Expression of chemokine (CXCL8_L2, CXCa_L1, CXCb) and chemokine receptor (CXCR1 and CXCR2) genes in head kidney phagocytes (A–C) or in monocyte/lymphocyte- (1.020–1.060 g/cm3), macrophage- (1.060–1.070 g/cm3) and granulocyte- (1.070 to 1.083 g/cm3) enriched fractions from head kidney (C). Cells were stimulated with poly-inosinic poly cytidiylic (Poly I∶C, 50 µg/ml) or phytohemagglutinin (PHA, 10 µg/ml) (A) or with lipopolysaccharide (LPS) (B–D). Data are shown as x-fold increase of mRNA expression compared to non-stimulated control cells standardized for the housekeeping gene 40S ribosomal protein s11. Averages (n = 4–6 for Fig. 5A–C and n = 9 for Fig. 5D) and SD are given. *, p<0.05, **, p<0.01.