Role Of Histocompatibility Antigens Research Articles

HLA antigens and resistance to HIV.

The role of histocompatibility antigens in HIV infection has been investigated by several approaches. Thus the haplotype A1B8DR3 that is usually linked to autoimmune disorders seems to be associated with accelerated progression to AIDS. Cross-reactivity between MHC antigens and HIV-1 proteins is evident from alloimmunization experiments in mice and xenoimmunization of monkeys with human cells. Furthermore, recent reports suggest that some individuals with uncommon HLA antigens may be resistant to HIV infection. In addition to expressing cross-reacting antigens with HLA, HIV also exhibits substantial amounts of host beta-2 microglobulin and HLA-DR attached to its surface. Taken together, these data are stimulating new hypotheses relevant for AIDS pathogenesis. Based on alloimmunization, novel approaches have also been proposed in attempts to promote an effective immune response to HIV.

The role of histocompatibility antigens in transplantation of isolated islets of Langerhans in the rat.

In a model of congenic and intra-MHC recombinant rat strains, the differential role of various histocompatibility antigens in renal subcapsular transplantation of purified islets of Langerhans is evaluated. Class I MHC antigens of the RT1.A region, expressed on the endocrine cells of the islets themselves, do not induce graft rejection on their own. MHC class I antigens as encoded by the RT1.C region do not induce rejection either. MHC class II antigens as encoded by the RT1.B/D region are not expressed on the endocrine pancreas, not even during rejection. Although interstitial dendritic cells situated within the islets express these antigens, an isolated RT1.B/D incompatibility of islets is associated with prolonged survival in contrast to rapid rejection of fully MHC-mismatched grafts. Unlike other organs, islets matched for all MHC antigens, but incompatible at minor histocompatibility antigens, undergo rejection early after transplantation.

The role of histocompatibility antigens in transplantation of isolated islets of Langerhans in the rat

The role of histocompatibility antigens in transplantation of isolated islets of Langerhans in the rat

Impact of histocompatibility antigens on pregnancy outcome

The role of histocompatibility antigens in pregnancy outcome is controversial. This controversy may be because the initial studies were of small numbers or the patient groups were not homogeneous. The purpose of this study is to clarify these discrepant results by carrying out histocompatibility antigen typing and mixed lymphocyte culture on couples with idiopathic recurrent spontaneous abortion and by comparing results with those of fertile couples. Sixty couples with at least three spontaneous abortions and 60 normal couples with at least two successful pregnancies were included. Histocompatibility antigen typing and mixed lymphocyte culture were performed by using the standard techniques. The data were analyzed statistically with the Fisher exact test and chi 2. Our results failed to show any difference between normal and aborting couples with regard to HLA-A, HLA-B, and HLA-DR distribution or sharing or to mixed lymphocyte culture responsiveness. Our study, along with other studies, emphasizes that the histocompatibility antigen system does not have an impact on pregnancy outcome.

Immunologic Heterogeneity Among Potential Transplant Recipients: Prospects for Predicting Immune Responses to Allografts with In Vitro Tests

The ability to accurately predict the response of a specific patient to a specific organ allograft has long been a goal of organ transplantation. The role of histocompatibility antigens in determining the acceptance or rejection of an allograft-recipient combination has been thoroughly investigated, but is being reevaluated as improved immunosuppressive agents become available. Early efforts at immunologic monitoring are reviewed in addition to more recent efforts that focus on the cellular and molecular mediators of immunity. The authors' own experience with lymphokine measurements in clinical transplantation is also reviewed, with emphasis on the role of interleukin-2 (IL-2) and its soluble receptor (IL-2R) in various transplant-associated conditions. The authors conclude that information useful in the management of transplant patients may be derived from serial measurements of IL-2 and IL-2R, but that infections, especially CMV, may not be ruled out with certainty by these measurements alone. The available data suggest that study of additional lymphokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) may be useful in discriminating rejection from infections in transplant patients.

The role of histocompatibility antigens in cell‐mediated cytotoxicity against marek's disease tumour‐derived lymphoblastoid cell lines

The cytotoxic activity of spleen cells from Marek's disease (MD) virus-infected chickens against syngeneic and allogeneic tumour cell lines was compared, using MD lymphoma-derived lymphoblastoid cell lines obtained from two inbred and two outbred chicken strains. Activity was significantly greater against allogeneic than against syngeneic target cells, although some activity against syngeneic cells was detected. Cold target cell inhibition tests confirmed that unlabelled normal spleen cells could block the cytolysis of tumour cell targets bearing the same histocompatibility antigens as the spleen cells. It was concluded that the tumour-specific antigens against which the effector cells were reacting may be modified histocompatibility antigens and that the enhanced cytotoxicity seen with allogeneic target and effector cells may be an artefact analogous to an adjuvant effect.

Distribution of beta2 microglobulin and HLA in chorionic villi of human placentae.

ANALOGIES are often made between transplantation and placental immunology. The role of histocompatibility antigens is of undisputed importance in transplantation immunology but it is not clear whether such antigens are important in pregnancy. Indeed, it is not known whether trophoblasts manifest histocompatibility antigens. If HLA antigens are relevant in pregnancy, it is of central importance to know if trophoblasts have these antigens. This is a difficult problem because human anti-HLA sera often contain other antibodies, and heterologous anti-HLA sera often lack precise HLA specificity1. But HLA has been shown to be invariably associated with β2-microglobulin2, and here we present data in support of the concept that human trophoblasts contain neither β2 microglobulin nor HLA. Also, treatment with several enzymes has failed to reveal these antigens. In addition, we have not been able to identify either β2 microglobulin or HLA on trophoblasts from 6-week or 13-week placentae or on placental tissues maintained in vitro for 5 d.