Chemistry and biology of the anaphylatoxin related serum peptide system. III. Evaluation of leucotactic activity as a property of a new peptide system with classical anaphylatoxin and cocytotaxin as components

Preparations of crystallized classical anaphylatoxin (CAT) from hog, rat and guinea pig serum display no significant chemotactic activity for neutrophil leucocytes. A newly discovered and crystallized basic peptide from hog, rat and guinea pig serum, tentatively called cocytotaxin (CCT), which is similar in its physicochemical behavior to CAT, displays neither significant CAT activity nor significant chemotactic activity for neutrophil leucocytes. Recombination of CAT and CCT in different molar ratios leads to chemotactic activity for neutrophil leucocytes in vitro. Such activity was ascribed by previous authors to a molecular property of other anaphylatoxin preparations. Chromatographically it was possible to demonstrate that our “chemotactically active” CAT preparations are paucidisperse systems. Furthermore, evidence is presented that chemotactic activity for neutrophil leucocytes of CAT preparations still containing CCT is not due to formation of a stable complex of the two peptides. Based on the results presented, it is concluded that chemotactic activity for neutrophil leucocytes is, in this instance, a property of a peptide system for which the name “anaphylatoxin‐related leucotactic peptide system” (ACLsystem) is suggested. Phenomenologically, two types of biological activities are at present known to be elicited by the ACL‐system: 1. anaphylatoxin activity as a property of the CAT molecule. 2. chemotaxis for neutrophil leucocytes as a property of the combined action of CAT and CCT within the ACL‐system.