IMMUNOSUPPRESSIOM AND SERIOUS INFECTIONS DURING MAINTENANCE CHEMOTHERAPY OF ACUTE LYMPHOBLASTIC LEUKAEMIA IN CHILDHOOD

58 patients with ALL were studied at intervals during two years of maintenance chemotherapy. All patients received the same induction and cranial irradiation and were then randomized into two groups. Group C (Continuous) received daily drugs and Group I tIntermittent) were given drugs for five days followed by 16 days without drugs in successive cycles. Patients in both groups received the same total drug dose. Blood neutrophils counts were lower in Group I and fell after each course of drugs whereas neutrophil counts remained relatively constant in Group C. Lymphocyte counts, PHA responsiveness and serum immunoglobulin levels were significantly lower in Group C compared with Group I at all times tested during the study. The incidence of serious infections was higher in Group C (11/34 patients) than in Group I (4/24 patients). In most cases the onset of infection was preceded by a period of extreme lymphopenia (<0.4×109/1). Intermittent chemotherapy is therefore less suppressive of lymphocyte population size and function than continuous chemotherapy.