Immunohistochemical observations on cellular response in unilocular hydatid lesions and lymph nodes of cattle

As we believe the immunohistochemistry of the hydatid lesions and draining lymph nodes has never been studied, we collected them from the liver and lungs of cattle in Uruguay for such a study. Frozen sections of the tissues were immunohistochemically stained using monoclonal antibodies against surface markers CD2, CD4, CD5, CD8, B cell and granulocyte-monocyte/macrophage and antiserum against specific granules of bovine eosinophils. The adventitial layer of the cyst wall consists of a layer of epithelioid cells and connective tissue. The cells from the epithelioid cell layer were a kind of macrophage. In most cases having progressive hydatid cysts, CD8+ cells were predominant in the pericystic adventitia, and a relatively small number of CD4+ cells were in the same area. In the adventitial layer surrounding the regressive and involutional hydatid cysts, infiltrating lymphocytes were composed mostly of CD4+ cells. An eosinophil-mediated destruction of the laminated layer was recognized in the regressive and involuted hydatid cysts. The subpopulations of T cells in the local lymph nodes tended to be similar to T cells in the adventitial layer of hydatid lesions. From our findings, we consider that infiltration of eosinophils and the subpopulations of lymphocytes infiltrating the hydatid lesions in the liver and lungs are derived from cells in the draining lymph nodes of both organs.     

Long‐term amelioration of established collagen‐induced arthritis achieved with short‐term therapy combining anti‐CD3 and anti–tumor necrosis factor treatments

Objective

The goal of rheumatoid arthritis (RA) treatment is to achieve clinical remission in order to limit structural damage and physical disability. To this end, recent emphasis has been placed on aggressive treatment early in the course of disease with drugs such as anti–tumor necrosis factor (anti‐TNF) agents. As T cells are also thought to play an important role in the initiation of RA, we hypothesized that targeting both TNF and T cells would result in better outcomes. The aim of this study was to examine the efficacy of combined therapy with anti‐CD3 and anti‐TNF in experimental RA.

Methods

Two anti‐mouse antibodies were developed as surrogate reagents for anti‐TNF and anti‐CD3 therapies. Collagen‐induced arthritis (CIA) was induced in DBA/1 mice, and antibodies were injected intraperitoneally, either alone on in combination, at predetermined subtherapeutic doses. The frequency and number of pathogenic and regulatory CD4+ T cell subsets in the draining lymph nodes were determined in order to investigate the mechanisms of action.

Results

Strikingly, the combination of the two antibodies demonstrated a potent synergy in established CIA, with long‐term inhibition of disease progression and protection from joint destruction. The results did not demonstrate any enhancement of CD25+FoxP3+ regulatory T cells, but a profound depletion of pathogenic T cells from the draining lymph nodes was associated with reduced numbers of T cells in the joints.

Conclusion

A short course of combination therapy with anti‐CD3 and anti‐TNF efficiently depletes pathogenic T cells from the draining lymph nodes, reducing the numbers of T cells in the joints and affording long‐lasting inhibition of established CIA.

     

Cysticercosis: cellular immune responses during primary and secondary infection

Immune reactions to cysticercosis have been extensively studied in mice. The lack of significant lymphocyte infiltration into the livers of infected mice and the obvious role of antibodies in rejection has led to the general conclusion that cellular reactions do not play a role in protection against this disease. In contrast, the present study examining the immune response to cestode infections in a large animal model (sheep) revealed the presence of a massive and highly organized cellular infiltration in the livers after a secondary Taenia hydatigena infection. The majority of the infiltrating lymphocytes were of the CD4+ phenotype with much fewer CD8+ cells present. While most gamma delta-TCR+ cells in peripheral blood are SBU-T19+, the majority of gamma delta-TCR+ lymphocytes in the liver lesions are SBU-T19- suggesting selective migration of these cells into the lesions. In contrast to the diffuse distribution of T cells in the lesions, B cells were present as distinct aggregates. In primary T. hydatigena infections, host class I and class II MHC antigens were shown, for the first time in cestode infections, to be absorbed onto the surface of the metacestode bladderwall indicating their possible involvement in parasite survival. No immune reactions were observed close to the parasite although lymphocytes and eosinophils were infiltrating the adjacent portal tract areas. Most lymphocytes in both primary and secondary infections were positive for MHC class II antigens suggesting selective recruitment of activated cells to the site of infection. Significant changes in relative and absolute numbers of lymphocyte subpopulations were also observed in the draining hepatic lymph nodes dominated by a massive increase of B cells. In contrast, at the peak of local cellular infiltration, no changes in lymphocyte subpopulations were observed in peripheral blood showing the limited usefulness of this compartment in studying cellular changes in localized infections. The vigorous cellular response observed in the livers of sheep contrasts sharply with the lack of lymphocyte infiltration reported in mice indicating that small animal models may not be appropriate to study cellular responses to cysticercosis in large animals and man.     

