Epitopes of the HLA-A, B, C, DR, DQ and MICA antigens.

The intent for this chapter was to summarize the HLA epitopes that have been defined by adsorption and elution of antibodies from single HLA antigens to date. Examples of reactions of mAb and eluted allosera with the class I, class II and MICA SA are also presented. We have identified 103 HLA class I epitopes, of which 40 were defined by mAbs and 63 by alloantibodies mostly eluted from rHLA class I single antigen cell lines. We identified 32 epitopes shared by A-locus antigens, 43 epitopes shared by B-locus antigens, 4 epitopes shared by C-locus antigens, 16 inter-locus epitopes shared by A-B loci antigens, 5 inter-locus epitopes shared by B-C loci antigens and 3 inter-locus epitopes shared by A-B-C-locus antigens. Sixty HLA-DR epitopes have been defined, most by one aa residue on the HLA DR beta chain. However, as is the case with Class I epitopes, some DR epitopes are defined by one or more alternative residue(s). Eighteen HLA-DQ epitopes have been identified on the HLA-DQB chain and on the HLA-DQA chain of HLA-DQ antigens. Most DQ epitopes were defined by one aa residue. However, almost half are characterized by several alternative combinations of aa residues. Only a few DQA epitopes have been identified. Seven MICA epitopes have been defined to date. All are defined by a single aa residue.