British (FAB) classification. CD45RA was essentially expressed in all of the FAB myelocytic subtypes (M0-M3). Its expression in percentage was lower in the most differentiated subtype of AML (M3) when compared with other myelocytic subtypes. CD45RO expression was rarely observed in cases with myelocytic subtypes (1/56 cases of M0, M1, M2, and M3) except for the minimally differentiated myelocytic subtype (M0) or those with potential for differentiation to T-cell lineage where three of 12 cases showed CD45RO expression. When leukemia cells of an M3 case were differentiated to mature granulocytes by treatment of all-trans-retinoic acid, they showed increasing expression of CD45RO. In subtypes with a monocytic component (M4 and M5), both of CD45RA and CD45RO expression were observed and mutually exclusive. When 10 cases of M5 were subdivided by the differential level into undifferentiated (M5a) and differentiated monocytic leukemia (M5b), expression of CD45RA and CD45RO was strictly restricted to cases with M5a and M5b, respectively. These results suggest that CD45 isoform expression in AML characterizes differential levels both in myelocytic and monocytic lineages and specifically disturbed in each subtype. The assessment of CD45 isoform expression appears to provide an insight on biological characteristics and a useful supplementary test for differential diagnosis of AML subtypes.     

Heterogeneity of the human CD4+ T-cell population: two distinct CD4+ T- cell subsets characterized by coexpression of CD45RA and CD45RO isoforms

Activation of unprimed CD4+CD45RA+/RO- T cells results in a gradual loss of CD45RA expression concomitant with the acquisition of CD45RO. It has been suggested that this conversion occurs in vivo through a CD45RAbright/RObright stage. Next to this small CD45RAbright/RObright subset (Dbright), a larger subpopulation that expresses both RA and RO isoforms at low levels (Ddull) can be found in the circulating CD4+ T- cell population of all donors. The properties of the latter population are largely undefined. Here, we show that Ddull cells have an intermediate phenotype for antigens such as CD31, CD621, CD58, and CD95 that are differentially expressed on unprimed versus primed T cells. In addition, they are able to provide help for B-cell differentiation and contain substantial numbers of tetanus toxoid (TT)-specific precursor cells. Remarkably, both intracellular cytokine staining and analysis of T-cell clones showed that Ddull cells and CD45RO+ T cells produce comparable high amounts of both interferon (IFN)-gamma and interleukin (IL)-4, which clearly distinguishes them from CD45RA+ and Dbright T cells. Finally, prolonged culture of sorted Ddull cells in a mixture of IL-2, IL-6, and tumor necrosis factor (TNF)-alpha showed that about half of the population retained the Ddull phenotype. Part of the cells upregulated the CD45RA isoform, whereas only a minority switched to single CD45RO expression. Our findings indicate that the Ddull population contains primed T cells, some of which may reacquire an "unprimed" phenotype in the absence of antigenic stimulation.     

Sequential maturation stages of monoclonal B lineage cells from blood, spleen, lymph node, and bone marrow from a terminal myeloma patient.

In order to fully understand the complexity of the monoclonal B lineage cells in multiple myeloma, it is necessary to evaluate the extent to which these cells are resident in solid lymphoid tissues and the phenotypic differences and similarities as compared to the circulating or bone marrow derived B lineage cells. Peripheral blood mononuclear cells from a patient with multiple myeloma were obtained 8 and 3 days prior to death, and mononuclear cells from lymph nodes, spleen, and bone marrow were obtained at autopsy. Rapid changes in the stage of differentiation of blood late-stage B lineage cells towards mature end-stage plasma cells were observed during the last week prior to death. Lymphoid cells within the blood comprised very few T cells, sub-normal numbers of monocytes, and 80% of B lineage cells which were at a late stage of differentiation. Shortly before death, plasma cells were found in the peripheral blood, indicating progression to plasma cell leukemia. At autopsy, the monoclonal B lineage cells in lymph node, spleen, and bone marrow represented different stages of terminal B cell differentiation. In each tissue, the B lineage cells were at an earlier differentiation stage, as defined phenotypically, than the circulating B lineage cells found in blood 3 days prior to death. Analysis of B cell markers and CD45 was used to define the differentiation stage of the relevant B cell populations, revealing a series of differentiation stages. The least mature B lineage cells (CD45hi) were found in lymph node. However, the CD45 isoform expressed was CD45R0, unlike most normal lymph node B cells. More differentiated B lineage cells (CD45med) were found in the bone marrow, and three sequential stages of pre-plasma cells were found in the spleen (CD45bright, CD45moderate, and CD45low-neg), all of which were CD45R0+. The B cells in normal spleen and bone marrow are CD45RA+. The presence of monoclonal B lineage cells in spleen was confirmed by Southern blotting. The B lineage cells from peripheral blood 3 days prior to death were approaching an end-stage plasma cell stage (CD45low/-). On B lineage cells from the various myeloma tissues, a concomitant loss of CD11b and increasing density of CD29 were observed as a function of progression to terminally differentiated stages.     

