Lysozyme Activity in Human Neutrophilic Granulocytes

S ummary . Among five different methods for the extraction of lysozyme from human neutrophilic granulocytes (mechanical disruption, freezing‐thawing, sonication, solubilization with saponin and with n ‐butanol), extraction with n ‐butanol was found to give the highest lysozyme yield per cell. With this method the lysozyme content of neutrophilic granulocytes was measured in a control group with no haematological, renal or infectious disease, and in patients with bacterial infection, severe uraemia, and myeloproliferative disorders. It was found that the lysozyme concentration in normal human adults was 2.7 μg per 10 6 neutrophils. Intraneutrophilic lysozyme in patients with bacterial infection was reduced by 50% whereas the activity in patients with severe uraemia was reduced by 25%. The content in patients with myeloproliferative disorders was normal. The intraneutrophilic lysozyme content varied inversely with the severity of the infection as judged by the degree of neutrophil leucocytosis. Taking all patients examined, the intraneutrophilic lysozyme activity varied inversely with the degree of toxic granulation. A negative correlation was also demonstrated between neutrophilic lysozyme and the serum creatinine level. It is suggested that bacterial infection and uraemia suppress lysozyme synthesis in the bone marrow, although other mechanisms cannot be excluded. The consequences for neutrophil function are unknown.