Immunosuppressive effects of 2‐acetyl‐4‐tetrahydroxybutyl imidazole (THI) in the rat

Abstract

THI is a component of ammonia caramel, a widely used food colouring. The effect of THI on the immune system has been determined in the male F344 rat. THI was given in the drinking water at doses of 1, 10 and 50 mg// (equivalent to 01, 1 and 5 mg/kg per day) to animals on a vitamin B6‐deficient diet. After 1 week, the immune competence of the animals was assessed under continued THI treatment. No marked changes in thymus or spleen weight were observed after THI treatment, although there was an increased number of pyknotic cells in the thymic cortex, mainly engulfed by macrophages and there appeared to be a slight thinning of the cortex area. THI produced a significant loss in T and B lymphocytes in peripheral blood but not in the spleen. No change in natural killer