A flow cytometric assay of CD34-positive cell populations in the bone marrow

Summary CD34⁺ BM cells form a heterogenous population of primitive stem cells and more mature progenitors committed to different lineages of differentiation. By combining CD45 expression with SSC, it is possible to separate immature cells from more diferentiated BM cells, and, by three-colour flow cytometry, analyse the antigens expressed in various subsets of cells. In this paper we show that in the normal BM at least four distinct CD34⁺ cell populations can be identified by their different patterns of CD45 expression and SSC. The most immature CD34⁺ cell population (0.1% of the BM cellularity) lacked all signs of lineage commitment and was CD45RA negative and only weakly CD45 positive. With increasing expression of the CD45 antigens, a second CD34⁺ population (0.2% of the BM cellularity) was formed expressing mainly primitive lymphatic antigens. However. 30% of the cells co-expressed B-cell line antigens and myeloid antigens. Cells committed to the myeloid cell line lost B-cell line antigens, gained CD45 antigen expression and SSC and formed two CD34⁺ cell population (0.2% and 0.1% of the BM cellularity. respectively) differing only with respect to the pattern of myeloid antigen expression and SSC characteristics. Similarly, differentiation along the lymphatic pathway implicated down-regulation of myeloid antigens, loss of the stem cell antigen and immature lymphatic antigens and gain of CD45 expression and mature lymphatic antigens.     

Expression of the leucocyte common antigen (LCA,CD45) isoforms RA and RO in acute haematological malignancies: possible relevance in the definition of new overlap points between normal and leukaemic haemopoiesis

Summary. The membrane expression of CD45RA and CD45RO on fresh leukaemic cells taken from 529 cases of acute haemopoietic malignancies, including 117 B-origin acute lymphoblastic leukaemia (B-origin ALL), 3 7 T-origin acute lymphoblastic leukaemia (T-origin ALL), 297 de novo acute myeloid leukaemia (AML), 42 refractory anaemia with excess of blasts in transformation (RAEB-T) and 36 myeloid blastic phase of chronic myelogenous leukaemia (CML-BP-my), was analysed. B-origin ALLs were characterized by the lack of the RO isoform along with the consistent presence of RA. Conversely, a differential expression of the two isoforms was detected in different subsets of T-origin ALL, in that T-stem cell leukaemias (T-SCL: CD7⁺, CD4^?, CD8^?, CD1^?) preferentially expressed CD45RA whereas conventional T-acute lymphoblastic leukaemias (T-ALL: CD7⁺, CD4⁺ and/or CD8⁺ and/or CD1+) were consistently marked by CD45RO. Within myeloid malignancies, most of AMLs displayed CD45RA, while a substantial group of CML-BP-my preferentially exhibited CD45RO. As a general rule, a reciprocal exclusion of the two isoforms was observed in AML as well as in ALL. Nevertheless, a frequent coexpression of CD45RA and CD45RO was observed in CD14⁺ AML. In vitro treatment with all-trans retinoic acid (ATRA) was able to promote a switch from CD45RA to CD45RO expression in 2 7 de novo AML, independently from morphological subtyping. To our knowledge, this is the first report on CD45 isoform expression in a large series of patients with acute leukaemia. The knowledge of the differential expression of CD45RA and CD45RO can ameliorate our classificative approach to haematological malignancies, as well as disclose new multiple overlap points between normal and leukaemic cell differentiation.     

