Development of anti-asparaginase antibodies in childhood acute lymphoblastic leukemia.

L-asparaginase is a basic agent of antileukemic therapy, but allergic reactions against the drug and the development of anti-asparaginase antibodies are significant side-effects. The aim of our study was to estimate the presence of anti-asparaginase antibodies and to correlate the results with clinically apparent allergic reactions and with L-asparaginase activity during the treatment. We examined 13 children with newly diagnosed acute lymphoblastic leukemia (ALL), treated according to the Polish Pediatric Leukemia/Lymphoma Group protocol, based on ALL-BFM 95. Enzyme activity was estimated in serum samples, collected before each L-asparaginase administration, using the photometrical method. Anti-asparaginase antibody concentration was measured by enzyme-linked immunosorbent assay (ELISA) at the two time points: at the last day of L-asparaginase treatment in the induction and the reinduction phase. The mean L-asparaginase activity was 273 IU/L in the induction phase; no anti-asparaginase antibodies in this phase of treatment were found. The mean L-asparaginase activity was 425 IU/L in the reinduction phase of treatment; in five children anti-asparaginase antibodies were detected. In four of these five children low L-asparaginase activity and/or allergic reactions against L-asparaginase were noted. Our observations suggest a correlation between the presence of anti-asparaginase antibodies and L-asparaginase activity in childhood ALL.