Anti-inflammatory cytokines in asthma and allergy: interleukin-10, interleukin-12, interferon-gamma

INTERLEUKIN-10 (IL-10) is a cytokine derived from CD4+ T-helper type 2 (TH2 ) cells identified as a suppressor of cytokines from T-helper type 1(T-H1) cells. Interleukin-12 (IL-12) is produced by B cells, macrophages and dendr itic cells, and primarily regulates TH1 cell differentiation, while suppres sing the expansion of T-H2 cell clones. Interferon-gamma (IFN-gamma) is a p roduct of TH1 cells and exerts inhibitory effects on TH2 cell differentiati on. These cytokines have been implicated in the pathogenesis of asthma and allergies. In this context, IL-12 and IFN-gamma production in asthma have b een found to be decreased, and this may reduce their capacity to inhibit Ig E synthesis and allergic inflammation. IL-10 is a potent inhibitor of monoc yte/ macrophage function, suppressing the production of many pro-inflammato ry cytokines. A relative underproduction of IL-10 from alveolar macrophages of atopic asthmatics has been reported. Therapeutic modulation of T-H1/T-H 2 imbalance in asthma and allergy by mycobacterial vaccine, specific immuno therapy and cytoline-guanosine dinucleotide motif may lead to increases in IL-12 and IFN-gamma production. Stimulation of IL-10 production by antigen- specific T-cells during immunotherapy may lead to anergy through inhibition of CD28-costimulatory molecule signalling by IL-10s anti-inflammatory effe ct on basophils, mast cells and eosinophils.