肝硬化患者外周血CD19+ CD25+细胞表达的临床意义

探讨肝硬化患者外周血CD19＋ CD25＋双阳性细胞表达的临床意义.采用流式细胞仪检测70例肝硬化患者和20例健康对照者外周血CD19＋ CD25＋细胞、T淋巴细胞以及B淋巴细胞的表达,免疫比浊法检测血清免疫球蛋白（IgG、IgM、IgA）水平.肝硬化患者外周血CD＋3、CD＋3 CD＋8细胞表达率和CD＋3、CD＋3 CD4＋、CD＋3 CD＋8细胞绝对数明显低于对照组（P均＜0.01）;而CD＋3 CD4＋/CD＋3 CD＋8比值、CD19＋、CD19＋ CD25＋细胞表达率以及免疫球蛋白（IgG、IgM、IgA）水平显著增高（P均0.05）.肝硬化患者CD19＋ CD25＋细胞表达率与ALT、IgG、IgA呈正相关（r为0.548、0.541、0.334,P均＜0.05）.食管胃底静脉曲张组CD＋3、CD＋3 CD4＋细胞绝对数以及CD＋3 CD＋8细胞表达率和绝对数明显低于未曲张组（P均＜0.01）;而CD＋3 CD4＋细胞表达率、CD＋3 CD4＋/CD＋3 CD＋8比值、免疫球蛋白（IgM、IgA）水平高于未曲张组（P均＜0.01）.肝硬化患者Child-Pugh分级越差,CD19＋ CD25＋细胞表达率和IgG、IgM、IgA水平明显升高（P均＜0.01）,而CD＋3、CD＋3 CD4＋、CD＋3 CD＋8细胞绝对数明显降低（P均＜0.05）.检测肝硬化患者外周血CD19＋ CD25＋细胞表达水平能反映患者的肝脏损伤程度和体液免疫状况,有助于指导临床治疗和预后判断.     

CD45RA expression by CD4 T lymphocytes in tumors invaded by B-cell non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD).

Little is known about the role of tumor infiltrating T lymphocytes (TIL-T) in the pathogenesis of malignant diseases and collaboration between normal and malignant cells has not yet been proved. In the present work, we have investigated whether immune T lymphocytes exist in tumors invaded by B-cell non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD). Therefore, we have studied the reactivity of the CD45RA monoclonal antibody, which discriminates between naive and memory CD4 T lymphocytes. Our results showed far lower percentages of CD4+ CD45RA+ in malignant lymphoma (30.3 +/- 15.0% in B-cell NHL, and 37.4 +/- 18.6% in HD) than in reactive hyperplasia (54.7 +/- 13.2%), leading to the conclusion of an accumulation of immune cells in tumor microenvironment. A further heterogeneity in the relative proportion of naive and memory TIL-T was also observed within lymphoma (range: 11 to 68% in B-cell NHL, 5 to 69% in HD). In B-cell NHL, it was related to histological features, as documented by the Kiel classification (P = .028), and to a stronger extent to cytological characteristics analysed with the Grenoble classification (P less than .0001): class 1 NHL, which are essentially indolent NHL displayed lower naive cells (22.2 +/- 7.4%) than class 3 NHL, which are more aggressive (40.1 +/- 16.1%). Among the monoclonal antibodies (mAb) defining the B-cell clone phenotype or activation state (CD19, CD20, CD21, CD22, CD23, CD24, CD5, CD10, CD11a, and Ki67), only CD23 (P = .0003) and Ki67 (P = .0007) revealed statistical association with the percentage of naive CD4 lymphocytes. No correlation could be demonstrated with the proportion of whole TIL-T, activated CD3 DR TIL-T, or CD4 subset.     

Cell surface expression of CD25, CD54, and CD95 on B- and T-cells in chronic lymphocytic leukaemia in relation to trisomy 12, atypical morphology and clinical course