Cells in lymph draining normal human skin-monoclonal antibody analysis

The immune cells which migrate into the human skin from the blood and subsequently leave it via lymph vessels play an important role in immune processes. We made use of the monoclonal antibodies, characterizing cell populations which migrate into the normal skin and which having traversed the tissue, could be recovered from the afferent lymph vessels. The percentage of OKM1+ cells (monocytes/macrophages, null cells) in lymph was low (8.9 +/- 1.6%) when compared to that of blood (16.5 +/- 4.6%) (p less than 0.05). The OKM1 antibody labeled only 40% of the large macrophage-like lymph cells. The percentage of OKT3+ (T cells) in lymph was higher (75.4 +/- 4.0%) than in blood (54.0 +/- 4.5%) (p less than 0.05) as was that of the OKT4+ (inducer/helper) subset (41.5 +/- 9.5 and 33.3 +/- 4.8%, p less than 0.05), while cells of the OKT8+ (suppressor/cytotoxic) subset were found to be less numerous in lymph than in blood. (18.4 +/- 6.2% and 20.3 +/- 4.9%, p less than 0.05). The OKI a1+ cell population consisted of large veiled macrophage-like cells and only very few small cells. Around 60% of the large mononuclear cells present in lymph reacted with OKT6 antibody specific for cortical thymocytes. The finding of high proportions of T cells, cells bearing la-like antigens, and a high inducer/suppressor ratio in normal prenodal lymph reflects the intensity of "physiological" immune processes in the normal skin.     

Induction of CD4+CD8+ double positive T cells and increase in CD5+ B cells in efferent lymph in sheep infected with Trypanosoma evansi

The effects of Trypanosoma evansi on efferent lymphocyte phenotypes draining from a lymph node primed with Pasteurella haemolytica vaccine were studied in sheep. The prefemoral efferent lymphatic ducts of the infected sheep along with those of two uninfected sheep were surgically cannulated. Lymph was collected and lymphocytes recovered from it analysed by two-colour indirect immunofluorescence staining and cytofluoremetry in a fluorescence activated cell analyser (FACSCAN). The study showed the appearance and persistence of T. evansi in the efferent lymph for a long period of time and the appearance of CD4⁺CD8⁺ (double positive, DP) T lymphocytes in the efferent lymph of infected animals. The infection also resulted in increases in CD5⁺ B cells in the prefemoral efferent lymph. In addition, there were decreases in the output of conventional B cells, CD5⁺ and CD4⁺ T cell subsets but large increases in CD8⁺ cells followed by terminal depletion of all cell subsets. In contrast, inoculation of sheep with pasteurella vaccine antigen alone produced little alterations in the proportions, but large increases in the numbers of all T cell subsets except that of CD8⁺ cells which also showed little variation; and there was a concurrent increase in the numbers and proportions of efferent B cells. In addition, the abnormal expression of DP and CD5⁺ B cells did not occur in the uninfected vaccinated sheep. It is concluded that these abnormal changes in the kinetics of efferent lymphocyte phenotypes are likely to play a role in the genesis of the generalized immunosuppression seen in trypanosome-infected hosts.     

