Serum beta2 microglobulin in recurrent aphthous stomatitis and Behcet's syndrome

β2Microglobulin (β2m), a constituent of cell surface histocompatibility antigens, was measured in scrum from twenty‐eight patients with recurrent aphthous stomatitis, twenty‐four patients with Behçet's syndrome and twenty‐eight matched controls. Serum β2m concentrations were significantly greater in recurrent aphthous stomatitis and in Behçet's syndrome than controls, but failed to differentiate the two diseases.