Immunogenetic markers and immune response in patients with recurrent oral ulceration.

20 patients, aged 20 to 72 years (mean 36.5 years), 14 with recurrent (RAS) and 6 with recurrent cicatrizing (RCAS) aphthous stomatitis were studied. 3 patients (15%) had the HLA locus A11 antigen, whose frequency in the Finnish population is 8%. 5 patients (25%) had B12, which occurs in 15% of the normal population. Results of routine serological tests were normal. All had normal serum levels of IgG, IgM, IgA and complements C3 and C4. 4 patients, 2 with RAS and 2 with RCAS, had raised serum IgE. Precipitating antibodies against milk protein were detected in 2 patients and against gluten in 1. In 4 patients, tests for immediate allergy were positive. 5 patients had antibodies to double-stranded DNA. Delayed hypersensitivity reactions were normal, and the PHA stimulation of lymphocytes elicited normal T-cell responses in all patients except one with RCAS. In this patient, there was a striking parallelism between an increase in PHA-reactive lymphocytes and clinical improvement. The serum of this patient contained a binder for 125I-labelled PHA, a binder not consistently detected in the other patients with ROU. Lymphocyte dysfunction may play a rôle in ROU. Of the 16 biopsy specimens of aphthous tissue studied by direct immunofluorescence for IgG, IgM, IgA, fibrinogen and C3, 15 specimens contained deposits of C3 in and along mucosal vessels, whereas among the 15 controls only 1 specimen of erosive lichen planus showed deposits of C3 along capillary walls. Immune complexes precipitating in capillary walls appear to be a common feature of ROU.