Inhibitory effects of carcinogenic tryptophan pyrolysis products on phytohemagglutinin-induced blast transformation of human lymphocytes

Abstract

In order to evaluate the effect of carcinogenic heterocyclic amines on the stimulus-reaction system of human cells, we examined the effect of 5 kinds of carcinogenic heterocyclic amines including 2-amino-3-methylimidazo [4,5- f]quinoline (IQ), 2-amino-6-methyldipyrido[1,2- a3',2'- d)imidazole (Glu-P-1), 2-amino-dipyrido[1,2- a:3',2'-( d]imidazole (Glu-P-2), 3-amino-1,4-dimethyl-5 H-pyrido[4,3- b]indole (Trp-P-1) and 3-amino-1-methyl-5 H-pyrido[4,3- b] indole (Trp-P-2) on human lymphocyte (4 × 10 5 cells/ml) blast transformation induced by 0.125% phytohemagglutinin (PHA). Both Trp-P-1 and Trp-P-2 exhibited an inhibitory effect on the lymphocyte proliferation stimulated by PHA at the final concentration of 1.0–5.0 and 1.0–10 μM, respectively. The concentrations of Trp-P-1 and Trp-P-2 causing 50% inhibition were 3.1 and 5.1 μM, respectively. However, the other carcinogenic heterocyclic amines examined did not show any inhibitory effect on lymphocyte mitogenesis even at a final concentration of 10 μM. Viabilities of lymphocytes were more than 90% ( n = 3 × 5) when 5 kinds of carcinogenic heterocyclic amines (0.1 ml) were respectively added at the final concentration of 10 μM to the lymphocyte culture medium (4 × 10 5 cells/0.9 ml).