Oligonucleotide typing is a perfect tool to identify antigens stimulatory in the mixed lymphocyte culture.

An important criterion for the selection of donors for bone marrow transplantation is the grade of matching for HLA between donor and recipient. For patients that lack an HLA-identical sibling, an extending pool of unrelated volunteers for bone marrow donation is available. From these donors the best matched candidate can be selected by serological typing, followed by a mixed lymphocyte culture (MLC). Oligonucleotide genotyping for HLA class II antigens is considered to be valuable for the prediction of MLC reactivity. We investigated whether this typing method, in combination with serological typing, would cover the recognition of all MLC stimulatory determinants. One hundred thirty-six combinations of HLA-A, -B, and -DR serologically identical individuals were tested in the MLC. Additional typing for HLA-DRB and HLA-DPB by oligonucleotide genotyping made it possible to evaluate the influence of these genes on MLC reactivity. Combinations that were matched for HLA-DRB gave significantly lower responses than those that were mismatched. Nevertheless, in the matched combinations responses were observed to 94% relative response index. These responses could all be attributed to HLA-DP, since all combinations that were identical by HLA-DPB genotyping were negative in the MLC. In conclusion, with the combined use of serology and oligonucleotide genotyping, responder-stimulator combinations can be selected that are identical for all MLC stimulatory determinants.