Chemotactic factor-specific desensitization of skin to infiltration by polymorphonuclear leukocytes

The accumulation of polymorphonuclear leukocytes (PMNs) was measured in rabbits following single or repeated injections into skin sites of the inflammatory agents, zymosan-activated plasma and formylmethionyl-leucyl-phenylalanine. Fewer cells entered lesions restimulated with the same agent during the subsequent inflammatory response than simultaneously entered skin sites stimulated for the first time. Decreased reactivity of a restimulated site was specific to the initiating stimulus, developed within 2 to 4 h of initial stimulation and persisted for at least 8 h. The results indicate that PMN accumulation in acute inflammatory lesions is regulated locally by a chemotactic factor-specific mechanism which differs from PMN deactivation and concentration gradient mechanisms currently thought to regulate PMN migration in vivo.