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S M Krams

Publications and source records attributed to S M Krams.

49 records · Page 3Linked to original sources
PubMed1993

Evidence for a nonclassical pathway of graft rejection involving interleukin 5 and eosinophils.

The role of IL-5 and eosinophils in allograft rejection was studied in human liver allograft recipients. Liver allograft biopsies were analyzed for intragraft IL-5 gene expression, and the percentages of eosinophils and plasma cells within the portal infiltrate as well as peripheral eosinophil levels were determined. The majority of allografts with evidence of rejection had concomitant IL-5 mRNA and eosinophilia, while no resolving or nonrejecting allografts had simultaneous IL-5 mRNA and eosinophilia. In fact, rejecting liver allografts that contain IL-5 mRNA and eosinophils also contain infiltrating cells that produce the cytotoxic mediator major basic protein. In contrast, intragraft plasma cell and peripheral eosinophil levels did not correlate with the histopathologic status of the allograft. Cyclosporine and FK506 had similar effects on the frequency of IL-5 gene expression in rejecting and nonrejecting allografts. However, OKT3 appeared to profoundly modulate IL-5 gene expression, since 0 of 11 biopsies obtained during OKT3 treatment for rejection contained IL-5 transcripts. These observations raise the possibility of a cellular pathway of liver allograft rejection mediated by IL-5-activated eosinophils.

Base Sequence↗
PubMed1993

IL-2 and IL-5 gene expression in response to alloantigen in liver allograft recipients and in vitro.

IL-2 and IL-5 gene expression in response to alloantigen was studied in liver allograft recipients and in an in vitro system. Seventy-seven sequential liver allograft biopsies from 22 patients were analyzed for IL-2 and IL-5 mRNA by polymerase chain reaction and Southern blot hybridization. Message for IL-5 was present in 74% of allografts with rejection, 46% of allografts with resolving rejection, and 33% of allografts with no evidence of rejection. The frequency of IL-5 transcripts in rejecting allografts was significantly different than the frequency of IL-5 transcripts in grafts without evidence of rejection (P = 0.003). Message for IL-2 was detected in 29% of rejecting allografts, 18% of allografts without evidence of rejection, and 43% of allografts with resolving rejection. There was no significant association between IL-2 gene expression and the histopathological status of the allograft. Interestingly, 9 of 15 biopsies that contained IL-2 message in the no rejection and resolving rejection categories went on to display rejection shortly thereafter. IL-2 and IL-5 gene expression rarely occurred simultaneously within allografts. An in vitro system consisting of irradiated, allogeneic stimulator cells and normal peripheral blood mononuclear cells as responders was established to further investigate alloantigen-driven IL-2 and IL-5 production. Both IL-2 and IL-5 were produced in response to alloantigen as determined by specific bioassays. Maximal levels of IL-5 activity in culture supernatants generally followed maximal IL-2 levels by 24 hr, but both IL-2 and IL-5 production were dramatically inhibited by CsA. Analysis of cytokine gene expression revealed that IL-2 transcription peaked within the initial 24 hr of culture, whereas IL-5 transcription was maximal at 120 hr of culture. The expression of a CTL-specific serine esterase gene was similar to IL-5 in that it was maximal during the latter phases of the culture period. Thus, both human IL-2 and IL-5 are produced in response to alloantigen and are inhibitable by CsA. These data suggest that IL-2 and IL-5 may participate in cellular pathways of tissue damage within the rejecting allograft.

Base Sequence↗
PubMed1993

New immunologic insights into mechanisms of allograft rejection.

Our current understanding of liver allograft rejection indicates that multiple cellular interactions, involving a variety of cell-associated and soluble mediators, are critical to the response. The extravasation and localization of recipient immune cells to the allograft is dependent on recognition and interaction of complementary adhesion molecules expressed on circulating leukocytes and endothelium. Similar receptor-ligand pairs can also augment the binding of effector cells to target tissue within the allograft. Inflammatory mediators such as IL-1, IL-6, TNF-alpha, and IFN-gamma produced within the allograft can increase the local expression of adhesion molecules and thereby promote the entry of specific and nonspecific cells. The TCR expressed on T lymphocytes has the potential to recognize MHC antigens expressed on the allograft in many different forms. Thus, the T cell response to graft-associated alloantigens appears to be complex and dynamic. The production of T cell-derived cytokines is central to the activation and maturation of effector cells within the allograft. The identification of cytotoxic mediators such as serine protease and MBP within rejecting human allografts supports the role of cytotoxic T cells and eosinophils as effector cells. Undoubtedly, the development of genetically manipulated animal models will serve to further elucidate our understanding of the cellular mechanisms of graft rejection.

Animals↗
PubMed1992

Cytokine and T cell receptor gene expression at the site of allograft rejection.

