HLA-DR2, a marker for class I antigen sensitization.

After analysis of 423 hemodialysis patients in a transfusion program and 461 cadaver-donor renal transplants, we found that HLA-DR2 frequency was significantly higher in the responder (36%) than in the nonresponder patient group (19%), according to the percentage of PRA (panel reactive antibodies). Among DR2+ patients, the percentage of hypersensitized patients was twice that of DR2- patients. Graft survival curves in cadaver-donor renal transplants indicated a significantly lower survival when recipients were DR2+, even in recipient-donor pairs identical for class II antigens but mismatched for class I antigens. The prognostic probability of low response to transfusions by a stepwise logistic regression analysis showed the influence of sex and DR2 phenotype. By multivariant discriminant analysis, we found that the DR2 phenotype was one of the most influential transfusion sensitization risk factors. Our preliminary conclusion is that DR2 can be related to immune responsiveness to class I antigens.

Immunological findings in immunoblastic lymphadenopathy. A detailed case study.

Several immunological parameters were investigated in a patient with immunoblastic lymphadenopathy (IBL). An increased concentration of polyclonal immunoglobulins, the presence of autoantibodies in the serum and an increased level of B lymphocytes with an abnormal DNA synthesis response to LPS in peripheral blood were the most salient features. The findings suggest that in IBL there is a numerical as well as a functional alteration of peripheral blood lymphocytes. We propose that the alteration was due to either an escape of lymphocytes from central lymphatic organs or a defect in maturation of peripheral blood lymphocytes.

HLA phenotype and haplotype frequencies in a sample of the Spanish population.

The frequencies of HLA antigens and genes were determined in 491 unrelated individuals from the area of Madrid. In order to obtain a fairly good idea of the HLA antigen frequencies in the Spanish population, our results have been compared with those reported from Barcelona. Haplotype frequencies were observed in 212 parents and compared with the frequencies estimated from the 491 individuals. The present data show certain characteristics of the Spanish population and are in good agreement with other studies in the demonstration of linkage disequilibrium between genes of the two series.

Direct activation of guinea pig macrophages by a B-cell mitogen.

Since polyclonal B-cell activators (PBA) require macrophages to induce modifications in the lymphocyte in vitro primary response to thymus-dependent antigens, we have investigated whether PBA act directly on macrophages. [14C]glucosamine uptake by guinea pig peritoneal adherent cells after stimulation with purified protein derivative (PPD), lipopolysaccharide (LPS), and dextran sulfate (DxS) was tested. PPD produced an increased [14C]glucosamine uptake, whereas LPS and DxS did not. According to our experiments, (a) PPD does not require the presence of lymphocytes to stimulate macrophages; furthermore, when lymphocytes were present in a concentration higher than 5%, a suppressor effect in the glucosamine uptake was found, and (b) there was no significant difference between the findings when peritoneal adherent cells were cultured in normal medium and in supernatant of lymphocyte cultures stimulated with PPD.

Lumphocytotoxins in leprosy.

Occurrence of cold lymphocytotoxins has been observed in 59 leprosy sera. In 46% of the patients, cold lymphocytotoxins were present whereas in helathy controls only 13% showed such antibodies. The highest incidence of alloantibodies was detected in lepromatous leprosy. Levels of autoantibodies, immunoglobulins and C3 were tested in parallel without finding any significnat correlations.