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PubMed1976

The use of the IgG fraction of typing sera in the lymphocytotoxic test: a comparison with other cytotoxic methods.

The application of a simple batch method for the isolation of IgG from weakly lymphocytotoxic sera is described. The use of purified IgG as an antibody source at the serum concentration or up to tentimes that level resulted in the conversion of 25 out of 28 previously weak or non-reactive cytotoxic sera into potentially useful tissue typing reagents. The sensitivity of this technique was assessed by comparison with five cytotoxic test systems.

Cytotoxicity Tests, Immunologic↗
PubMed2000

Cytotoxically impaired transplant recipients can efficiently resist major histocompatibility complex--matched bone marrow allografts.

High rates of allograft rejection using T cell--depleted marrow or after transplantations into multiply transfused recipients have been reported. Together with current approaches to diminish host preparative immunosuppression before stem cell transplant, issues regarding the cells and effector pathways involved in resistance to progenitor cell presence in recipients are of increasing interest. The present investigation addressed questions concerning the contribution of cytotoxic effector mechanisms used by host cells involved in resistance to progenitor cell engraftment. A murine model was developed in which short-term resistance against major histocompatibility complex (MHC)-matched allogeneic T cell--depleted marrow was examined using a sensitive in vitro assay to detect progenitor cell presence by colony formation in vitro. Resistance was found to be dependent on previous priming to donor nonMHC antigens and could be transferred by a CD3+NK1.1- population. The resistance mechanism explicitly discriminated between donor and syngeneic progenitors after mixed marrow transplantation. Interestingly, the resistance was not impaired in animals unable to mediate cell-mediated cytotoxicity involving perforin-dependent or CD95L-dependent pathways. These results indicate that either cytotoxic effector pathway alone is sufficient to effect marrow allograft resistance or that non-perforin and CD95L effector mechanisms are responsible for barrier activity. The findings are discussed with respect to previous studies concerning T-cell involvement in resistance to MHC and hematopoietic histoincompatible-mismatched marrow grafts.

Animals↗
PubMed2005

Further evidence for an HLA-related recessive mutation in nasopharyngeal carcinoma among the Chinese.

We typed 247 cases of nasopharyngeal carcinoma (NPC), a disease predominantly of the southern Chinese, and 274 controls from the Chao Shan region of China's Guangdong province for HLA A and B. Besides confirming the established associations with A2, A33, B46 and B58 (positive associations) and A11 (negative association), the results demonstrated a number of rarer alleles with strong negative association with NPC. Our data, combined with those from the previous studies in Southern Chinese, displayed the protective effects for A31 (odds ratio (OR)=0.0; 95% confidence interval (CI)=0-0.11), B13 (OR=0.50; 95% CI=0.35-0.69), B27 (OR=0.49; 95% CI=0.25-0.92), B39 (OR=0.18; 95% CI=0.06-0.48) and B55 (OR=0.32; 95% CI=0.14-0.68), the ORs comparing individuals with or without each allele. Other ethnic groups do not display such large HLA-associated variation in NPC risk. We show that a linked NPC gene with dominant mode of action could not generate such large protective effects. The results provide strong supporting evidence for the existence of a southern Chinese specific, recessive NPC gene closely linked to the HLA region as a major determinant of the Chinese risk for the disease.

China↗
PubMed2001

Effects of major histocompatibility complex matching on graft survival in allogeneic rat limb transplantation.

Differences in the major histocompatibility complex (MHC) between recipients and donors present a problem because of immunologic responses in graft rejection. The purpose of this study is to clarify the efficacy of MHC matching against acute graft rejection of allogeneic limb transplants in rats. Right hindlimb transplantations were performed using various MHC-mismatched pairs of inbred rats. The rats were classified into 5 groups according to the differences in subregions of the RT1 (rat MHC) between the recipient and the donor: group 1, RT1-A,B,D barrier (the differences of RT1-A,B,D subregions); group 2, RT1-A barrier; group 3, RT1-B,D barrier; group 4, RT1-B barrier; and group 5, RT1-D barrier. The mean survival time significantly decreased in group 1 and increased in group 4. The results suggest that MHC matching clearly improves survival of transplanted limbs. Specifically, both RT1-A and D matching is the most effective compatibility in prolonging survival time of allogeneic limb transplants in rats.

Animals↗
PubMed1976

Anti-donor immune responses in prediction of transplant rejection.

We assessed various immune responses against donor tissue to determine their value in the diagnosis and prediction of clinical rejection episodes. Twenty-six consecutive clinical renal-transplant recipients were examined. Cell-mediated lymphocytotoxicity preceded and accompanied 41 of 45 rejection episodes (P less than 0.001). Complement-dependent antibody was present in 12 of 15 rejections (P less than 0.002)--four not accompanied by, and eight in association with, cell-mediated lymphocytotoxicity. Mixed lymphocyte reactivity or nonreactivity and inhibition by autologous serum occurred equally often in rejection and quiescence. Lymphocyte-dependent antibody occurred during both rejection episodes and quiescent phases, with a greater frequency during quiescence (P = 0.05). Cell-mediated lymphocytotoxicity was the best predictor of rejection (P less than 0.05). Cell-mediated lymphocytotoxicity was the best predictor of rejection (P less than 0.001), and was more easily suppressed by standard immunosuppressive therapy, than complement-dependent antibody. If specific cell-mediated lymphocytotoxicity, with or without antibody, recurred after rejection therapy, the graft underwent further rejection.

Antigen-Antibody Reactions↗
PubMed1972

Nature of the stimulating cell in the syngeneic and the allogeneic mixed lymphocyte reaction in mice.

