HLA--D typing with homozygous cells identified in an American indigenous isolate. I. Population studies.

Lymphocytes from six individuals homozygous for their HLA--A, --B, --C and --D loci belonging to an American indigenous group, the Warao, have been used as typing cells to detect HLA--D determinants in 121 donors from the same indigenous isolate and in 71 donors of mixed ethnic origin living in Venezuela. Two determinants responsible for strong proliferation in mixed lymphocyte cultures have thus been identified. Four HLA--A2, B5 cells (r values between 0l72 and 0.57) identify a determinant provisionally called LD5a showing a gene frequency of 0.30 among the Warao and of 0.09 among the population of mixed ethnic origin. The nearest B locus antigen to this new specificity among the Warao is HLA--B5 (r value = 0.20). A second determinant identified by two HLA--A2, B15 sisters (r values of 0.71) shows a gene frequency of 0.15 among the Warao and of 0.03 among the mixed population. The latter is related to Dw8 as shown by results of the VI and VII Histocompatibility Workshops, and is weakly associated (r value of 0.28) to HLA--B15 among the American indigenous population tested.