Serum lysozyme activity in children with acute leukemia.

Serum lysozyme activity was measured in samples from children with acute leukemia, malignant tumours, and in normal children. All children with acute lymphatic leukemia (ALL) had significantly reduced levels of lysozyme at diagnosis, and none of the children fell within the normal range. Children with ALL in complete remission had lysozyme levels comparable to normal chidren, while children with ALL in relapse also had pathological low levels. Children with ALL in remission and off therapy also had normal levels of lysozyme. Children with acute myelogenous leukemia had normal lysozyme levels, while children with monomyelocytic leukemia had substantially elevated lysozyme levels before treatment. Determination of serum lysozyme activity in children with acute leukemia is of value both for diagnosis and for evaluating the effect of therapy.