The role of protein kinase C in regulating equine eosinophil adherence and superoxide production

Objective: To determine if protein kinase C (PKC) regulates equine eosinophil function.Material or subjects: Blood eosinophils were obtained from healthy ponies.Methods: IL-5- and histamine-induced adherence to serum-coated plastic was measured as the eosinophil peroxidase content of adherent cells and serum treated zymosan (STZ)-and IL-5-induced superoxide production by the reduction of cytochrome C. Eosinophil PKC activity was quantitated as the rate of transfer of ³²P from ATP to substrate. The effects of Ro31-8220 (isotype non-selective PKC inhibitor), Gö6976 (conventional PKC inhibitor), and rottlerin (PKC inhibitor) were determined by ANOVA and Bonferronis or Dunnetts test.Results: Ro31-8220 and Gö6976 reduced superoxide production whereas only Gö6976 inhibited adherence. Rottlerin inhibited histamine-induced adherence and increased STZ-induced superoxide production. Ro31-8220 and Gö6976, but not rottlerin, inhibited PKC activity.Conclusions: PKC is involved in regulating equine eosinophil adherence and superoxide production. The role of PKC appears to depend upon the stimulus used and response measured.Received 13 September 2004; returned for revision 19 October 2004; accepted by N. Boughton-Smith 4 November 2004