An almost complete and bidirectional association exists between HLA-Cw
17 and the HLA-B antigens B41 and B42. Serological and molecular anal
ysis of an individual in which HLA-B4101 was identified in the absenc
e of Cw17 provides experimental evidence to prove a previously propos
ed hypothesis predicting that alloantisera classified as ''B41-B42'' a
re instead specific reagents for HLA-Cw17.