The characteristics of the HLA antigens determined by cellular techniques.

The complexity of the D region of the HLA complex is rather great. Three loci--HLA-DP, DQ, DR are very well established in this time. However, the question about the independence of the first known locus of this region--HLA-D--remains elusive--it is still not known if HLA-D antigens are really independent or they rather represent some epitopes of HLA-DR/DQ antigens. The HLA-DP antigens represent the additional series of specificities of the HLA complex recognized by PLT technique. On the other hand HLA-PL antigens, detected by PLT too, correlate as to HLA-D as to HLA-DR antigens and with a great probability they do not form an independent group of HLA antigens.