Abstract
Summary A detailed analysis of conditions that prevailed within an in vitro system used for the study of the phagocytosis and adhesiveness of human polymorphonuclear neutrophilic granulocytes emphasized the critical role exerted by osmolality and hydrogen ion concentration on the test system. It was found that neither proteolytic enzyme antagonists such as epsilon amino caproic acid nor metabolic antagonists such as dinitrophenol interfered with leucocytic function when used in sub toxic concentrations. The membrane alteration responsible for phagocytosis and clumping has yet to be described although evidence suggests it to be enzymatically controlled.