Liver transplantation in an adolescent with acute liver failure from acute lymphoblastic leukemia.

The most common identifiable causes of acute liver failure in pediatric patients are infection, drug toxicity, metabolic disease, and autoimmune processes. In many cases, the etiology of acute liver failure cannot be determined. Acute leukemia is an extremely rare cause of acute liver failure, and liver transplantation has traditionally been contraindicated in this setting. We report a case of acute liver failure in a previously healthy 15-yr-old male from pre-B-cell acute lymphoblastic leukemia. He underwent liver transplantation before the diagnosis was established, and has subsequently received chemotherapy for pre-B-cell acute lymphoblastic leukemia. He is currently alive 31 months post-transplantation. The published literature describing acute lymphoblastic leukemia as a cause of acute liver failure is reviewed.

Suppression of renal disease and mortality in the female NZB x NZW F1 mouse model of systemic lupus erythematosus (SLE) by chenodeoxycholic acid.

The objective of this study was to examine the effects of ursodeoxycholic (UDCA) and chenodeoxycholic acid (CDCA) on autoimmune disease in the NZB x NZW F1 (B/W) mouse model of systemic lupus erythematosus (SLE). The development of murine lupus was assessed in female B/W mice given UDCA or CDCA. At 6 week intervals mice were examined for weight change, albuminuria, anti-DNA antibody and total IgG levels. Morbidity and mortality were assessed daily. UDCA- and CDCA-treated mice were examined at 24 weeks of age for serum cytokines, lymphocyte phenotype, and in vitro cytokine production after immunization with DNP-KLH. Liver and kidneys were examined histopathologically. The administration of UDCA and CDCA was tolerated without side effects. Weight gain in UDCA- or CDCA-treated and control mice was identical through 24 weeks of age. CDCA, but not UDCA, suppressed the development of renal disease. CDCA-treated B/W mice also had improved survival compared to UDCA-treated or control B/W mice. There were no significant effects of CDCA on anti-DNA antibodies, serum total IgG, or other immunologic parameters. CDCA-treated mice had lower serum IFN-gamma concentrations compared to control and UDCA-treated mice. The bile acid, CDCA, significantly inhibited the development of renal disease and modestly prolonged lifespan in the female B/W mouse model of SLE. Suppression of glomerulonephritis was associated with lower serum IFNgamma concentrations. Further investigation is needed to verify potential mechanisms of action, but these findings suggest that bile acids may alter the development or progression of autoimmunity.

Antioxidants suppress mortality in the female NZB x NZW F1 mouse model of systemic lupus erythematosus (SLE).

Inflammation produces reactive oxygen intermediates (ROI) that cause vascular damage and activate T lymphocytes. Conversely, antioxidants not only protect tissue from oxidative damage but also suppress immune reactivity. The objective of this study was to examine immunomodulatory effects of the non-enzymatic antioxidants, N-acetylcysteine (NAC) and cysteamine (CYST), on autoimmune disease, glomerulonephritis, and mortality in the female B/W mouse model of human systemic lupus erythematosus (SLE). The development of murine lupus was assessed during the lifespan of female B/W mice given NAC or CYST. Morbidity and mortality were assessed daily. At 6 week intervals mice were examined for weight change, albuminuria, serum BUN, antibodies to DNA, and IgG immunoglobulin levels. Serum prolactin, estrogen and progesterone were measured at 18 weeks of age. In a parallel study, NAC- and CYST-treated and control B/W mice were examined at 24 weeks of age for interval renal histopathology, lymphocyte adhesion molecule expression, and antibody titers and in vitro cytokine production in response to immunization with DNP-KLH. CYST significantly suppressed development of albuminuria and azotemia at 36 and 42 weeks of age compared to control and NAC-treated mice. NAC significantly suppressed anti-DNA antibody levels at 24 weeks. In contrast CYST significantly increased anti-DNA antibody levels at 18 weeks of age (P < 0.001 CYST vs control and NAC-treated mice). Kidneys of CYST-treated mice also had accelerated inflammatory histologic changes despite their lower incidence of albuminuria and azotemia. Mean (+/- s.e.m.) survival of control mice was 33 +/- 2 weeks compared to 38 +/- 2 weeks in NAC-treated mice (P < 0.05 vs control), and 48 +/- 2 weeks in the CYST-treated group (P < 0.01 vs control mice). The antioxidants, NAC and CYST, significantly improved mortality in the female B/W mouse model of SLE. NAC suppressed autoantibody formation and modestly prolonged survival. CYST, despite its augmentation of anti-DNA levels and renal inflammatory changes, inhibited the development of renal insufficiency and markedly improved survival. These findings suggest that ROIs play a role in the pathogenesis of lupus nephritis and that antioxidants reduce the damage causing renal insufficiency. Antioxidants may be a beneficial adjunctive therapy in the treatment of human SLE.

