Abstract

The in vivo effect of various cytotoxic drugs and cranial irradiation on neutrophil chemotaxis was tested in 62 children with acute lymphoblastic leukaemia and in 10 patients with other malignant disease. Cranial radiotherapy had a transient adverse effect on neutrophil chemotaxis after completion of the course which was most marked in children. Methotrexate (MTX) and 6-mercaptopurine (6-MP) alone and in combination had a variable effect of chemotaxis, which was most marked nine days after the end of the course. The effect of 6-MP was clearly dose-related, but continuous therapy (75 mg/m2 day) had the greatest inhibitory effect of all the regimens tested. The in vitro effect was studied in 48 leukaemics and in 85 controls (adults and children); all the patients with leukaemia had been off treatment for at least six months. No difference was found between the effects of drugs tested on control or leukaemic cells. The greatest inhibitory effect was found in vinblastine, adriamycin, 6-MP, and vincristine, all of which were closely dose-dependent, MTX, prednisolone, and asparaginase had no effect on chemotaxis when tested in this way.