The impact of the HLA-system in clinical medicine

A short overview of the genetics of HLA is given. The most remarkable point of the present day situation is that when we use HLA in the clinic we not only ignore much of the immunogenetic information which is available, but that on top of that we are still ignorant of a large number of genes in the HLA super-region and of their functions. When reviewing the biology of HLA it becomes clear that evidence can be found which supports the notion that the polymorphism might protect the human race against eradication by epidemics or endemics. The molecular basis of the recognition of viral, bacterial or other allogeneic antigens is briefly and schematically summarized. The clinical importance of HLA s.s. is two-sided. The first and at the moment in the clinic the most important contribution is matching for HLA in platelet transfusion, bone marrow transplantation and organ transplantation. The other reflects on the capacity of allogeneic HLA antigens, whether given as blood transfusion or through exposure of the newborn infant to maternal cells to influence the T and B cell repertoire. Preliminary evidence is reviewed indicating that this might not only be of importance in organ transplantation but also in disease predisposition.