BACKGROUND: Surface antigen expression can be used to define subgroups of patients with different clinical courses in chronic lymphocytic leukaemia of the B-cell type (CLL). PURPOSE-METHODS: To study the clinical significance of functional markers linked to proliferation (CD25), adhesion (CD54), and apoptosis (CD95) on B- and T-cells in 68 patients with CLL using dual colour flow cytometry (FCM). RESULTS: The mean proportion of CD19+ B-cells expressing CD25 was significantly higher in CLL patients compared to controls (P=0.02), while CD54+ and CD95+ B-cells did not differ significantly. In CLL with atypical morphology and in patients with trisomy 12, the mean percentage of CD25+ B-cells was lower than in typical CLL (P<0.02) and in patients with disomic tumor cells (P<0.03). Patients with 30% of CD25+ B-cells had a shorter median time to treatment than CD25-negative cases (P=0.01). A low CD54 expression was associated with a prolonged median time to treatment (P=0.004), low WBC counts (P<0.05), and low S-LDH (P=0.03). A high CD95 expression was correlated with elevated S-LDH (P=0.02) and a finding of lymphadenopathy (P=0.02). In individual patients there was a strong correlation between B- and T-cell expression of CD25 (P<0.0001), CD54 (P=0.0002), and CD95 (P=0.0002), respectively. CONCLUSIONS: CD25 and CD54 expression on CD19+ cells seems to give prognostic information. The strong correlation between the expression of CD25, CD54 and CD95 on B-and T-cells suggests that the expression of these antigens is not an inherent characteristic of the malignant B-cell clone.     

A rapid translocation of CD45RO but not CD45RA to lipid rafts in IL-6-induced proliferation in myeloma

CD45, a receptor-type tyrosine phosphatase, is required for interleukin-6 (IL-6)-induced proliferation in human myeloma cells, which express the shortest isoform, CD45RO, but not the longest isoform, CD45RA. Here, we showed that IL-6 induced the translocation of CD45 to lipid rafts in an isoform-dependent manner. In myeloma cells, CD45RO was translocated to lipid rafts more rapidly than CD45RB, but exogenously expressed CD45RA was not translocated. When an IL-6Ralpha-transfected B-cell line was stimulated with IL-6, CD45RA was not translocated, although CD45RB was. We further confirmed that the translocated CD45 bound to IL-6Ralpha, Lyn, and flotillin-2, and this was followed by the dephosphorylation of the negative regulatory Tyr507 of Lyn. CD45 also bound to phosphoprotein associated with glycosphingolipid-enriched microdomains (PAGs), which were subsequently dephosphorylated, resulting in the release of C-terminal src kinase (Csk) from lipid rafts. Therefore, these results indicate that a rapid translocation of CD45RO to lipid rafts may be responsible for IL-6-induced proliferation, and that the change from CD45RA to CD45RO confers the ability to respond to IL-6 in human myeloma cells.     

CD4+CD45RA+ cells (suppressor-inducer T cells) in thyroid tissue from patients with Graves' disease.

Previously, we used dual immunofluorescent analysis and showed that the thyroid gland from patients with Graves' disease had a reduced number of CD4+CD45RA+ cells, but an increased number of complementary CD4+CDw29+ cells. An immunohistochemical study, however, produced opposite results; interstitial lymphocytes predominantly expressed the CD45RA+ rather than the CDw29+ phenotype. Because the difference in findings may be due to differences in the techniques used, we did the following experiments: Mononuclear cells were treated with various amounts of collagenase (50-1000 mg/l) which had no effect on the cell surface antigens CD3, CD4 and CD45RA. A dual immunofluorescent study showed that the numbers of CD4+CD45RA+ and CD8+CD45RA+ cell population among CD45RA+ cell population were markedly decreased in the thyroid tissue, and that the CD45RA antigen on the intrathyroidal mononuclear cells was mainly expressed on the CD20+ cells. As the thyroid section had been fixed with acetone before immunohistochemical staining, CD45RA- cells were treated with acetone and stained with anti-CD45RA monoclonal antibody using an avidin-biotin peroxidase complex method. The results of this experiment suggest that there are cell surface molecules which react with anti-CD45RA monoclonal antibody after treatment with acetone in CD45RA- cells. The above findings confirm our previous results which showed that the thyroid glands of patients with Graves' disease have decreased numbers of suppressor-inducer T cells. Also, several problems exist in the detection of CD45RA+ cells when using an immunohistochemical method.     

