Abstract

In order to examine macrophages phagocytosing polymorphonuclear leucocytes (PMNs) in detail, we established a new method, whereby a large number of PMN-phagocytosing macrophages (PPMs) were easily induced. PPMs were harvested from the peritoneal cavity after thioglycollate medium, oyster glycogen, phytohaemagglutinin (PHA), L. monocytogenes or S. aureus had been injected i.p. into guinea-pigs. When thioglycollate medium or oyster glycogen was injected i.p., the number of the PPM reached a peak 48 h later and PPM formed 20% or more of total macrophages. When L. monocytogenes or S. aureus was injected i.p., the ratio of PPM to total macrophages reached a peak 24 h later. Morphologically, some of the phagocytosed PMNs were not degenerated and the others were at various stages of degeneration. The ability of macrophages to phagocytose PMNs was suppressed when 10(-6) mol/kg of colchicine was administered i.p. 1 day after the injection of the irritants.

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