Monoclonal antibodies to polymorphic epitopes on Ia antigens: three independent groups of determinants expressed on DRw6 homozygous cells.

Murine monoclonal antibodies directed against polymorphic epitopes on HLA-linked antigens were readily obtained following a single immunization with DRw6-homozygous cells. Five antibodies directed against class II antigens were isolated. Two precipitated DC-like molecules and 3 DR-like molecules from the immunizing lymphoblastoid cell line. Analysis of association with HLA-DR antigens in a panel of 60 individuals revealed 2 antibodies directed against the DC1 specificity (S1, R1) and one against the MT2 specificity (R3). Antibodies S2 and S3 showed significant association with DRw6 (chi 2 = 30.27) and DRw6 and w8 (chi 2 = 18.86), respectively. An analysis of 29 haplotypes indicated that epitopes defined by these monoclonal antibodies appear to identify polymorphic determinants on three independent gene products which can be encoded by a single HLA haplotype.