ALLELIC HETEROGENEITY OF HLA-B35 SUBTYPES IN DIFFERENT POPULATIONS ASASSESSED BY DNA TYPING

HLA-B35, a class I antigen differentially associated to several diseas es in different ethnic groups, comprises at least eight alleles which differ among them by one to six amino acids. In the present work a rap id DNA typing procedure was used to investigate the distribution of th e various HLA-B35 alleles in different populations. The approach is ba sed on a group-specific PCR amplification of a set of closely related HLA-B alleles sharing a Thr in position 45 of the alpha-1 domain. The amplified DNA was then hybridized to a panel of sequence-specific olig onucleotide (SSO) probes designed to recognize the polymorphic residue s in previously reported HLA-B35 subtypes. This methodology was succes sfully tested in 100 individuals of four different populations, previo usly typed by serology as HLA-B35, and in six reference panel cells of the 10th International Histocompatibility Workshop. HLA-B3501 was th e predominant subtype in all populations. B3502, B*3503 and, to a les ser extent B3508, were also found. Among Mexican Mestizos, thirteen i ndividuals had patterns of SSO hybridization suggestive of new B35 all eles. The evolutionary considerations on the different B35 alleles and their extended B35,Cw4 haplotypes are discussed.