EXPRESSION OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN-INDUCIBLE CYTOCHROME P4501A1 IN HUMAN SPLENIC LYMPHOCYTE-CULTURES

The induction of cytochrome P4501A1 (P4501A1) and P4501A1-specific 7-e thoxyresorufin O-deethylase (EROD) activity by 2,3,7,8-tetrachlorodibe nzo-p-dioxin (TCDD) was investigated in human splenic lymphocytes cult ures. EROD activity was induced by TCDD in mitogen (phytohemagglutinin and pokeweed mitogen) stimulated blast cells but not in the resting c ells. TCDD markedly induced EROD activity in a dose- and time-dependen t manner, The expression of P4501A1 mRNA was increased by TCDD in mito gen-stimulated cells as detected by Northern blot analysis, These find ings support the conclusion that TCDD induced the expression of P4501A 1 gene, resulting in increased EROD activity in mitogen-stimulated hum an splenic lymphocytes cultures.