Cytokine mRNA expression in cattle infected with different dosages of Mycobacterium bovis

The expression levels of all the four cytokines gradually increased in cattle infected with 1 cfu-1000 cfu. Statistical significance (P < 0.05) was observed for the cytokines IFN-γ, IL-4 and IL-10 between the cattle infected with 1 cfu and 1000 cfu. Though there was an increase in the expression levels of TNF-α from cattle infected with 1 cfu-1000 cfu, this difference in expression was not statistically significant (P > 0.05). The increase in the levels of IFN-γ indicates that the host may be responding to control the infection and the increased level of IL-4 and IL-10 which are anti-inflammatory cytokines, suggests that these cytokines are trying to protect the host by reducing the inflammation and also by controlling the levels of TNF-α (the cytokine that may cause tissue damage).