IDENTIFICATION OF HLA-DRB1 AND HLA-DQB1 IDENTICAL INDIVIDUALS BY A CYTOKINE-BASED MIXED LYMPHOCYTE CULTURE

Cytokine determination in MLC is under discussion as providing more se nsitive and specific information regarding host-graft compatibility, a nd is therefore suggested to represent a new method for transplantatio n medicine. Little is known, however, about the stimulatory influence of HLA class II antigens and minor lymphocyte-stimulating antigens (Ml s). Our results demonstrate that cytokine determination in MLC is suit able to detect identical alleles of HLA-DRB1 and HLA-DQB1. Among more than 100 random MLC experiments, we observed one cytokine pattern simi lar to the cytokine release detected in a control MLC of HLA-identical siblings, which showed marginal or no secretion of IL-2, sIL-2R, IFN- gamma, TNF-alpha, and IL-6. HLA-typing of these two nonreactive indivi duals elevated identical HLA-DRB1 and HLA-DQB1 regions, while they dif fered in the HLA-DP locus. This suggests that HLA-DP has no stimulator y influence on cytokine release. Further investigation of the stimulat ory capacity of HLA-DR and DQ showed that HLA-DR is more effective in inducing IFN-gamma release than HLA-DQ. To evaluate the stimulatory in fluence of human Mls, i.e., human endogenous retroviruses (HERV), we a nalyzed HERV sequences of nonreactive individuals. Both individuals sh owed identical HERV patterns. A third individual, who had shown distin ct cytokine release in MLC with both nonreactive individuals, differed in the HERV fragments. In conclusion, cytokine determination in MLC i s a new method of evaluating the biological relevance of stimulatory a ntigens after allogeneic stimulation detecting all individual diversit ies in one experiment.