Impaired lymphocyte stimulation by some streptococcal antigens in patients with recurrent aphthous stomatitis and rheumatic heart disease.

The effects of pathogenic and non-pathogenic streptococci, streptococcal cell wall products, and phytohaemagglutinin on human peripheral leucocyte cultures from four groups were studied. These groups were: (1) normals, (2) patients with aphthous stomatitis, (3) patients with Behçet's and (4) patients with rheumatic heart disease. The degree of lymphocyte stimulation by these materials was measured by uptake of [H]thymidine into DNA . In normals, patients with aphthous stomatitis, and Behçet's disease, the human pathogenic group A streptococci produced significantly greater stimulation of DNA synthesis than did the less pathogenic non-haemolytic streptococci. Lymphocytes from patients with aphthous stomatitis showed significantly less stimulation of DNA synthesis than comparable normal controls when exposed to heat-killed Streptococcal 2A, organisms which have been implicated in the disease. Human pathogenic strains of group A streptococci which have been implicated in rheumatic heart disease stimulated significantly less proliferation of lymphocytes from patients with rheumatic heart disease than of those from a comparable group of normal controls. This hypo-responsiveness persisted when the patients' lymphocytes were cultured in normal human serum. The chronically ill Behçet's patients' lymphocytes did not differ significantly from normal. These observations indicate a deficiency of the cellular response of certain patients to antigens from organisms thought to be aetiologically related to their disease.