Value of CD23 determination by flow cytometry in differentiating mantle cell lymphoma from chronic lymphocytic leukemia/small lymphocytic lymphoma.

Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) share many morphologic and immunophenotypic features. In addition to histomorphologic examination, it is customary to use the absence of CD23 to differentiate MCL from CLL/SLL, based primarily on reported comparisons of immunohistochemical staining of tissue sections. These findings are widely extrapolated to flow cytometric analysis, although available data are contradictory and not sufficiently detailed. We compared expression of CD23 by flow cytometry in 22 cases of MCL and 25 cases of CLL/SLL. Lymphoma cells in 12 of 22 MCLs were negative for CD23, and 10 showed dim expression. In contrast, none of 25 CLL/SLLs were negative for CD23, 4 were dimly positive, and 21 were moderately or brightly positive. Thus, a significant proportion of MCL exhibited overlap of CD23 expression in the low-intensity range with CLL/SLL. Clinically, there was no correlation between the intensity of CD23 expression and clinical stage at diagnosis or survival. These findings emphasize that by flow cytometry, MCL can be differentiated reliably from CLL/SLL using CD23 if negative expression is observed. However, with dimly positive expression, interpretation should be cautious.

Progesterone inhibits glucocorticoid-induced murine thymocyte apoptosis.

Sex and sex hormones modulate immune development and responses. A primary target of their effects is the structure and cellularity of the thymus; therefore, we examined the effects of sex and sex steroids on thymocyte apoptosis. We demonstrate initially that male DBA mice have a significantly higher percentage of glucocorticoid-induced apoptotic thymocytes (46.1+/-3.8%) than their female counterparts (31.6+/-3.1%; P=0.012). We postulated that this gender difference was due to differential modulation of glucocorticoid-induced apoptosis by sex hormones such as estrogen, testosterone or progesterone. Both estrogen and testosterone increased in vitro thymocyte apoptosis. In contrast, progesterone not only inhibited spontaneous in vitro thymocyte apoptosis, but also prevented in vitro glucocorticoid-induced apoptosis. Progesterone administration also suppressed glucocorticoid-induced in vivo thymocyte apoptosis. These results suggest that anti-apoptotic effects of progesterone may influence T cell development and subsequent immune responses.

Increased glomerular deposits of von Willebrand factor in chronic, but not acute, rejection of primate renal allografts.

BACKGROUND: In our previously described primate renal allograft model, T cell ablation leads to long-term graft survival. The role of endothelial cell alteration in chronic rejection was examined in our model. METHODS: Renal transplants were performed in rhesus monkeys using a T cell- depleting immunotoxin, FN18-CRM9. Sections from 10 rejected kidneys (5 acute and 7 chronic rejection) were examined after immunohistochemical staining for expression of endothelium-related proteins [von Willebrand factor (vWF), CD62P, and CD31], fibrinogen, and a macrophage marker (CD68). Glomerular staining for each antigen was graded on a semiquantitative scale. RESULTS: Intense staining for vWF was consistently observed in glomerular endothelium, subendothelium, and mesangium in all kidneys removed due to chronic rejection. vWF staining was weak in kidneys showing acute rejection. The difference in glomerular staining was statistically significant. Staining for vWF in extraglomerular vessels was nearly identical in kidneys showing acute and chronic rejection. Expression of CD62P was increased in extraglomerular vessels in allografts with chronic rejection, but the glomeruli showed little or no staining. There was no significant difference in the glomerular staining for CD62P or CD31 in organs showing acute and chronic rejection. Fibrinogen staining of glomerular mesangium was seen in kidneys with chronic rejection. Macrophages (CD68+) infiltrating glomeruli were more numerous in kidneys showing chronic rejection. CONCLUSION: Increased glomerular deposition of vWF in renal allografts showing chronic rejection, without increased staining for CD62P or CD31, suggests increased constitutive secretion of vWF from endothelial cells as a component of the mechanism of chronic rejection in our model.

