CD8A and bacterial infectious disease: Additionally, a strong trend toward increase of MHC-I expression was observed at 9 h post-bacterial infection in the rTH2-3-supplemented fish compared controls (Figs. 8j and 9j), indicating an activation of both cytotoxic and CD8 + suppressor T-lymphocyte host-defense mechanisms that together reflect overall immune function (i.e. CD4 + T-lymphocytes activation, phagocytes recruitment, and B cell activation)69,70.