Biochemistry and Biology of a Leucotactic Binary Serum Peptide System Related to Anaphylatoxin

Abstract

The purification and crystallization of the peptide components of a newly detected binary peptide system in mammalian serum (hog, rat and guinea pig) is described. The peptide system consists of two components, classical anaphylatoxin and cocytotaxin. Cocytotaxin represents a hitherto unknown basic peptide of mammalian serum which has been modified by a contact reaction with immune complexes or other hydrophilic, insoluble substances of high molecular weight. The molecular homogeneity of both crystallized peptides has been established. Classical anaphylatoxin has a molecular weight of 9,500, and cocytotaxin, which is highly similar in its physicochemical behaviour to anaphylatoxin, has a molecular weight of 8,500. Products of an enzymatic reaction with anaphylatoxin and cocytotaxin as substrates have been isolated and characterized as three proteins with molecular weights of 28,000, 56,000 and 112,000. The biological activities of both low molecular peptides were investigated. Anaphylatoxin is a well-known histamine liberator in guinea pigs and elicits anaphylactic reactions. Cocytotaxin, although physicochemically similar to anaphylatoxin, produces none of the actions of anaphylatoxin and has no known separate biological activity. Neither anaphylatoxin nor cocytotaxin display significant chemotactic activity for neutrophils. On recombination and depending on their molar ratio and the absolute concentration of each of the peptides, cell-specific chemotactic activity for neutrophil and eosinophil leucocytes is observed. Cell-specific leucotactic and anaphylatoxin activities could be demonstrated to be different activity phases of the binary peptide system with only a partial overlap. The mechanism of action of this peptide system on cells was evaluated. It was found that cocytotaxin can be replaced by nucleotides such as ATP, cyclic AMP etc., suggesting that cocytotaxin acts as regulatory peptide and that the energy metabolism is activated by anaphylatoxin as catalytic peptide. Considering the pharmacological activities of the three metabolites of the peptides, a relationship between chronic inflammation and circulatory disease may be assumed.

A Specific Inhibitor of Complement (C5)-Derived Chemotactic Activity in Serum from Patients with Systemic Lupus Erythematosus

“…It is, however, chem-otactically active in the presence of small amounts of normal uinactivated serum. These findings are similar to those of Wissler et al (46) who described a serum "helper" factor ("cocytotaxin") required for the expression of chemotactic activity by C5a-derived peptides. In light of these findings, it is possible that the inhibitor described above might interact with either a C5a-derived chemotactic peptide or with a "helper" factor present in serum.…”

“…Further delineation of its mechanism of' action must await precise identification of'the biologically active peptides derived from C5 as a consequence of' complement activation. Whereas one of these peptides, the C5a anaphylatoxin, has been purified to homogeneity and demonstrated to have chemotactic and PMN lysosomal enzyme-releasing activities (41)(42)(43), it remains unclear whether this peptide accounts for the bulk of the chemotactic activity generated in whole serum by complement activation (12,(44)(45)(46)(47). The possibility remains that there are a number of closely related C5-derived peptides that possess similar biologic activities, either singly or in combination.…”

Monocyte and Neutrophil Chemotactic Activity of Normal and Diluted Human Serum and Plasma

“…The Millipore filter technique [3] allowed dem onstration of chemotactic derivatives, either after in vitro interaction of purified serum components [1,11,22] or after activation of native serum followed by isolation of the active factors [3,11,17,26]. These studies led to the conclusion that an important role in leukocyte chemoattraction is ascribable to complement-split products, although some results are still controversial.…”

Effect of Exogenous Cyclic AMP and other Adenine Nucleotides on Neutrophil Chemotaxis and Motility

“…[6] have been unable to detect in vitro chemotactic activity of cyclic AMP for neu trophils. In contrast, Leahy et al [1], Ramsey [2], Gammow et al [3] and now ourselves have succeeded.…”