Low constitutive activity of aryl hydrocarbon hydroxylase in phytohaemoagglutinin-stimulated peripheral blood mononuclear cells of children after treatment for acute lymphoblastic leukemia.

In six children in the first remission after treatment of acute lymphoblastic leukemia (ALL) the constitutive activity of aryl hydrocarbon (benzo-[alpha]pyrene) hydroxylase (AHH) (0.14 +/- 0.04 U, i.e. pmol of 3-OH-benzo[alpha] pyrene x 10(-6) cells x min-1) in phytohaemoagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) was significantly lower (P 0.05) than the constitutive activities in the parents of the children (0.25 +/- 0.09 U) and in the control adult group (0.26 +/- 0.09 U). In methylcholanthrene (MC)-induced activities of AHH no significant differences were observed between the above groups.