Possible participation of macrophage inflammatory protein 2 in neutrophil infiltration in allergic inflammation in rats.

Recombinant rat macrophage inflammatory protein 2 (MIP-2) was prepared from E. coli transfected with a glutathione-S-transferase (GST)-MIP-2 fusion protein expression vector. A polyclonal antibody to rat MIP-2 was then obtained from rabbits by immunization with recombinant rat MIP-2. Using the polyclonal antibody which selectively suppressed neutrophil chemotactic activity of MIP-2, the role of MIP-2 in neutrophil infiltration in allergic inflammation in rats was studied. In an air pouch-type allergic inflammation model in rats, neutrophil infiltration into the pouch fluid increased with time after antigen challenge. Neutrophil chemotactic activity in the pouch fluid collected 8 h after antigen challenge was diminished by anti-MIP-2 antibody. In addition, when leukocytes that had infiltrated into the pouch fluid collected 4 h after antigen challenge were incubated, neutrophil chemotactic activity in the conditioned medium increased time-dependently, and the activity was neutralized by anti-MIP-2 antibody. Furthermore, when anti-MIP-2 antibody was injected into the pouch 6 h after antigen challenge, neutrophil infiltration into the pouch fluid during the next 2 h was suppressed. These findings indicate that MIP-2 plays an important role in neutrophil infiltration in rat allergic inflammation.