Immunosuppression and Serious Infections in Children with Acute Lymphoblastic Leukaemia:a Comparison of Three Chemotherapy Regimes

Abstract

Children (84) presenting with acute lymphoblastic leukemia were entered into a trial designed to test the effect on host toxicity of regular drug-free periods during chemotherapy. Patients received the same total dose of drugs continuously (daily), intermittently (a 5 day course every 3 wk) or in an intermediate way between these 2 (a 14 day course followed by a 7 day gap). Mean neutrophil counts were lower in the intermittent group and fell significantly at 6 wk intervals, after courses which included prednisolone and vincristine in addition to methotrexate and 6-mercaptopurine. Mean lymphocyte counts, mitotic response to phytohemagglutinin and plasma immunoglobulin levels were significantly lower in the continuous group. The results in the intermediate group fell between those of the other 2 groups. All 6 remission deaths occurred in the 42 patients in the continuous group, who had a much higher incidence of infections (mostly viral and protozoal) than the other 2 groups. The intermittent chemotherapy schedule permits maintenance of a lymphocyte population size and function which provides a satisfactory level of defense against infection without prejudice to its anti-leukemic effect.