Role of gamma interferon and T cells in congenital Toxoplasma transmission

In the BALB/c mouse model, primary infection with Toxoplasma gondii during the second third of gestation leads to a high percentage of infected foetuses. However, immunity induced by infection contracted before pregnancy prevents parasites from crossing the placenta and completely protects the foetuses, as well as the pregnant women. In order to clarify the roles of CD4+, CD8+ T lymphocytes and IFN-gamma in this protection, pregnant BALB/c mice were treated with depleting monoclonal antibodies against CD4, CD8, IFN-gamma, or control antibody. Only the foetuses of the groups treated with anti-CD8 and anti-IFN-gamma antibodies developed congenital toxoplasmosis. The maternal production of IFN-gamma was depressed in the mice depleted of CD4 and CD8 cells (P < 0.001). Determination of the blood parasite load demonstrated that materno-foetal transmission of T. gondii correlates with maternal parasitaemia. Together, these results show that CD8+ T lymphocytes and IFN-gamma play an important role in protection against congenital toxoplasmosis during reinfection.     

Lymphocyte phenotypes in the abomasal mucosa of sheep infected with Haemonchus contortus

Lymphocyte subpopulations in the abomasal mucosa of worm-free and parasitized sheep were assessed in situ. A preponderance of T-lymphocytes, with approximately equal numbers of cells expressing CD5, CD4 and CD8 antigens, was found. Most of the lymphocytes expressing CD8 lacked CD5. Using a panel of 15 monoclonal antibodies to ovine leucocyte antigens, abomasal lymphoid follicles in the mucosa were shown to resemble lymph node follicles phenotypically. Abomasal epithelial cells contained major histocompatibility complex (MHC) class II antigen. Infection or hyperimmunization of pasture-reared sheep with the gastric nematode Haemonchus contortus increased the numbers of mucosal mast cells and eosinophils but did not alter the phenotypic composition or number of mucosal lymphocytes or the pattern of expression of MHC class II antigens.     

CD8+ T Lymphocyte Subsets in Bladder Tumor Draining Lymph Nodes

Background: Cytotoxic CD8+ T cells, as essential parts of the adaptive immune system, play pivotal roles in anti-tumor immune responses. It is well documented that cytokine expression profiles and activation status of these cells during anti-tumor immune responses affect the outcome of host-tumor interaction. Objective: To investigate the percentages of CD8+ lymphocytes and their subsets in tumor draining lymph nodes of patients with bladder cancer. Methods: Forty-five patients with bladder cancer, candidate for radical cystectomy, were recruited. Mononuclear cells were isolated from draining lymph nodes using Ficoll-Hypaque gradient centrifugation, and were activated by PMA/Ionomycin in the presence of Golgi inhibitors. The cells were then permeabilized and stained with appropriate flourochrome conjugated antibodies against CD3, CD8, IFN-γ, IL-17 and IL-4 molecules. Data were collected on a fourcolor flow cytometer and analyzed by CellQuestPro software. Results: Despite no difference in the frequency of IL-17 producing CD8+ (Tc17) lymphocytes, the mean expression of IL-17 in this subset was significantly elevated in high-grade patients (p=0.011). The percentage of double positive IFN-γ/IL-17 CD8+ lymphocytes was also significantly increased in node positive patients compared to node negative ones (p=0.046). Our results also demonstrated that the percentage of IFN-γ producing CD8+ (Tc1) lymphocytes was significantly increased in the patients with higher histological grade compared to those with lower ones (p=0.038). Conclusion: IFN-γ and IL-17 producing CD8+ T cells may increase in advanced stages of bladder cancer, but their correlation with tumor prognosis remains to be investigated.     

