Diminished release of lactoferrin from polymorphonuclear leukocytes of human neonates.

In neonatal and adult polymorphonuclear leukocytes (PMN) we determined the content and the release of beta-glucuronidase, myeloperoxidase, lysozyme and lactoferrin. We found an equal total content of these proteins in adult and neonatal PMN, except for a lower lysozyme concentration in neonatal PMN. In the presence of opsonized zymosan myeloperoxidase, lysozyme and beta-glucuronidase were released in equal amounts; lactoferrin, however, was released to a lower rate from neonatal than from adult PMN (p less than 0.0005).