Fluorine-18 labeled chemotactic peptides: a potential approach for the PET imaging of bacterial infection.

A potent chemotactic peptide, formyl-norleucyl-leucyl-phenylalanyl-norleucyl-tyrosyl-lysine was derivatized by reaction with N-succinimidyl 4-fluorobenzoate. This derivatized peptide bound to human polymorphonuclear leukocytes in vitro and exhibited biological activity in a superoxide production assay. Peptide labeling using N-succinimidyl 4-[18F]fluorobenzoate was accomplished in reasonable yields with 10-15 mCi of labeled peptide available per 100 Ci of [18F]fluoride. With the exception of the gastrointestinal tract, clearance of activity from tissues following injection of this peptide in normal mice was rapid. Although preliminary in nature, these results suggest that 18F-labeled chemotactic peptides should be investigated as potential agents for positron emission tomographic imaging of bacterial infections.