Lymphocyte subpopulations of sheep in protective immunity to Taenia hydatigena

Lymphocyte subpopulations entering the liver and surrounding the rejection sites during a 9-day period after infection of immune sheep with Taenia hydatigena were identified with the aid of monoclonal antibodies against lymphocyte cell surface markers. Viable lymphocytes were isolated from the liver tissue and stained by indirect immunofluorescence for subsequent flow cytometry analysis. Over the first 6 days after challenge infection a marked increase in the ratio of T-helper to T-suppressor/cytotoxic lymphocytes was observed. SBU-T19+ lymphocytes, a CD5+ T-cell subpopulation uniquely identified in the sheep, were present in small numbers in sheep liver both before and after infection. There was a large, continuous increase of sIg+ B-cells over the 9-day observation period after infection. Eosinophils were the predominant granulocytes in the liver of infected sheep. The exact location of the leucocyte subpopulations in respect to the rejection sites in infected liver was determined by in-situ immunoperoxidase staining of frozen liver sections. The evolution of the parasite-induced leucocyte response was characterized by the appearance of a central core of eosinophils surrounded by increasing numbers of CD4+ helper T-cells. CD8+ (suppressor/cytotoxic) and SBU-T19+ T-lymphocytes were present in much smaller numbers and by day 9 after infection were located predominantly around the periphery of the lesions. Distinct foci of tightly packed B-cells developed within the lesions and increased dramatically in size over the 9-day observation period. At this time, lesions appeared as compact aggregations of leucocytes encircled by a second band of eosinophils. Both T- and B-lymphocytes within the lesions stained positive for class II major histocompatibility antigens.     

Proliferative responses of human intraepithelial lymphocytes to various T-cell stimuli

Human intraepithelial lymphocytes (IEL) are CD8+ T cells located between intestinal epithelial cells, capable of only minimal proliferation to mitogens but brisk proliferation to mitogens combined with sheep red blood cells. This study examines this differential response of IEL. Both IEL and CD8+ T lymphocytes from the peripheral blood are predominantly CD2+, CD3+, CD4-, CD5+, CD8+, and express the alpha beta subunits of the T-cell receptor. Human IEL express the same densities of the CD2, CD3, and CD8 antigens but a lower density of the CD5 antigen than do peripheral blood CD8+ T cells. The proliferation of IEL is significantly less than that of peripheral blood CD8+ T lymphocytes in response to phytohemagglutinin, to concanavalin A, or to anti-CD3 antibody bound to Sepharose (p less than 0.05). Supplementing IEL with interleukin-1, interleukin-2, or autologous peripheral blood macrophages does not completely reconstitute the proliferative response of IEL to these stimuli. Rather, the low proliferation of IEL to these stimuli is due to incomplete activation, as demonstrated by the low percentage of CD25 (Tac)+ lymphocytes with concanavalin A or the low density of the CD25 antigen with phytohemagglutinin. Both IEL and peripheral blood CD8+ T lymphocytes proliferate minimally in response to alloantigens or to interleukin-2, but briskly in response to stimuli of the CD2 receptor such as the combination of anti-T11(2) and anti-T11(3) antibodies or mitogen and sheep red blood cells. The sheep red blood cells enhance the mitogen-induced response of IEL by augmenting events of activation, both interleukin-2 production and interleukin-2 receptor expression. Thus, IEL represent an unusual compartment of CD2+, CD3+ T lymphocytes that are activated more completely by stimuli of the CD2 receptor than by stimuli of the CD3 receptor or by T-cell mitogens.     

The in vitro effect of interferon-alpha 2a on CD95 expression of T cells in hepatitis B

BACKGROUND/AIMS: In chronic hepatitis B, apoptotic rate of peripheral cytotoxic T cells may be related with hepatocyte injury. We aimed to investigate Fas (CD95) expression of peripheral cytotoxic T cells and to show the in vitro effect of interferon-alpha 2a on Fas expression and apoptosis. METHODOLOGY: The study group consisted of 17 patients with chronic hepatitis B and control group consisted of 10 healthy subjects. Apoptotic cells were identified by flow-cytometric assay using Annexin V and propidium iodide. We used monoclonal antibodies stained by direct immunofluorescent method to show surface molecules. CH-11 monoclonal antibodies were used as anti-Fas antibodies. RESULTS: Basal expressions of CD95 and CD8+ CD95+ in the peripheral mononuclear cells were higher in chronic hepatitis B patients than controls. In vitro treatment with interferon-alpha 2a increased the percentage of CD8+ 95+ peripheral mononuclear blood cells in controls; this effect was less remarkable in patients with chronic B hepatitis, and the difference was not statistically significant. The number of apoptotic cytotoxic T cells also increased in 5 subjects of the study group and 3 subjects of controls; the percentage of CD95+ cells increased in 7 of 17 patients and 8 of 10 controls. The percentage of CD8+ 95+ cells and the apoptotic rate of CD8+ cells were not different between study group and controls after combined treatment with interferon-alpha 2a and monoclonal stimulating anti-Fas antibodies. CONCLUSIONS: We suggest that interferon-alpha 2a does not induce Fas-dependent apoptosis in CD8+ peripheral T cells of the patients with chronic hepatitis B, and CD95 molecules on peripheral cytotoxic T cells might be defective.     

