POSSIBLE ROLES OF PROTEIN-KINASES IN NEUTROPHIL CHEMOTACTIC FACTOR PRODUCTION BY LEUKOCYTES IN ALLERGIC INFLAMMATION IN RATS

1 In an air pouch-type allergic inflammation model in rats, leucocytes that had infiltrated into the pouch fluid collected 4h after the anti gen challenge produced proteinaceous chemotactic factors for neutrophi ls when they were incubated in the medium. 2 To clarify the mechanism of activation of the infiltrated leucocytes in producing these factors , the effects of protein kinase inhibitors on neutrophil chemotactic f actor production were examined. 3 When the infiltrated leucocytes were incubated for 4h in medium containing the non-selective protein kinas e inhibitor K-252a (1-100 ng ml(-1), 2.14-214 nM), the tyrosine kinase inhibitor genistein (1-50 mu g ml(-1), 3.7-185 mu M), and the more se lective protein kinase C inhibitor H-7 (5-100 mu g ml(-1), 13.7-274 mu M); neutrophil chemotactic activity in the conditioned medium was dec reased in a concentration-dependent manner, but the adenosine 3':5'-cy clic monophosphate (cAMP)-dependent protein kinase inhibitor H-89 (1-1 000 ng ml(-1), 2.24-2240 nM) showed no effect. 4 Isoelectric focusing of the conditioned medium revealed that the leucocytes produced two ne utrophil chemotactic factors, leucocyte-derived neutrophil chemotactic factor (LDNCF) 1 and LDNCF-2. Treatment of the leucocytes with K-252a , genistein, and H-7, but not H-89, inhibited production of both LDNCF -1 and LDNCF-2. 5 These results suggest that activation of tyrosine ki nase and protein kinase C, but not cAMP-dependent protein kinase, is r esponsible for the production of LDNCF-1 and LDNCF-2. 6 The steroidal anti-inflammatory drug dexamethasone and the protein synthesis inhibit or cycloheximide inhibited neutrophil chemotactic factor production in a concentration-dependent manner. Time-course experiments showed that the inhibitory effect by dexamethasone was apparent even 30 min after the incubation.7 Mechanism for inhibiting the production of LDNCF-1 a nd LDNCF-2 by dexamethasone is also discussed.