Mycophenolate mofetil suppresses autoimmunity and mortality in the female NZB x NZW F1 mouse model of systemic lupus erythematosus.

OBJECTIVE: To examine the effects of the immunosuppressant, mycophenolate mofetil (MM), on autoimmunity, glomerulonephritis, and mortality in the female NZB x NZW F1 (B/W) mouse model of systemic lupus erythematosus (SLE). METHODS: The development of murine lupus was assessed during the lifespan of 10 female B/W mice given 200 mg/kg/day of MM compared to 10 female B/W mice given vehicle. At 6 week intervals, mice were examined for weight change, albuminuria, antibodies to DNA, and IgG immunoglobulin levels. Morbidity and mortality were assessed daily. In a parallel study, MM treated and control B/W mice were examined at 18 weeks of age for splenocyte phenotype and adhesion molecule expression, as well as antibody titers and in vitro cytokine production in response to immunization with dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH). RESULTS: The administration of MM was well tolerated without apparent side effects. Weight gain in MM treated and control mice was identical through 36 weeks of age. In the treatment group, MM suppressed the development of albuminuria and anti-DNA antibodies compared to the control animals. There were no significant differences between groups in serum concentrations of total IgG. At 60 weeks of age survival in the MM treated group was 100% compared to 10% in the control group. MM did not alter the percentages of CD4, CD8, or IgM positive splenocytes; however, the percentage of CD4+ T lymphocytes expressing very late antigen 4 and intercellular adhesion molecule 1 was reduced. MM inhibited the antibody response to DNP-KLH immunization in vivo; however, in vitro cytokine production in response to KLH was not suppressed. CONCLUSION: MM suppressed the development of autoimmunity and prolonged lifespan in the female B/W mouse model of SLE. Suppression of autoimmunity was achieved without obvious side effects or altered CD4:CD8 T cell ratios. MM may be a useful primary or adjunctive therapy in human SLE.

Epitope-specific signaling through CD45 on T lymphocytes leads to cAMP synthesis in monocytes after ICAM-1-dependent cellular interaction.

We recently demonstrated that different CD45 monoclonal antibodies (mAb) are able to induce cellular aggregation in human peripheral blood mononuclear cells (PBMC) through LFA-1/ICAM-1 interactions. Such interactions could be down-modulated by protein kinase (PK) A/G inhibitors, but were unaffected by inhibitors of PKC, suggesting the involvement of PKA or PKG in CD45 mAb-induced adhesion. In this study we show that after incubation of PBMC with several (but not all) mAb to CD45, CD45RO and CD45RA, intracellular cAMP, but not cGMP concentrations readily increase, reaching a maximum 30 min after start of activation. As evidenced by several lines of investigation cAMP accumulation was independent of Fc receptor-associated signaling as well as tyrosine phosphatase activity of CD45. In highly pure T lymphocytes, CD45 mAb were unable to induce cAMP synthesis, but readily did so after addition of autologous monocytes. After paraformaldehyde fixation of both quiescent or IFN-gamma/TNF-alpha-preactivated monocytes, cAMP production was no longer detectable, suggesting monocytes as the cell of origin for the increased cAMP synthesis. Further, cAMP accumulation in monocytes occurred after reconstitution to T lymphocytes preincubated with CD45 mAb and extensively washed. Importantly, pretreatment of T lymphocyte/monocyte mixtures with LFA-1 mAb and/or ICAM-1 mAb down-regulated CD45 mAb-induced cAMP synthesis. Finally, we demonstrate that CD45 mAb are not only capable of inducing cAMP production, but also of directly stimulating PKA enzyme activity. Based on the data presented, we propose that CD45 signaling in T lymphocytes subsequently activates cAMP accumulation and PKA activation in monocytes via LFA-1/ICAM-1-dependent cellular interactions.

In vivo molecular analysis of cytokines in a murine model of ocular onchocerciasis. I. Up-regulation of IL-4 and IL-5 mRNAs and not IL-2 and IFN gamma mRNAs in the cornea due to experimental interstitial keratitis.