Intragraft cytokine and T cell receptor gene expression was analyzed in rejecting renal allografts by polymerase chain reaction (PCR). Message for IL-1 beta, IL-6, and TNF-alpha was detected in nephrectomy tissue with pathological evidence of acute or chronic rejection. Similarly, mRNA for both IL-6 and TNF-alpha was present in renal biopsies from acute rejecting kidneys. IL-2R, IL-4, and IL-5 mRNA was present in both rejecting and rejected kidney allografts, indicating that these cytokines may play a role in ongoing renal allograft rejection. Conversely, IL-2, IL-7, and IFN-gamma message was detected infrequently. In order to address the diversity of T cells in rejecting kidneys, we have analyzed the clonality of the TcR present within the allograft tissue. Rearranged TcR genes were identified in all allografts examined (n = 16) indicating the presence of T cells bearing the alpha/beta TcR. We have determined that there is a heterogeneous infiltration of T cells in the rejected allograft with TcR representing x = 7.47 +/- 2.4 families rearranged in samples obtained from nephrectomies, whereas x = 5.33 +/- 0.58 families were detected in samples obtained from biopsy tissue. These data indicate that (1) cytokines are produced locally which may contribute to graft cell destruction, (2) the heterogeneity of intragraft T cells during kidney allograft rejection may exist because nonspecific lymphocytes have been recruited to the site by locally produced cytokines or because T cells are responding to multiple epitopes or multiple donor antigens. Detection of intragraft cytokines and TcR may prove useful in elucidating the mechanism of rejection and therefore lead to improved immunosuppression.

Adolescent↗
PubMed1992

Intragraft cytokine profile during human liver allograft rejection.

Forty-three human liver allograft biopsies and normal liver were directly analyzed for inflammatory and immunoregulatory cytokine gene expression by polymerase chain reaction (PCR). IL-5 gene expression was predominantly present in biopsies from liver allografts with histopathological evidence of acute rejection. IL-2 gene expression was rarely observed in rejecting allografts or allografts without evidence of rejection. In contrast, IL-4 message was readily detectable in the majority of liver allografts regardless of clinical status. The inflammatory mediators IL-1 beta, TNF-alpha, and IL-6 were detected with similar frequency in rejecting allografts and allografts without evidence of rejection. These findings suggest that inflammatory and immunoregulatory cytokines are produced within the allograft. Moreover, IL-5 may play a role in the local mechanisms of liver allograft rejection.

Base Sequence↗
PubMed1990

Analysis of hepatic T lymphocyte and immunoglobulin deposits in patients with primary biliary cirrhosis.

The histological findings in patients with primary biliary cirrhosis have been well-defined and are often used in the clinical staging of disease. However, it has only been with the development of reagents that phenotypically characterize the lymphoid infiltrate that attempts have been made to correlate pathophysiology with immune effector populations. Indeed, the inflammatory hepatic lesions in primary biliary cirrhosis have been described as containing CD4-positive and CD8-positive T cells. Less clear, however, have been the T cell receptors in these lesions. Further, the data on immunoglobulin deposits in hepatic lesions have been less well-defined; this deficit may be a result of the quality of polyspecific sera and difficulties in background. To address these issues, we have used a battery of well-defined monospecific and polyspecific reagents to phenotypically define the occurrence of lymphoid cells in the livers of patients undergoing transplantation. Furthermore, we have defined these same markers on T cell lines derived from liver, regional lymph node and peripheral blood. The predominant cell type in the mononuclear infiltrate is the CD3+, CD4+ T lymphocyte bearing the T cell receptor alpha beta. T cell lines from the same patients demonstrate similar findings. Of special importance, however, was the detection of CD20+ B cells and Ig+ cells in the lymphoid infiltrate. Indeed, we also readily demonstrated the presence of immunoglobulin on the surface of biliary epithelium. These data suggest that mechanisms involved in the pathophysiology of primary biliary cirrhosis may include both T cell and antibody mechanisms. The results also underscore the need to develop a functional, and not just a phenotypical, assay of the inflammatory infiltrate.

Antibodies, Monoclonal↗
PubMed1989

Generation of biliary lesions after transfer of human lymphocytes into severe combined immunodeficient (SCID) mice.

Human PBL have been reported to reconstitute B and T cells as well as human serum Ig in mice with severe combined immunodeficiency disease (SCID). To confirm these observations and attempt the transfer of an autoimmune disease to the immunodeficient animals, groups of SCID mice received an injection of PBL from patients with primary biliary cirrhosis (PBC) or from normal volunteers. By 8 wk after the injection of 10-42 x 10(6) PBL into the mice, human lymphoid cells were detected in the spleen of approximately half of the animals and all had detectable serum levels of human IgG. Moreover, the sera of SCID mice that received cells from patients with PBC contained human antimitochondrial antibodies (AMA) to dihydrolipoamide acetyltransferase, the major mitochondrial autoantigen of PBC. Histologically, a human mononuclear cell infiltrate was present around the portal areas of the liver and inflammation, bile duct atypica, and necrosis of bile duct cells were observed. While the biliary lesions in the SCID recipients of PBC cells were more severe, a mononuclear infiltrate was clearly evident in mice that received cells from normal donors, suggesting the presence of a graft-vs.-host-like disease. While these data are the first to describe an animal model with both the humoral and cellular characteristics of PBC, they also raise an interesting question regarding the preferential localization of lymphoid cells to the biliary system.

