Comparative gene expression profile in two Atlantic salmon cell lines TO and SHK-1

TO and SHK-1 are two Atlantic salmon (Salmo salar) cell lines isolated from head kidney cells and used widely in viral diagnostic and fundamental research. Analysis of their resting-state expression levels for a number of immune relevant genes revealed significant differences in expression between the two cell types in the absence of stimulant. TO cells expressed Arginase 1 beta and a CD4-related gene at a significantly higher level than SHK-1. In contrast, SHK-1 cells expressed type I interferon and one of its induced genes (Mx), gammaInterferon-induced Protein (gammaIP) and InterLeukin (IL)-10 at a significantly higher level than TO cells. These results suggest that these two cell lines, although originally isolated from the same organ have potentially very different functional properties. The SHK-1 cell line, or a subpopulation of SHK-1 cells, shares characteristics with dendritic cells whilst the TO cell line shows characteristics more traditionally associated with macrophages.