Sclerosing keratitis is the major cause of blindness due to onchocerciasis which results from chronic infection with the filarial parasite Onchocerca volvulus. Using a murine model of onchocercal sclerosing keratitis, we have demonstrated previously that predominantly (> 85%) CD3 + /CD4+ T-cells as well as the IL-2 receptor bearing cells infiltrate into the cornea in vivo during development and progress of the disease. The identification of CD4+ subsets TH1 and TH2 based on the cytokine secretion patterns of murine T-lymphocytes has been useful for understanding the immune basis of resistance and pathogenesis in murine models of several parasitic diseases. The present investigation was carried out to demonstrate whether the local immune response at the corneal lesion due to onchocercal interstitial keratitis correlated with such distinct patterns of cytokine production. For that purpose, mRNA was extracted separately from corneas obtained from the diseased eyes and the normal eyes of A/J mice with onchocercal interstitial keratitis, reverse transcribed and amplified by the polymerase chain reaction with four different cytokine specific primers. In corneas obtained from the eyes affected with onchocercal interstitial keratitis, mRNAs coding for IL-4 and IL-5 were up-regulated compared to the normal eyes having no lesions from the same animals. However, the levels of mRNAs for IL-2 and IFN gamma were found to be the same in the diseased and normal eyes. Taken together, these data suggest that IL-4 and IL-5 producing TH2-lymphocytes are active at the corneal lesion due to onchocercal interstitial keratitis.

Semiquantitative measurement of cytokine messenger RNA in endomyocardium and peripheral blood mononuclear cells from human heart transplant recipients.

BACKGROUND: Cytokines play a central role in inflammatory responses and in specific immune responses directed toward alloantigens. The pattern and quantity of cytokines produced in graft rejection can yield valuable information regarding the cellular and molecular mechanisms of the antigraft response. METHODS: We used the polymerase chain reaction to semiquantitatively measure changes in the amount of messenger RNA from the interleukin-1 beta, interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumor necrosis factor-alpha, interferon-gamma, interleukin-1 receptor antagonist, and the interleukin-2 receptor genes in the peripheral blood and endomyocardium of cardiac allograft recipients during the first 8 weeks after transplantation. A total of 328 samples of resting (n = 251) and stimulated (n = 77, stimulated with phytohemagglutinin and lipopolysaccharide for 18 hours) peripheral blood mononuclear cells collected from 16 patients were measured. To measure intragraft cytokine levels, we analyzed 150 endomyocardial biopsy specimens from 19 patients. RESULTS: No elevation in expression was seen before injection, but, after the onset of rejection and concomitant with treatment, there was a decrease in detectable mRNA (p < 0.05) for the pro-inflammatory monokines interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha in resting peripheral blood mononuclear cells, and a decrease for the T-cell derived cytokines interleukin-4 and interleukin-10 in stimulated peripheral blood mononuclear cells. These changes in mRNA expression occurred coincidentally with decreases in the percentage of lymphocytes and monocytes in the peripheral blood after administration of rejection therapy. In endomyocardial biopsy specimens, there were no detectable changes in the quantities of cytokine mRNA specimens for the interferon-gamma, interleukin-6, interleukin-10, interleukin-1ra, and interleukin-1 beta genes before rejection. In general, the levels of these cytokines were near the lower limits of detection by our assay in endomyocardial biopsies, mRNA from the interleukin-2, interleukin-4, tumor necrosis factor-alpha, and interleukin-2R genes were undetectable. CONCLUSIONS: We conclude that changes in the expression of cytokine mRNA in both peripheral blood mononuclear cells and endomyocardial biopsy specimens as measured by the semiquantitative polymerase chain reaction method used in this study does not effectively predict rejection. The decline in peripheral blood mononuclear cell cytokine mRNA after rejection treatment is likely due to changes in the proportion of lymphocytes and monocytes in the peripheral blood in concert with a steroid-induced downregulation by cytokine gene transcription.

Tumor necrosis factor alpha gene expression in human peritoneal macrophages is suppressed by extra-abdominal trauma.

