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In a series of 30 bone marrow grafts (in 29 recipients) from HLA-identical siblings for aplastic anemia, no correlation was demonstrated between rejection and pregraft HLA antibodies (P greater than 0.50). However, after grafting, HLA antibodies persisted in nine cases and graft rejection occurred, whereas in all but one of the remaining eight cases the HLA antibodies disappeared and a permanent engraftment was observed (P = 0.0008). These results suggest a relationship between engraftment and persistence or disappearance of HLA antibodies as an indication of the level of immunosuppression obtained with the conditioning regimen.

Twelve different HLA antisera, detecting antigens of both A and B series and the superspecificities w4 and w6, were tested for platelet-aggregating activity in 75 antiserum-platelet combinations. The correlation between the HLA specificities of the antisera and the aggregating effect on platelets carrying the corresponding antigens was significant (P = 0.011). Because the platelet aggregation test is being used for screening of circulating immune complexes, falsely positive reactions caused by HLA antibodies must be eliminated by adequate control experiments.

Immunological tests (lymphocyte response to phytohaemagglutinin, HLA antibody production, mixed lymphocyte reaction, HLA types and degree of matching) in women with severe pre-eclampsia show that their immunological activity is reduced or suggest that there is a high degree of immunological compatibility between mother and child. This hypoimmune response state is consistent with the epidemiological features of pre-eclampsia; and a relation might exist between the hypoimmune response and disorders of other systems in pre-eclampsia.

An indirect rosette assay which utilizes erythrocytes coupled with purified antiimmunoglobulin (Ig) antibodies was modified into a microassay for detecting HLA allo-and xenoantibodies. The test, which is performed in microtiter plates, is specific, reproducible and can handle large numbers of samples. As an inhibition assay the test can detect HLA antibodies even if mixed with antibodies to other cell surface structures. The rosette microassay is at least 10 times more sensitive than the complement-dependent microcytotoxic test and can use target cells which exhibit low viability or abnormal susceptibility to lysis.

In 52 conceptuses with known genomic origin, the HLA types expressed on whole villi and/or stromal cell cultures were compared with the HLA types of the patients. No preference for either HLA compatibility or incompatibility was found for androgenetic and paternally derived triploid conceptuses as a whole. Heterozygous, androgenetic, conceptuses, however, showed a trend towards preferential incompatibility, which may be of importance for their apparent greater risk for tropho-blastic tumour. HLA antibodies were found in 19.2% of the women, i.e. in the range reported for molar as well as non-molar pregnancies. Non-HLA antibodies reacting with lymphocytes of the spouse and/or cells from the conceptus were observed.

Inter-species reactive anti-IgG antibodies are disturbing in blocking and interference experiments with the sensitive mixed hemadsorption (MH) technique. By affinity chromatography this disturbance could be efficiently eliminated. Anti-IgG sera were passed through columns containing heterologous IgG. The absorption technique is rapid and simple. After one absorption the inter-species reactivity in anti-IgG sera had been decreased thousand-fold, while any loss of species-specific reactivity could not be detected. Such absorbed anti-IgG sera reacted only with homologous antibodies. The effect is exemplified with e.g. blocking of human HLA antibodies by anti-beta2-microglobulin from rabbits.

Donor-specific anti-HLA antibodies were studied by cytotoxicity crossmatching (CTXM) and flow cytometry crossmatching (FCXM) in 117 kidney transplant candidates; the same study was carried out in 33 cadaver-donor kidney recipients, during the first 3 post-transplant months, for which donor cells were available. Pre-transport evaluation showed that 82.9% of subjects were CTXM negative/FCXM negative, 6.8% of patients were positive in both tests, and 10.3% were CTXM negative/FCCM positive. Post-transplant monitoring for donor-specific antibodies (Abs-DS) showed that nine recipients (27.3%) were FCXM positive; six of them were IgG+ and three IgM+. In comparing these results with the clinical course, a significant association between FCXM IgG+ and rejection episodes was observed (P < 0.01).

Most predictive models and scores of graft survival in renal transplantation include factors known before transplant or at the end of the first year. They cannot be updated thereafter, even in patients developing donor-specific anti-HLA antibodies and acute rejection.We developed a conditional and adjustable score for prediction of graft failure (AdGFS) up to 10 years post-transplantation in 664 kidney transplant patients. AdGFS was externally validated and calibrated in 896 kidney transplant patients.The final model included five baseline factors (pretransplant non donor-specific anti-HLA antibodies, donor age, serum creatinine measured at 1 year, longitudinal serum creatinine clusters during the first year, proteinuria measured at 1 year), and two predictors updated over time (de novo donor-specific anti-HLA antibodies and first acute rejection). AdGFS was able to stratify patients into four risk-groups, at different post-transplantation times. It showed good discrimination (time-dependent ROC curve at ten years: 0.83 (CI95% 0.76–0.89).

Summary Pemphigoid gestationis (PG; herpes gestationis) is a rare autoimmune disease associated with pregnancy, currently defined by the presence of complement deposition along the cutaneous basement membrane zone. It is known to be associated with HLA-DR 3 and DR4, and an increase in anti-HLA antibodies in those with a history of PG has been reported. We have studied 39 patients with an immunofluorescence-confirmed diagnosis of PG for the presence and specificity of anti-HLA antibodies. Anti-HLA antibodies were found in all 39 patients. Specificity was against class 1 antigens in 98% (controls 10%: P>0.001) and class II antigens in 25% (controls 8.5%: P>0.001), Almost all anti- HLA antibodies were cytotoxic. The universal presence of anti-HLA antibodies in PG suggests that they may develop coincidently with anti basement membrane antibodies, and may reflect a common immunological event.

Une observation. Les anticorps anti-HLA specifiques contre le donneur disparaissent apres l'echange plasmatique et ne reapparaissent pas apres la transplantation renale, bien que d'autres anticorps anti-HLA reapparaissent

Patients with acute leukemia /AML and ALL/ who receive multiple transfusions of whole blood, platelets, or granulocytes, may develope anti-HLA immunisation in spite of chemotherapy. The frequency of HLA-alloimmunisation was studied in 10 children with ALL and in 3 with AML. HLA antibodies with multiple specificity were detected in 7 with ALL /70%/, and in all 3 with AML. The presence of these antibodies was associated with febrile transfusion reactions, and with immediate destruction of platelets or granulocytes. Selection of HLA compatible donors eliminated these reactions and permitted substitute therapy until a remission occurred. Therefore, as soon as anti-HLA immunisation is present, HLA compatible transfusions must be given.