To determine the prevalence, duration, and a potential cause of humoral defect(s) in children with acute lymphoblastic leukemia (ALL) at least 1 year after completion of chemotherapy.

Antibody titers for mumps, rubeola, rubella, tetanus and diptheria toxoid, poliovirus serotypes 1, 2,and 3, Haemophilus influenzae type b, varicella, and hepatitis B were obtained from 100 children with ALL. Children with non-protective titers to these microbial antigens were re-vaccinated and re-studied after anamnestic vaccine challenge.

The percent of children with ALL who had protective titers was markedly less than that anticipated for immunized control subjects. Longitudinally, many titers fluctuate between protective and non-protective antibody responses after re-immunization. The chemotherapy protocol used did not affect the ability of these children to express protective antibody responses. T-, B-, and NK-cell numbers and proliferative responses to mitogens were all normal. Age correlated with titer results for certain vaccines.

Children in remission from ALL have a high prevalence of humoral immune defects that are not related to any specific chemotherapy regimen. This antibody deficiency may place children with ALL at risk for the development of these bacterial and viral diseases, even after completion of chemotherapy. Pediatricians, oncologists, or both should periodically monitor humoral immunity after chemotherapy and re-vaccinate these children, as needed, to ensure prolonged immunoprotection.