Acute phase proteins and C9 in patients with Behcet's syndrome and aphthous ulcers.

Estimation of the concentration of C9, C-reactive protein (CRP) and alpha1-antitrypsin in forty sera from patients with Behcet's syndrome and recurrent oral ulcers showed significantly increased amounts of C9 and CRP in Behcet's syndrome. The concentration of C9 was also significantly raised in recurrent oral ulceration, though to a lesser extent than in Behcet's syndrome. The assay C9 and CRP might be useful in the differential diagnosis of Behcet's syndrome, especially from recurrent oral ulcers. It is suggested that during epithelial inflammation in recurrent oral ulcers some of the acute phase proteins are increased and in some patients these may modulate the immunological mechanism in such a way as to induce a transition from focal oral ulceration to the multifocal Behcet's syndrome.