[Immunosuppressive effect and promotor activity for hepatic carcinogenesis of thiobenzamide].

Thiobenzamide (TB) administration to rats (1 g/Kg of diet for 4 weeks) 10 days after a single i.p. injection of dimethylnitrosamine promotes the growth of preneoplastic liver lesions as evidenced by the sharp increase in number and area of gamma-glutamyltranspeptidase-positive hepatocellular foci. At the same time the number of the plaque forming cells isolated from the spleen of rats challenged with sheep red blood cell after the completion of a TB cycle is significantly lower than in the controls 5 as well 13 days after immunization. Accordingly, TB could act as immunodepressant in the rat; this should be taken into account as far as the promoting ability of such xenobiotic is concerned.