LYSOZYME IN HUMAN NEUTROPHILS AND PLASMA - A PARAMETER OF MYELOPOIETIC ACTIVITY

Lysozyme was found to be present in all three types of human neutrophi l granules (azurophil-, specific- and gelatinase granules) as determin ed by subcellular fractionation, employing a three-layer Percoll gradi ent and measurement of lysozyme by a novel ELISA. The content of lysoz yme was also measured in plasma. In contrast to other neutrophil granu le proteins (lactoferrin, NGAL, and gelatinase), plasma lysozyme was u naffected by increase in the number of circulating neutrophils induced by intravenous administration of methylprednisolone to healthy indivi duals. Also in contrast to lactoferrin, NGAL, and gelatinase, plasma l ysozyme was found to rise 1 week prior to detectable increases in the number of circulating neutrophils in patients undergoing allogeneic bo ne marrow transplantation. We conclude that plasma lysozyme is a param eter of myelopoietic activity and may be useful as a marker for bone m arrow repopulation after transplantation.