`Tuftsin': a Natural Phagocytosis Stimulating Peptide

WE have shown in this laboratory that a specific cell bound leucophilic γ-globulin fraction, leucokinin, is essential for maximal stimulation of the phagocytic activity of the blood neutrophilic leucocyte^1,2. We now report that the whole stimulatory effect of leucokinin can be ascribed to a single peptide fragment liberated by a specific enzyme in the outer membrane of the neutrophile. We shall refer to this peptide as `tuftsin' (after Tufts University) and to the enzyme as leucokininase. The peptide `tuftsin' has been produced in vitro from a γ-globulin fraction, PC IV, by treatment with leucokininase. PC IV is prepared by chromatography on phosphocellulose columns³ and contains all the leucokinin activity of serum γ-globulin².