THE HLA POLYMORPHISM OF 2 DISTINCTIVE SOUTH-AMERICAN INDIAN TRIBES - THE KAINGANG AND THE GUARANI

The HLA-A, B, C, DR and DQ antigens of 240 Kaingang and 98 Guarani ind ividuals have been characterized. The most frequent antigens found amo ng the Kaingang are A31, 2, 24; B35, 51, 39, 48; Cw4, 7, 3, 1; DR8, 4, 2; DQ blank, 3. In the Guarani, they are A2, 28, 31; B40, 62, ''53G'' ; Cw3, 4; DR2, 4, 8, 6; DQ3, blank. B''53G'' is an unusual antigen of the B5 cross-reactive group. DQ blank possibly corresponds to DQ4, not tested in this study. The reaction patterns of B35, B40 and DR4 indic ate intra-tribal (of B35 and B40), and inter-tribal (DR4, B40 and B35) heterogeneity of these antigens. 408 Kaingang and 141 Guarani haploty pes were defined by segregation analysis. Of the commonest 10 Guarani and 9 Kaingang haplotypes, only one is shared by both tribes. Signific ant, positive linkage disequilibrium values for HLA-A,B; HLA-A,C; HLA- B,DR and most HLA-B,C antigen pairs were also different for the two po pulations. Genetic distance estimates between these two and another se ven South-American Indian populations, and relative to the major human races (negroids, caucasoids, and mongoloids) reveal a comparatively h igh degree of divergence between the Kaingang and the Guarani, which i s uncommon for Amerindian populations living close one to another.