A novel cleavage product of beta-thromboglobulin formed in cultures of stimulated mononuclear cells activates human neutrophils.

A neutrophil-activating peptide, NAP-2, was found to be produced in cultures of human mononuclear cells in the presence of E. coli lipopolysaccharide or phytohaemagglutinin. NAP-2 induced the release of elastase from cytochalasin B-treated human neutrophils. Amino- and carboxy-terminal sequencing and electrophoretic analysis showed that NAP-2 is a single peptide of 70 amino acids (Mr 7,628, IEP 8.7) corresponding to a carboxyterminal fragment of beta-thromboglobulin. NAP-2 is homologous to NAF/NAP-1. When aligned on the basis of their two first cysteines, 13 out of 20 amino-terminal residues are identical. The overall homology between the two peptides is 46%.