Six functionally HLA-D homozygous typing cells were identified by a restricted investigation into the Hungarian inbred population of Ivád. These putative HLA-D homozygous typing cells were then tested against a highly selected Scandinavian population sample of 60 individuals previously typed by histocompatibility reference reagents. The different HLA-D specificities could thus be identified: one closely matching HLA-Dw5, another resembling the Oslo LDoH specificity, while the last seems to be unique. Only one of the typing cells thus ascertained were HLA-B homozygous and were selected on the basis of the Ivád family structure and not on the basis of serological HLA typing.

A Hungarian random population sample was tested for six well-known and two new HLA--D specificities. HLA--D antigen and gene frequencies in the studied population agree with the frequencies observed in pooled random Caucasians, only HLA--Dw3 being significantly elevated. The incidences of Dw1 and Dw4 are, however, lower while the incidences of the Dw5 and Dw6 alleles seem to be higher in our population sample without reaching statistical significance. As for the two new specificities, the IVAD-1 specificity has a low frequency, while IVAD-3 occurs quite frequently. HLA--B and HLA--D associations seem to be different in our population sample as compared to others. In spite of the high incidence of the HLA--Bw35 antigen, no HLA--D association was found. The two new HLA--D specificities did not show association with any of the established HLA--B antigens.