BACKGROUND: Trauma is believed to activate immunocytes but paradoxically also increases the risk of intraperitoneal infection. OBJECTIVE: To investigate these events by evaluating changes in the cytokine control networks of human peritoneal macrophages (PM phi) early after trauma. DESIGN: Case-control study comparing cytokine messenger RNA (mRNA) expression by PM phi from patients with extra-abdominal trauma with that of both peripheral blood mononuclear cells (PBM) and PM phi obtained from healthy individuals. SETTING: Level I trauma center and basic science laboratory in a university hospital center. PATIENTS: Six patients with polytrauma (Injury Severity Score, > or = 15) with clinically negative diagnostic peritoneal lavages performed on routine indications at admission to the emergency department and six healthy age- and sex-matched individuals undergoing inguinal herniorrhaphy under local anesthesia. INTERVENTIONS: Peritoneal macrophages were isolated from diagnostic peritoneal lavages in trauma patients. Identical lavages were performed through the hernia sac in the control group. MEASUREMENTS: Cellular RNA was assayed for tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta, IL-6, and IL-10 message by semiquantitative reverse-transcription polymerase chain reaction. RESULTS: Normal PM phi expressed high levels of TNF-alpha mRNA relative to PBM, but expression of the other proinflammatory cytokines was equivalent to that of PBM. Peritoneal macrophage expression of TNF-alpha mRNA was markedly (64-fold) decreased after trauma (P < .001), when PBM expression of IL-10 mRNA was increased (P = .03). CONCLUSIONS: Human PM phi constitutively show high levels of TNF-alpha message expression, and this is down-regulated by polytrauma. This might constitute a functionally "primed" state. If so, TNF-alpha down-regulation might contribute to functional PM phi suppression after systemic injury.

Human peripheral mononuclear cells do not show proinflammatory patterns of cytokine transcription in early trauma: a preliminary report.

Injury has been hypothesized to cause inflammation through systemic release of lipopolysaccharide and pro-inflammatory cytokines, but this has proved difficult to demonstrate in humans. We looked for evidence of an inflammatory pattern of cytokine gene expression by peripheral blood mononuclear cells (PBM) in six polytraumatized patients (ISS = 25 +/- 8) upon ER admission, and in six matched healthy controls. PBM tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-4, IL-6, IL-10, and interferon (IFN)-gamma message was assessed by semi-quantitative reverse-transcription polymerase chain reaction. No increase in expression of any of the pro-inflammatory cytokines (tumor necrosis factor-alpha, IL-1 beta, or IL-6) was found after trauma, and IFN-gamma tended to decrease. Of the immunosuppressive cytokines, IL-10 expression increased 5-fold (p < .05) but no change in IL-4 was discerned. This pattern is fundamentally different from the cytokine expression patterns expected with sepsis or exposure to lipopolysaccharide. These findings are inconsistent with the occurrence of systemic endotoxemia and subsequent global immunocyte activation early after trauma.

Differences in intraepithelial lymphocyte T cell subsets isolated from murine small versus large intestine.

Intraepithelial lymphocytes (IELs) have been extensively studied in the murine small intestine. However, to date no studies have assessed IEL in the large intestine, despite the marked differences in function and lumenal environment. In the present study, we isolated IEL from both small and large intestine of three mouse strains (BALB/c, C3H/HeN, C57BL/6) and determined the frequency of CD2, CD4, and CD8 expression on CD3+ IEL, as well as the frequency of alpha beta and gamma delta TCR usage and V beta distribution. Higher numbers of IEL/unit length were always isolated from the small intestine (20-30 x 10(6)/5 mice) compared with large intestine (1.1-2.5 x 10(6)/5 mice). Interestingly, IEL from the large intestine of all strains were predominantly alpha beta TCR+ whereas gamma delta TCR+ IELs predominated in small intestine. Large intestinal IELs were mainly CD4+, in both BALB/c and C3H/HeN mouse strains. IELs from large intestine of C57BL/6 mice were mainly CD8+; however, the CD4+ subset was fourfold higher when compared with small intestine IEL. Potential functional differences between IEL subsets was assessed by determining the relative levels of mRNA for IL-1, 2, 4, 5, 10, IFN-gamma, TGF-beta, and TNF-gamma. Similar patterns of IL-1, IFN-gamma and TNF-alpha were seen while more IL-2, IL-4, IL-5, and IL-10 mRNA was noted in large intestinal IEL. Stimulation of C3H/HeJ IEL with anti-CD3 also resulted in higher levels of IL-3/GM-CSF, IL-4, and IL-6 by IEL from large intestine. These results show that marked differences occur among the T cell subsets present in IELs from mouse small and large intestine.

Donor specific bone marrow cells suppress lymphocyte reactivity to donor antigens and differentially modulate TH1 and TH2 cytokine gene expression in the responder cell population.