Increased production of soluble CD23 in rheumatoid arthritis,and its regulation by interleukin-4

Objective. To assess CD23 status in rheumatoid arthritis (RA) patients, as defined by the levels of CD23 expression on peripheral blood mononuclear cells (PBMC), the levels of soluble CD23 (sCD23) in sera, and the production of sCD23 by PBMC cultures and its regulation by interleukin-4 (IL-4). Methods. CD23 expression as determined by double fluorescence-activated cell sorter analysis and sCD23 production as determined by immunoradiometric assay were investigated in 24 RA patients and 21 controls. Soluble CD23 was measured in sera and supernatants of PBMC, activated with polyclonal activators (pokeweed mitogen [PWM] or Staphylococcus aureus Cowan strain 1, [SAC]) used either alone or in combination with IL-2 or IL-4. Results. The percentage of B cells expressing CD23 and serum levels of sCD23 were increased in patients with RA. IL-4 was a potent inducer of sCD23 production in supernatants, whereas IL-2 was inactive. Costimulation with SAC or PWM did not increase the effect obtained with IL-4 alone. When sCD23 levels in RA and control supernatants were compared, spontaneous production was found to be increased in RA PBMC. This difference from control values was even more pronounced when sCD23 levels in PBMC and purified B cells in response to IL-4, either alone or in combination with SAC or PWM, were tested. In the same supernatants, the increased secretion of sCD23 induced by IL-4 was associated with an inhibitory effect of IL-4 on Ig production, a phenomenon that was more pronounced in RA PBMC than in controls. Conclusion. CD23 status in RA is characterized by increased expression of CD23 on B cells, increased production of sCD23 in sera and supernatants, and increased sensitivity of RA PBMC and B cells to IL-4.     

Modulation of T-Cell Adhesion Markers, and the CD45R and CD57 Antigens in Human Alcoholics

Direct and indirect evidence indicates that T cells are altered in alcoholics. The most commonly reported changes under direct examination have been consistent with an increased level of activation as reflected by shifts in the ratio of common leukocyte antigen isoforms expressed at the cell surface, by increases in the expression of class II antigen, or by alterations in the expression of various adhesion molecules. Functional evidence for T-cell abnormality includes loss of delayed hypersensitivity and a number of findings attributed to dysregulation of B cells by alcoholic T cells; these include the widely reported disturbances of immunoglobulin production in vivo and a range of abnormal responses when T and B cells are combined in vitro. Detailed flow cytometric examination of T cells from alcoholics with or without active liver disease reveals a significant loss of l -selectin CD8⁺ T cells, but not usually of CD4⁺ T cells. There is an inverse increase in the expression of CD11b on the CD8⁺ cells that have decreased L-selectin⁺ percentages. Both CD8⁺ and CD4⁺ T cells in alcoholics display a significant loss of the CD45RA isoform and a gain of cells exhibiting the CD45RO isoform. Other surface alterations include increased expression of CD57, a marker most commonly associated on T cells with conditions of chronic increased antigenic exposure. It is argued that these and other T-cell alterations in alcoholics are cytokine-driven in part and result in T-cell differentiation states that are functionally inappropriate. The results of these alterations may include reductions in normal lymphocyte traffic, an increase in cell-mediated cytotoxicity, and intermittent loss of normal suppressor functions for immunoglobulin production permitting increased autoantibody formation. Chronic excessive antigen exposure may contribute at other times to the development of abnormal regulatory suppression of the immune response.     

Relationship between CD45 antigen expression and putative stages of differentiation in B-cell malignancies.

The cell-surface antigen CD45 is a complex family of high-molecular-weight glycoproteins expressed on all lymphohematopoietic cells, but not in the same molecular isoform. This antigen complex is known to exhibit protein tyrosine phosphatase (PTPase) activity and appears to have a role in regulation of cell differentiation. In that CD45 expression parallels stages of differentiation in normal bone marrow B cells, it was of interest to evaluate this process in malignant B cells. Monoclonal antibodies (MoAbs) were used to investigate the quantitative expression of CD45 and CD45RA on the B cells of lymphoid leukemias. Employing standardized flow cytometric methods, it was found that the fluorescence intensity (FI) of immunostained malignant B cells, as a reflection of the antigen content, demonstrated correlations with the putative stage of cell differentiation for malignancies at the earlier stages, but at the later stages, a progressive loss of CD45 was observed. Since this antigen family has been found to display PTPase activity, further investigation of CD45 alterations in malignancies may provide insight into potential regulatory disturbances.