Immunological and molecular biological identification of a true case of T-hairy cell leukaemia

A hairy cell leukaemia (HCL) patient is presented in whom the peripheral blood mononuclear cells (PBMCs) carried suppressor T-cell markers (CD3+, CD2+, CD8+/CD4-, CD38+). Analysis of genomic DNA of PBMNC showed the presence of a monoclonal population of T cells, the T-cell receptor (TCR) beta-chain gene being rearranged on both alleles (DR/DR), while the immunoglobulin (Ig) heavy chain-genes were in germline configuration. The neoplastic cells were found to react with the monoclonal antibody RAB-1 - originally described as belonging to the B lineage-restricted monoclonal antibodies - and to carry RAB-1/CD-8 in a double marker assay. Natural killer activity of PBMNCs against K562 target cells was severely reduced, while the cells were found to exert strong antibody-dependent cellular cytotoxicity.     

FIV infection induces unique changes in phenotype and cellularity in the medial iliac lymph node and intestinal IEL

Studies of human immunodeficiency virus-1 (HIV-1)-infected patients and simian immunodeficiency virus (SIV)-infected macaques have identified profound depletion of CD4(+) T cells and expansion of CD8(+) T cells in the gastrointestinal lamina propria. Less attention has been given to CD8(+) intraepithelial lymphocytes (IEL), and no studies have concurrently examined inductive sites such as draining lymph nodes. Our preliminary data in the feline immunodeficiency virus (FIV) animal model suggested additional changes in IEL, and marked differences in the responses of lymph nodes draining different mucosal sites. To address this, we quantified the absolute leukocyte yield and examined the phenotype of cells from small intestinal IEL, mesenteric lymph node (MLN), and medial iliac lymph node (ILN) from chronically FIV-infected cats. The cellularity of the ILN was increased 530% in FIV-infected animals with an expansion of CD62L(+) cells, suggesting an increased population of naive T cells. The number of CD4(+), as well as CD8(+), T cells was increased in the ILN, resulting in a CD4:CD8 ratio greater than 1:1. In contrast, reduced cellularity, specific loss of CD4(+) T cells, and inversion of the CD4:CD8 ratio was observed in the MLN, which drains the intestine. In IEL, loss of CD8alpha, CD8beta, and CD4-expressing T cells was found in FIV-infected cats. Furthermore, expression intensity of CD8alpha and CD5, markers known to be important in T cell function, was markedly decreased on IEL. These findings expand the array of immune alterations induced by lentiviral infection and indicate that characterization of multiple mucosal sites will be necessary to fully understand the pathogenesis of HIV-1 infection.     

CD8+ T-cell-mediated killing of donor dendritic cells prevents alloreactive T helper type-2 responses in vivo

Accumulating evidence indicates that, in absence of CD8+ T-cell activation, CD4+ T-cell-mediated allograft rejection is associated with a dominant Th2-cell response and eosinophil infiltrates. In this study, we analyzed the mechanisms by which CD8+ T cells regulate alloreactive CD4+ T-cell priming and differentiation into interleukin 4 (IL-4)-producing cells. We showed that interferon gamma (IFN-gamma) production by CD8+ T cells was dispensable for the inhibition of Th2-cell development, as well as tissue eosinophilia and type 2 cytokine production in the rejected grafts. Since we noticed that CD8+ T cells not only suppressed Th2 differentiation, but also down-modulated the overall priming of alloreactive CD4+ T cells, we evaluated whether CD8+ T cells act by limiting the accumulation of donor-derived dendritic cells (DCs) in lymph nodes. We found that indeed, alloreactive CD8+ T cells rapidly eliminated allogeneic DCs from T-cell areas of draining lymph nodes, through a perforin-dependent mechanism. Thus, our data demonstrate that cytotoxic T lymphocyte (CTL)-mediated clearance of allogeneic DCs is a negative feedback mechanism that limits the duration of alloantigen presentation in draining lymph nodes, thereby modulating the amplitude and polarization of the primary alloreactive CD4+ T-cell responses.     