Previous studies have shown that post-transplantation infusion of donor specific bone marrow following a non-specific potent immunosuppressive agent such as antilymphocyte globulin (ALG) can significantly enhance graft survival compared to ALG alone. This enhancement remains variable and is thought to occur through the induction of specific partial tolerance to the renal allograft, but the underlying cellular mechanisms have not been clearly identified. In order to improve the efficacy of this specific immunosuppressive treatment and to study the events leading to enhanced allograft survival, we sought to establish a simple in vitro model based on a mixed lymphocyte reaction (MLR). We show that cellular proliferation seen in a normal MLR can be suppressed by addition of donor specific bone marrow cells (BMC). Significantly, this suppression is not observed with either third party BMC or donor specific peripheral blood mononuclear cells (PBMC). We have defined the optimum conditions of bone marrow infusion regarding number of BMC, their handling and culture, and simple enrichment procedures. Using a semiquantitative polymerase chain reaction assay, we have studied the cytokine gene expression in MLR modulated by donor specific BMC. In an unmodified allogeneic response, the responder cells show increased expression of interleukin-2 (IL-2) gamma-interferon IFN-gamma and receptor (IL-2R) mRNA, and no IL-10 mRNA. When responder cells are cultured with BMC of the stimulator, there is a 256-fold decrease in IL-2 mRNA, and a 64-fold decrease in IFN-gamma and IL-2R mRNA. There is also a 64-fold increase in IL-10 mRNA. This effect is even more marked when the BMC are depleted of CD3+ cells. The kinetics of addition of donor specific BMC to the normal allogeneic MLR culture and specificity of the action of BMC are also elucidated. Our data suggest that the enhancement of graft survival observed with donor BMC may operate through decreased proliferation of reactive T cell clones (due to decreased IL-2/IL-2R) and suppressed monocyte functions (due to decreased IFN-gamma and increased IL-10 gene expression).

Expression of E-selectin messenger RNA and protein in rheumatoid arthritis.

OBJECTIVE: To examine the de novo synthesis and cellular distribution of the E-selectin adhesion molecule in synovial tissues obtained from patients with rheumatoid arthritis (RA). METHODS: Immunohistochemistry techniques combined with in situ hybridization were used to examine RA synovium. RESULTS: There were numerous endothelial cells positive for E-selectin and E-selectin messenger RNA in the RA synovial membranes. Moreover, E-selectin expression appeared to correlate with inflammatory activity. CONCLUSION: The strong vascular expression of E-selectin indicates an activation of endothelial cells in the recruitment of cells associated with the chronic inflammation of RA.

Peyer's patch CD8+ memory T cells secrete T helper type 1 and type 2 cytokines and provide help for immunoglobulin secretion.

Analysis of cytokine gene expression by reverse transcription-polymerase chain reaction (RT-PCR) demonstrated high spontaneous levels of transcripts for multiple cytokines in murine Peyer's patches (PP) compared to spleen and peripheral lymph nodes. This is consistent with the presence of active germinal centers in PP and their continuous exposure to lumenal antigen including bacterial endotoxin. RT-PCR analysis of cytokine transcripts in purified PP T cell populations revealed the presence of transcripts for interleukin-4 (IL-4), IL-5 and IL-10 in addition to interferon-gamma (IFN-gamma) in CD8+ cells purified by flow cytometry. The majority of PP CD8+ T cells were also CD45RBlo (MB23G2-), suggesting that these cells were activated/memory cells. CD8+ cells in spleen and mesenteric lymph nodes (MLN) were predominantly CD45RBhi (MB23G2+) consistent with a resting/naive phenotype. PP and MLN CD8+ T cells also secreted IL-5 and IL-10 when stimulated with anti-CD3 monoclonal antibody and when co-cultured with PP B cells enhanced secretion of both IgG and IgA. These studies suggest that CD8+ T cells at mucosal sites secrete T helper type 2 cytokines and can provide functional help for B cells in these tissues.

The cell and molecular basis of leukocyte common antigen (CD45)-triggered, lymphocyte function-associated antigen-1-/intercellular adhesion molecule-1-dependent, leukocyte adhesion.

