The most prominent effect is seen in the expression of cd4-1, cd4-2.1 and the Th1 marker tbx21. Although dexamethasone-treated fish are able to induce an IFN-γ response against mycobacteria, the suppression of specific T cell populations, together with the induction of the inhibitory cytokine tgfb1b, are associated with compromised ability to control infection. Here, TBX21 is linked to infection.