Can therapeutic considerations provide clues to the etiology of aphthous stomatitis and Behçet's syndrome?

An attempt is made to derive clues as to the etiology of aphthous stomatitis and Behçet's syndrome from analysis of the mode of action of the various therapeutic agents which have been employed in these diseases. It is concluded that owing to the diverse and frequently contrasting modes of action of these agents, this may well be an unproductive task. There is one exception to this conclusion. Since levamisole in small concentrations given intermittently appears to act as an immunopotentiator, and in large, prolonged dosages possible as an immunosuppressor, future "diagnostic-therapeutic" trials could examine this dichotomy to determine whether aphthous stomatitis and Behçet's syndrome are infectious or hypersensitivity diseases.