Induction of CD4+ and CD8+ T cell responses in efferent lymph responding to Toxoplasma gondii infection: analysis of phenotype and function

The kinetics of induction of T cell responses were examined in efferent lymph from a node draining the site of a primary inoculation of Toxoplasma gondii. The numbers of T cells increased after infection, due initially to an expansion of the CD4⁺ T cell population followed by an increase in the number of CD8⁺ T cells which coincided with the peak lymphoblast response. Proliferative responses of CD4⁺ T cells to T. gondii antigen were detectable from day six after infection and immune efferent lymph cells inhibited the intracellular multiplication of T. gondii in vitro. Optimum inhibition was achieved using CD8⁺ T cells restimulated in vitro, and the effector function appeared to be directed preferentially against the autologous rather than the allogeneic infected target cell. The results provide unique information on the induction of immune responses to T. gondii in vivo and provide evidence that both CD4⁺ and CD8⁺ T cells are necessary for the development of protective immunity induced by the S48 strain of T. gondii which is used as a live vaccine in sheep.     

Correlation of 4-1BBL+ B Cells in Tumor Draining Lymph Nodes with Pathological Characteristics of Breast Cancer

Background: B cells can increase the expression of granzyme B in CD8+ T cells through 4-1BBL/4-1BB interaction and promote anti-tumor immunity. Objective: To investigate the expression of 4-1BBL on B cells in the breast tumor draining lymph nodes (TDLNs) and its association with disease parameters. Methods: Using Ficoll-Hypaque gradient centrifugation, mononuclear cells were isolated from axillary lymph nodes of 42 patients. Cells received 4 hours of PMA/Ionomycin stimulation, in vitro. Both unstimulated and stimulated cells were stained with anti‒CD19 and anti‒4-1BBL antibodies and subjected to flow cytometry. Results: 4-1BBL expression was detected on 2.8 ± 1.7% of unstimulated B cells, while 27.4 ± 11.9% of B cells expressed this co-stimulatory molecule following stimulation. In steady state, the percentage of 4-1BBL+ B cells was not associated with cancer characteristics. However, in patients with invasive ductal carcinoma, the percentage of 4-1BBL expressing B cells in stimulated condition had a decreasing trend in grade III, compared to grade II+I. In addition, significantly higher frequency of 4-1BBL+ B cells was seen in the TDLNs of ER+ or PR+ compared with ER‒ or PR‒ patients (p=0.021 and p=0.015, respectively). No significant associations were observed between the frequency of 4-1BBL+ B cells and the number of involved LNs, Her2 expression or disease stage. Conclusions: The frequency of 4-1BBL+ B cells significantly increased following a short time activation, and showed relative and significant associations with tumor grade and estrogen receptor status, respectively. More investigations are required to evaluate the potential of 4-1BBL+ B cells for use in immunotherapy.     

Effect of chemotherapy on T-lymphocyte subsets in B-cell proliferative disorders

Summary The T-cell subset distribution and the activity markers of 41 patients with multiple Myeloma, Waldenström's macroglobulinaemia and benign monoclonal gammopathy were repeatedly analysed using monoclonal antibodies (T3, T4, T8, anti-TAC, anti DR) and rosetting techniques. In myeloma and macroglobulinaemia the relative and absolute numbers of T4⁺ cells were diminished while the absolute number of T8⁺ cells was not decreased. No significant difference between stage I and III of the myeloma disease was seen. The diminished number of T4⁺ cells in myeloma was partly due to the effect of chemotherapy. Chemotherapy-induced lymphopenia resulted in a drop of circulating T4⁺ cells and an inverted T4/T8 cell ratio. Untreated patients with myeloma were not significantly different from patients with benign gammopathy. Patients with macroglobulinaemia differed from patients with myeloma as they had an increased absolute T8 cell count and a significantly elevated percentage of TAC⁺ (= IL 2 receptor expressing) cells. In macroglobulinaemia chemotherapy affected also the T8⁺ cell subset. Thus, patients with macroglobulinaemia, but not with myeloma appear to have activated T8⁺ cells in their circulation.     

