Immunostimulatory CpG oligodeoxynucleotides stimulate expression of IL-1 beta and interferon-like cytokines in rainbow trout macrophages via a chloroquine-sensitive mechanism

Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs a re known to stimulate immune responses and are potent adjuvant's in higher vertebrates, but so far the effects in fish are poorly described. We here r eport that CpG ODNs induce IL-1 beta expression and production of interfero n-like cytokines in rainbow trout head-kidney macrophages, whereas ODNs wit h an inverted motif (GpC) have a much less stimulatory effect. We further d emonstrate that endosomal maturation is essential for CpG signalling, as ch loroquine, a compound known to block endosomal acidification, inhibits cyto kine expression in the macrophages. (C) 2001 Academic Press.