Regulation of some functions of granulocytes by zinc of the prostatic fluid and prostate tissue.

Oxygen consumption, phagocytosis, and activity of hexosomonophosphate shunt (HMS) of dog and human polystyrene latex-activated polymorphonuclear leukocytes were inhibited by normal and infected human prostatic fluid (PF) and prostate extract; resting cells were not affected. Granulocytes incubated in 7 per cent PF increased five times their zinc content. Inorganic zinc added to synthetic medium which contained activated granulocytes also inhibited O2 consumption and phagocytosis of yeast particles in a concentration-dependent manner; resting cells were not affected. Incubation of PF with CaNa2 ethylenediamine tetraacetic acid (EDTA) abolished the inhibitory effect of PF; extensive dialysis of PF against this chelating agent reduced the inhibition by half. After the PF was dialyzed against saline, the low molecular weight dialysate retained inhibitory effects. Extracts from dog liver, spleen, and human saliva were not inhibitory. Polyamines, which next to zinc are also present in PF in high concentrations, had no effect on granulocytes, O2 consumption, and HMS activity. Human as well as dog PF were inhibitory to human or dog granulocytes, respectively. Besides granulocytes, rat peritoneal macrophages were inhibited by PF as well. It is concluded that PF and extract from prostate inhibit various functions of phagocytes mainly because of high concentration of zinc. The existence of other, large molecular weight, heat-resistant substances in PF which contribute to zinc effect cannot be ruled out.