We recently reported that cross-linking the leukocyte common antigen (CD45) can rapidly induce aggregation of human peripheral blood mononuclear cells via lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) interactions. Herein, we have examined both T-cell--monocyte cellular interactions and the molecular signaling that are involved in this phenomenon. Experiments using highly purified T lymphocytes showed that CD45-induced aggregation requires the presence of both T cells and monocytes. Cross-linking CD45 only on T lymphocytes, but not on monocytes, initiated cellular clustering after reconstituting to the respective untreated cell type. By several criteria, CD45-induced clustering of T cells to autologous monocytes was shown to be Fc-receptor--independent. When comparing intracellular signaling in leukocyte aggregation induced by CD45 cross-linking versus phorbol myristate-12-13-acetate (PMA) treatment, the former was found to be fivefold to 10-fold more sensitive to H-8, a reagent that effectively blocks cAMP- and cGMP-dependent protein kinases. On the other hand, reagents that increase intracellular cAMP levels (eg, dbcAMP, forskolin, and IBMX), protein kinase C (PKC) inhibitors (eg, staurosporine), and tyrosine kinase inhibitors (eg, herbimycin A and genistein) all readily inhibited PMA-induced, but not CD45 monoclonal antibody-induced, aggregation. We conclude that cross-linking the leukocyte common antigen on T cells induces LFA-1--/ICAM-1--dependent T-cell--monocyte aggregation through a unique signaling pathway independent of PKC, which involves instead cAMP-/cGMP-dependent protein kinases.

IL-2, IL-4, and IFN-gamma gene expression versus secretion in superantigen-activated T cells. Distinct requirement for costimulatory signals through adhesion molecules.

In the complete absence of APCs staphylococcal superantigens induced IL-2, IL-4, IL-5, IFN-gamma, and IL-2R gene transcripts in both highly purified human T cells and FACs sorted CD4+ memory (CD45RA-) T cells. Secretion of IL-2, IL-4, and IFN-gamma, as well as DNA synthesis, on the other hand, required the presence of monocytes. At cytokine gene transcript level, three patterns of expression were noted after superantigen activation of T cells in the presence vs the absence of APC. mRNA levels for IL-2 were markedly up-regulated in the presence of monocytes, IL-4 and IFN-gamma transcripts increased only modestly, and IL-5 and IL-2R mRNA levels were unaffected. Blocking mAbs against LFA-1 and LFA-3 added to staphylococcal enterotoxin B (SEB)-activated cultures of T cells and autologous monocytes, reproducibly decreased both T cell proliferation and genetic expression of IL-2, IL-4, IL-5, and IL-2R, although having little or no effect on IFN-gamma transcripts. Further, under those conditions of blocking, secretion of IL-2 and IL-4 was dramatically decreased, whereas IFN-gamma secretion remained essentially unchanged. In contrast, LFA-1 and LFA-3 mAbs completely abrogated IFN-gamma secretion from PHA-activated T cell-monocyte mixtures, although having no inhibitory effect on T cell proliferation. These results indicate a characteristic and differential involvement of adhesion molecule-mediated signals in superantigen-induced T cell proliferation, differential cytokine gene expression, and cytokine secretion.

The Mycobacterium tuberculosis 71-kDa heat-shock protein induces proliferation and cytokine secretion by murine gut intraepithelial lymphocytes.

Murine intraepithelial lymphocytes (IEL) respond poorly to T cell mitogens and to monoclonal antibody stimulation of T cell receptor (TCR)- and CD3- associated molecules. In contrast, we found that a soluble extract of Mycobacterium tuberculosis (Mtb), but not purified protein derivative of tuberculin, induced significant proliferative responses in IEL cultures. The active component was apparently a heat shock protein (HSP), since recombinant 71-kDa HSP from Mtb induced IEL to proliferate, while 65-kDa HSP from M. bovis and M. leprae did not. Both alpha/beta and gamma/delta TCR-enriched IEL gave proliferative responses to 71-kDa HSP. Further, culture supernatants from IEL stimulated with 71-kDa HSP contained elevated levels of interleukin-(IL)-3/granulocyte-macrophage colony-stimulating factor, interferon-gamma and IL-6, but not IL-2, IL-4, IL-5 or transforming growth factor-beta. Finally, several IEL T cell clones have been maintained for up to 6 weeks, when stimulated with 71-kDa HSP, IL-2 and feeder cells. Our results show that the 71-kDa HSP of Mtb induces IEL T cells to divide and to secrete cytokines and this may offer a model for cloning and study of IEL T cells in vitro.