Cyclic tetrameric clusters of chemotactic peptides as superactive activators of lysozyme release from human neutrophils.

The preparation of cyclic tetramers of formyl-methionyl-leucylphenylalanine (FMLP) amides from tetraazacycloalkanes incorporating different spacers is described. The corresponding monomeric analogs are also reported. The ability of these FMLP analogs to release lysozyme from human neutrophils was evaluated. The cyclic clusters proved to be superactive and in a manner suggestive of a cooperative response of the membrane receptors. The spasmogenicity of two prototype compounds on the guinea-pig ileum was also measured and the results briefly discussed.