The relationship of HLA-B and DR phenotypes to Behcet's syndrome, recurrent oral ulceration and the class of immune complexes.

A series of eighty Caucasian patients was divided into four groups with the mucocutaneous, arthritic, neurological and ocular types of Behcet's syndrome (BS) and a fifth group of patients with recurrent oral ulcers. The immunogenetic basis of the four types of BS was extended from HLA-B locus to the DR locus. Whereas B5 and more precisely the Bw51 split is the most discriminating marker of the ocular type of BS, DR7 also shows a significant increase in the ocular and neurological types. Indeed, most if not all patients with the ocular type have B5 and/or DR7. B12 and/or DR2 is significantly increased at the less severe end of the spectrum, the mucocutaneous and arthritic types. Patients with recurrent oral ulcers also show an increase in B12 and/or DR2. However, B12 and/or DR7 shows an increase in the relative risk in all four types of BS. These results suggest that HLA-B12, B5, DR7 and DR2 might in some way be associated with tissue localization of disease. Alternatively, since patients with HLA-B12 show a significantly greater ratio of IgG:IgA circulating immune complexes than those with B5/DR7/DR2, tissue localization might be influenced by the immune complex isotype. A significant relationship was also found between the MT2 and MT3 B cell alloantigen system and BS, with particular reference to MT2 and the neurological type and MT3 and the ocular type of BS.