Animals↗
PubMed1989

Immunization of experimental animals with dihydrolipoamide acetyltransferase, as a purified recombinant polypeptide, generates mitochondrial antibodies but not primary biliary cirrhosis.

The availability of recombinant mitochondrial autoantigens may permit the experimental study of the pathophysiology of primary biliary cirrhosis. Previously, we demonstrated that high-titer antibodies to the 74 kD mitochondrial autoantigen dihydrolipoamide acetyltransferase could be generated when BALB/c mice were immunized with purified recombinant protein. Based on these data, we attempted an 8-month study to induce antibodies and liver dysfunction by immunizing AKR/J, C3H/J and CBA/HeJ mice as well as rats, guinea pigs, rabbits and rhesus monkeys with purified recombinant human dihydrolipoamide acetyltransferase. Antibodies to dihydrolipoamide acetyltransferase were readily induced and detected in all species of experimental animals with species and strain differences in the titer of the responses. Of particular interest, rabbits and guinea pigs produced antibodies which were specifically reactive with the functional site of dihydrolipoamide acetyltransferase, whereas the other strains and species produced antibodies to other epitopes on the molecule. Finally, similar to data on humans with primary biliary cirrhosis, the pyruvate dehydrogenase enzyme pathway was inhibited in the presence of immunized animal sera. These data imply that features other than simply an antibody response to mitochondrial enzymes are required for the development of primary biliary cirrhosis. Further studies will be necessary to determine the mechanisms by which mitochondrial proteins elicit an immune response.

Acetyltransferases↗
PubMedDate not supplied

Characterization of allograft rejection in an experimental model of small intestinal transplantation.

Graft rejection continues to be a major barrier to the success of clinical small intestinal transplantation. The objective of this study was to characterize histopathologic and immune parameters of allograft rejection in an experimental model of small intestinal transplantation. Heterotopic intestinal transplants were performed in allogeneic and isogeneic rat strain combinations. An additional group of allogeneic recipients was treated with tacrolimus (1 mg/kg/day) for 7 days beginning on posttransplant day 1. Recipients of allografts and isografts were killed on days 1 to 7 following transplantation, and tacrolimus-treated allograft recipients were killed on days 4 and 7. Grafts and native intestines were examined for histopathology and cytokine gene expression. Very early rejection was observed on posttransplant day 3 and severe rejection was apparent by day 7. The key histopathologic features of acute graft rejection including apoptosis, crypt epithelial cell injury, and an inflammatory infiltrate were uniformly identifiable on day 4 and progressed in severity through day 7. Interleukin (IL)-2, IL-4, IL-5, IL-6, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha mRNA were readily detectable in allografts on days 1 to 7. However, only IFN-gamma mRNA showed a significant early and sustained increase in allografts as compared to isografts and native intestine. Treatment of allograft recipients with tacrolimus abrogated the major histopathologic features of rejection and markedly inhibited IFN-gamma gene expression. These results indicate that graft rejection in small intestinal transplantation is characterized by a local and specific immune response marked by IFN-gamma production that results in crypt epithelial cell injury and apoptosis. Tacrolimus abrogates the histopathologic features of rejection in association with a marked inhibition of IFN-gamma gene expression.

Acute Disease↗
PubMedDate not supplied

T cell receptor usage by cytotoxic T lymphocytes against autologous human melanoma.

BACKGROUND: T cell receptor (TCR) usage by tumor infiltrating lymphocytes (TIL) represents the host's response to autologous melanoma (AM). The goal of this study is it determine TCR usage by cytotoxic T lymphocytes (CTL) against AM. MATERIALS AND METHODS: CTL were generated from three patients using lymphocytes from metastatic or tumor-draining lymph nodes by repeated in vitro sensitization (IVS). Total RNA was isolated from CTL and reverse-transcribed to cDNA. TCR usage was determined by polymerase chain reaction (PCR) using TCR primers. RESULTS: Cytolytic activity was non-specific within the first 2-4 weeks following IVS and TCR repertoire in these cultures revealed random V alpha and V beta gene usage. In contrast, by 6-10 weeks of culture, cytolysis was specifically directed against AM cells and such specific cytolysis was significantly correlated with TCR V alpha 1 (P < 0.001). CONCLUSION: TCR V alpha 1 is associated with a common restricted melanoma antigen.

Humans↗