Serum lysozyme activity in children with hematological and malignant disorders.

Pretreatment serum lysozyme activity was high in 2 children with myelomonocytic leukemia, 800 and 1 000 mug/ml, normal in all 10 cases of acute lyelocytic leukemia and subnormal in 21 of 34 cases of acute lymphocytic leukemia. Normal values were found in all but one case of acute lymphocytic leukemia during complete remission including 8 cases after all therapy had been discontinued. All 8 are still in complete remission. Low serum lysozyme activity was found in 5 patients with acute lymphocytic leukemia in complete relapse, this could possibly be helpful in the diagnosis of early relapse. Activity was subnormal in 5 of 17 children with malignant tumours, and in 3 of 65 cases of various benign hematological disorders.