Roles of interleukin-12 family in mycobacterial infection

Interleukin-12 (IL-12) has been considered as an important cytokine in the induction and maintenance of T helper type 1 (Thl) cell-mediated immune response.The common p40 subunit of IL-12/23,which has been well studied,may play a certain role in the counteraction against bacteria,especially mycobacteria,via competitively binding with the β1 chain of IL-12 receptor in monomeric or homodimeric forms.High-virulent mycobacteria may counteract the host immune response by inhibiting the production of IL-12p70.IL-23 may also have a critical role in the protection against chronic mycobacterial infection by inducing the activation of Th17 cells and memory T lymphocytes.However,the function of IL-23 is limited when the production of IL-12 is normal.The roles of IL-27 (the third member of IL-12 family) in host immune response to mycobacterial infection remain controversial,and its effect on different cell populations,such as macrophages and lymphocytes,may be different,even contrary. Key words: Mycobacterium infections;  Interleukins;  Cytokines