CATABOLISM OF NATIVE AND DENATURED SERUM 131I-PROTEINS BY POLYMORPHONUCLEAR LEUCOCYTES

The physiological role of the peritoneal polymorphonuclear leucocytes (PMNL) in serum protein breakdown has been investigated by incubating PMNL in the presence of serum protein fractions labelled with 131I and used as unscreened, or after screening in vivo or, in the case of γ-globulin, also as aggregates (gga). PMNL incubated either in stationary or in suspended cultures have been found capable of breaking down very small proportions of molecules altered during the fractionation and iodination procedures. On the other hand, no liberation of non-protein 131I was found when using screened samples. The conclusion has been reached that, in the experimental conditions here used, PMNL do not catabolise 131I-proteins that behave like native ones. Rapid breakdown occurred when homologous 131I-γ-globulin was presented to the PMNL as aggregates. The catabolism proceeds almost linearly with time and can be stopped by excluding the cells. © 1968.