Eosinophils chemotactic factor (ECF). IV. Inhibitory activity in human peripheral leukocytes.

A low molecular weight eosinophil chemotactic factor (ECF) can be released from human peripheral polymorphonuclear leukocytes by phagocytosis, by reverse anaphylaxis or by the calcium ionophore A 23187. During later phases of ECF-release, a leukocyte-derived ECF inhibitor (LDI) is concomitantly released. Inhibitory activity is also present in sonicates of unstimulated cells, suggesting that the factor is preformed. On chromatographic analysis of neutrophil (PMN) sonicates, two peaks of inhibitory activity at greater than 200,000 and at about 80,000 daltons each are eluted. With preparations containing lymphocytes, monocytes and basophils (L/M/B), only peak (greater than 200,000 daltons) is apparent. The LDI is heat stabile (56 degrees C, 1 h), affects only the ECF and not the migrating eosinophils, and does not inactive bacterial factor or deactivate neutrophils. Evidence is presented suggesting that the mode is by binding of ECF rather than by enzymatic destruction.