Inhibitory Effect of SV-IV, a Major Protein Secreted From the Rat Seminal Vesicle Epithelium, on Phagocytosis and Chemotaxis of Human Polymorphonuclear Leukocytes

Abstract

The effect of SV-IV, one of the major proteins secreted from the rat seminal vesicle epithelium, on phagocytosis and chemotaxis of human polymorphonuclear leukocytes (PMNs) has been studied. Various cytological, biochemical, metabolic, and physical correlates of both biological activities have been found to be markedly reduced by the presence in the medium of micromolar concentrations of protein SV-IV. Moreover, the Scatchard analysis of the labeled SV-IV binding to PMN cell surface has demonstrated that such binding is specific. The binding sites contain only saturable components, completely displaceable by unlabeled SV-IV. The number of the specific sites has been calculated to be 87,000/cell, with a Kd of 1.72 X 10(-7) M. The molecular mechanism of the inhibitory effect is discussed along with the possible biological and clinical implications of the experimental findings.