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

Abstract

Objective - To investigate immunostimulating activity of purified rainbow trout (Oncorhynchus mykiss) C-reactive protein (CRP) on trout phagocytic cells. Animals - 20 rainbow trout and 2 rabbits. Procedure - The effect of CRP on phagocytic activity of head kidney (HK) cells was examined by use of a phagocytosis assay with plastic particles. The enhancing effect of CRP on migration activity of HK cells was examined by use of the blind well assay. Results - Glass-adherent cells from clinically normal trout had increased dose-dependent phagocytic activity against plastic particles when cells were incubated in the presence of CRP. Pretreatment of particles with CRP also enhanced phagocytic activity of the cells, indicating an opsonic effect of CRP. Rabbit anti-trout CRP serum suppressed the enhancing activity of CRP. The HK cells had significant dose-dependent chemokinetic activity against CRP that was not inhibited by anti-CRP serum, indicating that a CRP-antibody complex also could be chemokinetic. Conclusions - Rainbow trout CRP has immunostimulating activity for HK cells, resulting in enhanced phagocytic and chemokinetic activities. (Am J Vet Res 1999;60:240-244).