Thymus cells from CBA and BALB/c mice are stimulated by syngeneic peripheral lymphoid cells in a "one-way" mixed lymphocyte reaction. The stimulating cell appears to be a mature B cell. Spleen cells from neonatal mice and thymus cells or bone marrow cells from adult mice are not able to induce DNA synthesis in syngeneic thymus cells, although they stimulate significantly allogeneic thymocytes. The ability of peripheral B cells to serve as stimulating cell in a syngeneic reaction develops with the age of the animal. The marginal stimulation of syngeneic thymus cells when 90% pure peripheral T cells were used as stimulating cells indicated that T cells alone were ineffective in stimulating in syngeneic mixed lymphocyte reaction. However they stimulated effective allogeneic thymocytes. On a cell-to-cell basis, light density splenic lymphocytes stimulated both syngeneic and allogeneic thymocytes better than did more dense lymphocytes. The data obtained suggest that stimuli other than those responsible for allogeneic stimulation induce proliferation of syngeneic thymus cells under identical culture conditions.

Age Factors↗
PubMed1973

Generation of cytotoxic lymphocytes in mixed lymphocyte reactions. I. Specificity of the effector cells.

Generation of cytotoxic effector cells by a unidirectional mixed lymphocyte reaction (MLR) in the mouse H-2 system was studied using labeled YAC (H-2(a)) leukemia cells as targets. The responding effector cell displayed a specific cytotoxic effect against target cells of the same H-2 genotype as the stimulating cell population. Killing of syngeneic H-2 cells was not observed, even when the labeled target cells were "innocent bystanders" in cultures where specific target cells were reintroduced. Similar results were found with spleen cells taken from mice sensitized in vivo 7 days earlier. The effector cell was not an adherent cell and was not activated by supernatants from MLR. The supernatants were not cytotoxic by themselves. When concanavalin A or phytohemagglutinin was added to the cytotoxic test system, target and effector cells were agglutinated. Under these conditions, killing of H-2(a) target cells was observed in mixed cultures where H-2(a) lymphocytes were also the effector cells. These findings indicate that specifically activated, probably thymus-derived lymphocytes, can kill nonspecifically once they have been activated and providing there is close contact between effector and target cells. Thus, specificity of T cell killing appears to be restricted to recognition and subsequent binding to the targets, the actual effector phase being nonspecific.

Animals↗
PubMed1973

Stimulus-response in the mixed lymphocyte reaction.

Mixed lymphocyte reactions occur when mouse spleen cell populations depleted of thymus-derived (T) lymphocytes are cultured with allogeneic target cells inactivated by mitomycin C or X irradiation, and when F(1) hybrid responder cells are cultured with inactivated parental target cells. These responses might be interpreted as indicating that T lymphocytes are not required for responsiveness and that F(1) lymphocytes recognize parental alloantigens. Data reported here indicate that the more likely explanation for these surprising results is that inactivated target cells recognize the "responding" cells and this recognition leads to the response observed.

Animals↗
PubMedDate not supplied

Organization of the canine major histocompatibility complex: current perspectives.

The dog is a valuable model for studying several human diseases as well as one of the most important models for organ transplantation. Important to understanding the pathophysiology or development of some of these diseases is an understanding of the canine major histocompatibility complex (MHC) or dog leukocyte antigen (DLA). Initial characterization of the DLA involved primarily cellular, serological, and biochemical analyses. Later a molecular analysis of the DLA region was begun. There are at least four complete class I genes: DLA-88, DLA-12, DLA-64, and DLA-79. DLA-88 is highly polymorphic, with more than 40 alleles obtained from an examination of 50 mixed breed dogs. The other class I loci are less polymorphic, with fewer than 12 alleles each. In the class II region there is one complete DRB gene called DLA-DRB1 with at least 24 alleles and one full-length DQB gene, DLA-DQB1, with 20 alleles characterized to date. DLA-DQA is less polymorphic with nine alleles and DLA-DRA appears monomorphic. Two highly polymorphic canine microsatellite markers, one located in the class I region and one located in the class II region, can be used to identify DLA-matched and -mismatched dogs within families for organ transplantation experiments. Future projects include mapping the DLA region by pulsed-field gel electrophoresis and using a recently constructed canine bacterial artificial chromosome (BAC) library to search for new genes within the DLA. The dog has been a useful model for understanding several human diseases such as gluten-sensitive enteropathy (Hall and Batt 1990), rheumatoid arthritis (Halliwell et al. 1972), narcolepsy (Tafti et al. 1996), and systemic lupus erythematosus (Lewis and Schwartz 1971, Teichner et al. 1990), as well as an important model for solid organ and hematopoietic stem cell transplantation (Storb and Deeg 1985). Much of the impetus behind efforts to characterize the canine MHC comes from its importance in transplantation. In spite of the dog's importance in studying human disease and in immunology, molecular analysis of the DLA has lagged behind that of the mouse and human as well as several agricultural animals.

Animals↗
PubMed1985

Vascularized bone allograft transplantation in a genetically defined rat model.

A heterotopic subcutaneous model for experimental vascularized bone allograft transplantation has been presented. This model uses genetically defined rats and allows serial assessment of graft viability. The reliability of this model has been proven by successful isograft transplantation. This model was used to study the effect of matching at the major histocompatibility complex on vascularized bone allograft survival. Whereas grafts transplanted across a minor histocompatibility barrier survived until sacrifice, grafts transplanted across a major histocompatibility barrier were victims of an acute rejection process. This study, therefore, showed genetic disparity to be a critical determinant of vascularized bone allograft survival. It indicates that primary vascularized bone allografts are as susceptible to rejection as heart and kidney allografts. For these reasons, it can be anticipated that genetic matching will be important in clinical vascularized bone allograft transplantation. The model used in this study should be useful for obtaining further fundamental immunologic information concerning vascularized bone allograft transplantation.

Animals↗