Pregnancy in patients with ankylosing spondylitis: Do regulatory T cells play a role?

Objective

To investigate the numerical and functional changes of CD4+CD25^high regulatory T (Treg) cells during pregnancy and postpartum in patients with ankylosing spondylitis (AS).

Methods

The frequency of CD4+CD25^high T cells was determined by flow cytometry in 10 pregnant and 5 nonpregnant patients with AS as well as in 14 pregnant and 4 nonpregnant healthy controls. Pregnant individuals were investigated at the third trimester and 8 weeks postpartum. Treg cells and CD4+CD25? effector T (Teff) cells separated by fluorescence‐activated cell sorting were stimulated with anti‐CD3 and anti‐CD28 monoclonal antibodies, alone or in coculture, to investigate proliferation and cytokine secretion.

Results

The frequency of CD4+CD25^high Treg cells was significantly higher during pregnancy than postpartum in both healthy control subjects and patients with AS. In contrast to Treg cells in healthy pregnant women, Treg cells in pregnant women with AS secreted only small amounts of interleukin‐10 and showed lower suppression of tumor necrosis factor α and interferon‐γ secretion by CD4+CD25? Teff cells. At the postpartum time point, proinflammatory cytokine levels in the Treg/Teff cell cocultures and Teff cell monocultures were significantly higher in patients with AS than in healthy controls.

Conclusion

Pregnancy influenced the expansion and cytokine secretion of Treg cells in both patients with AS and control subjects. However, the Treg cells of pregnant patients with AS failed to support an antiinflammatory cytokine milieu, thereby possibly contributing to the persistent disease activity of AS during pregnancy.

     

IgE responses in the serum and gastric lymph of sheep infected with Teladorsagia circumcincta

The IgE response of naive or previously infected sheep to 50 000 infective larvae of Teladorsagia circumcincta was monitored in serum and gastric lymph using a monoclonal antibody generated to recombinant ovine IgE in a dot blot assay. In 4/5 naive sheep, lymph and serum IgE concentrations increased from days 8 and 14 after infection, respectively. In most previously infected sheep, the IgE response to challenge was more rapid, although not necessarily greater than that following a primary infection. IgE concentrations in lymph were some 4-fold higher than in serum indicating that its source was the mucosa or draining nodes.     

Induction of costimulation of human CD4 T cells by tumor necrosis factor–related apoptosis‐inducing ligand: Possible role in T cell activation in systemic lupus erythematosus

Objective

Tumor necrosis factor–related apoptosis‐inducing ligand (TRAIL) has recently been shown to induce costimulation of mouse T cells in conjunction with signals from the T cell receptor. This study was undertaken to investigate TRAIL‐induced costimulation of human T cells in order to determine the role of TRAIL‐induced T cell activation in human systemic lupus erythematosus (SLE).

Methods

An in vitro T cell stimulation system with immobilized anti‐CD3 and recombinant TRAIL receptor DR4‐Fc proteins was used to activate human T cells purified from healthy individuals and from patients with SLE. The T cells were stimulated in vitro to assay their proliferation response by ³H‐thymidine incorporation, and their cytokine production by enzyme‐linked immunosorbent assay. Activation of p38 MAPK after TRAIL stimulation was detected with specific anti–phospho‐p38 MAPK monoclonal antibodies in Western blots.

Results

Enhanced T cell proliferation and increased interleukin‐2 and interferon‐γ (IFNγ) production were demonstrated in human T cells after stimulation with immobilized DR4‐Fc and anti‐CD3 in vitro. TRAIL engagement selectively activated human CD4, rather than CD8, T cells and augmented IFNγ production. Activation of p38 MAPK was detected after TRAIL‐induced T cell activation. T cells isolated from patients with SLE demonstrated a stronger response to TRAIL‐induced costimulation, in terms of proliferation and increased up‐regulation of CD25 after activation, when compared with T cells from healthy subjects.

Conclusion

TRAIL engagement induces costimulation of human CD4 T cells via a p38 MAPK–dependent pathway. The results suggest that enhanced reactivity of T cells to autoantigens as a result of TRAIL‐induced costimulation may play a role in the development of human autoimmune diseases.