HLA-D typing in multiple sclerosis: Israelis tested with European homozygous typing cells.

The association of A3, B7, Dw2 and DR2 histocompatibility (HLA) markers with multiple sclerosis (MS) is well established among Northern Europeans and Caucasoids in the United States. We showed previously that A3 and B7 were not increased among Israelis with MS, and in a preliminary study Dw2 as well. An association of A3 and B7 is also lacking in Italians, Jordanian and Japanese MS patients. In Black American MS patients, the B7 frequency is slightly increased but Dw2 is still significantly associated with MS. For the HLA-DR antigen series DR2 is shown to have a stronger association to MS than A3 and B7. Conceivably, this antigen could be associated with MS even in populations where an association with A3 or B7 is lacking. Therefore, a study of HLA-A, B, C, DR and D antigens was carried out in Israel. No significant excess or deficiency of HLA antigens was found in MS. Possible explanations for these results are as follows: (1) the relevant HLA-D alleles in the Jewish population were not detected by the homozygous typing cells (HTCs) used, since they were derived primarily from European sources; (2) in contrast to the Caucasoid populations the genetic factor predisposing for MS is not associated with HLA alleles in the Israeli population; (3) MS is an heterogeneous disease and in Israelis, an environmental factor is sufficient to cause the disease.