Novel neutrophil chemotactic factor derived from human peripheral blood mononuclear leucocytes

Human mononuclear leucocytes isolated from the peripheral blood by centrifugation on Ficoll-Hypaque cushions and adherent on plastic petri dishes, produced a chemotactic factor that attracted human neutrophilic granulocytes to the same extent as did optimal concentrations of the complement split product C5a and the leukotriene B4. The active component eluted from a Sephadex G-50 gel filtration column as a single peak with an apparent molecular weight of 10,000. The chemotactic activity was resistant to reductive cleavage of disulfide bonds and heating at 100 degrees C for 30 min but was lost when reduction and heating were combined. Digestion with a proteolytic enzyme eliminated the attractive potential. The data suggest that this is a novel chemotactic peptide. It is conceivable that it has been seen previously and was mistaken for a lymphokine or interleukin 1.