Enhancement of phagocytic and chemokinetic activities of rainbow trout head kidney cells by C-reactive protein

Objective-To investigate immunostimulating activity of purified rainbow tro ut (Oncorhynchus mykiss) C-reactive protein (CRP) on trout phagocytic cells . Animal-20 rainbow trout and 2 rabbits. Procedure-The effect of CRP on phagocytic activity of head kidney (HK) cell s was examined by use of a phagocytosis assay with plastic particles. The e nhancing effect of CRP on migration activity of HK cells was examined by us e of the blind well assay. Results-Glass-adherent cells from clinically normal trout had increased dos e-dependent phagocytic activity against plastic particles when cells were i ncubated in the presence of CRP. Pretreatment of particles with CRP also en hanced phagocytic activity of the cells, indicating an opsonic effect of CR P. Rabbit anti-trout CRP serum suppressed the enhancing activity of CRP. Th e HK cells had significant dose-dependent chemokinetic activity against CRP that was not inhibited by anti-CRP serum, indicating that a CRP-antibody c omplex also could be chemokinetic. Conclusions-Rainbow trout CRP has immunostimulating activity for HK cells, resulting in enhanced phagocytic and chemokinetic activities.