HL-A histocompatibility antigens in recurrent aphthous ulceration.

The frequency of HL-A phenotypes has been investigated in 64 patients who had recurrent aphthous ulcers and 100 subjects who did not. The HL-A phenotypes were determined by a two-step microcytotoxicity test on peripheral blood lymphocytes, incubating these cells with a range of defined antiserums and complement and subsequently assessing lymphocyte viability by dye exclusion. There were no significant differences between the frequency of individual HL-A antigens in the patients with aphthous ulceration and those of subjects without aphthous ulceration. Similarly, no differences in numbers of shared antigens could be demonstrated. The distribution of HL-A antigens was essentially similar in subdivisions of patients with aphthous ulceration, grouped on the basis of sex, family history, age at onset, and maximum number of concurrent ulcers and their duration before healing.