HLA polymorphism in a Mataco South American Indian tribe: serology of class I and II antigens. Molecular analysis of class II polymorphic variants.

In the present study, HLA-A, B, C, DR, DQ, and DP loci were analyzed in a group of Mataco Amerindians of Argentina. Using reagents from the 11th International Histocompatibility Workshop (11th IHW), class I specifities such as Bw70, Bw75, and Bw48 were found in this population, other than the HLA determinants commonly described in South American Indians. The class II antigens found were DR4, DRw14, and DRw8 at the DR locus, and DQw4 and DQw7 at the DQ locus. The analysis of DRB1-DR4 related alleles, performed by PCR amplification and oligonucleotide probe hybridization, showed the presence of DRB10403, 0404, 0405, and 0411 in individuals from this ethnic group. By the analysis of DRB1-DRw14 related alleles, two variants were found: DRB11402 and DRB11406, the latter provisionally called DRB1 14.6 in 11th IHW. The DRw8-related allele present was DRB10802. The analysis of DRB3 gene revealed only the presence of DRB30101 allele in DRw14 individuals. DPB1 locus was also analyzed in unrelated individuals of the same population. Only five DPB1 alleles were found: DPB1*0201, *0301, *0402, *0501, and *1301 over the 19 previously described in the literature. These findings emphasize the restricted HLA class I and II variation observed in this ethnic group as it has been previously shown in other American groups. Some particular haplotypes in this Mataco tribe are described in this work.