Biological and clinical significance of the HLA system

Abstract

The HLA associations reported so far have implication in diagnosis prognosis and prophylaxis for a few of the diseases and in several cases, they have helped to clarify disease heterogenicity. However ' the area where a full consensus is yet to be achieved is regarding the mechanism by which these disease associations with HLA antigens work. Numerous investigators have discussed various possible mechanisms in the light of individual diseases. In general diseases associated with HLA class I antigens may in some way involve cytotoxic T lymphocytes whereas those more strongly associated with HIA - class II antigens (-DR) may involve T helper or suppressor lymphocytes. With the availability of new genetic methodology, significant advances in our understanding of the inheritance pattern of some diseases have been made. Studies of the newly discovered HLA polymorphisms, such as the DQ and DP markers at the- cellular level (Class - 11 genes products) and restriction sites at the DNA level are likely to lead to new associations. Further, the discovery of the monoclonal antibodies recognizing distinct epitopes on HLA class - 11 molecules and DNA probes recognizing DNA flanking sequences would help greatly in providing much stronger genetic marker systems in these diseases.