The immunosuppressive effects of long-term combination chemotherapy in children with acute leukemia in remission.

The immunosuppressive effects of maintenance combination chemotherapy given for periods ranging from 8 to 28 months to 20 children with acute lymphocytic leukemia in remission were investigated. There was depression of both the primary antibody production to the hemagglutinin antigen of the Hong Kong influenza virus and the anamnestic response to the neuraminidase of the same virus. The primary response (hemagglutination inhibition) was affected to a greater extent than the secondary (neuraminidase inhibition) response. A preferential depression of 2-mercaptoethanol-resistant hemagglutination inhibition antibodies (IgG) was also observed. One-fourth of all acute lymphocytic leukemia patients had low serum IgG levels. In vitro transformation of lymphocytes was a poor index of immunocompetence. After 2 years of continuous chemotherapy, children with low IgG and suppressed antibody production had normal response to phytohemagglutinin. This initial study on the immunocompetence of patients with leukemia undergoing long-term combination chemotherapy should provide a base line to establish correlations between immunological parameters and infectious complications.