Neutrophil defect in multiple myeloma. Studies on intraneutrophilic lysozyme in multiple myeloma and malignant lymphoma.

Intracellular lysozyme concentration was measured in neutrophilic granulocytes from 25 patients with multiple myeloma. At diagnosis intraneutrophil lysozyme activity was significantly reduced (mean reduction 50%). During clinical remission after 1–4 months of intensive chemotherapy values were normalized. In 18 cases studied at various stages of the disease from 6 to 70 months after diagnosis there was a significant negative correlation between the duration of the disease and neutrophil lysozyme concentration. The decrease in neutrophil lysozyme concentration was significantly correlated to clinical disease activity and the percentage of plasma cells in bone marrow aspirates, whereas there was no correlation between the concentration of M-protein in serum and the neutrophil lysozyme concentration. Plasma lysozyme concentration was normal. In contrast, neutrophil lysozyme concentration was normal in 18 patients with stage III-IV malignant lymphoma. Plasma lysozyme in this group was significantly higher than normal. The difference in neutrophil lysozyme patterns between multiple myeloma and malignant lymphoma supports the hypothesis that the defect in neutrophil maturation seen in malignant blood disorders is directly related to the infiltration of the bone marrow by pathologic cells.