IL-12 RB1 Genetic Variants Contribute to Human Susceptibility to Severe Acute Respiratory Syndrome Infection among Chinese

Tang, Fang; Liu, Wei; Zhang, Fang; Xin, Zhong-Tao; Wei, Mao-Ti; Zhang, Pan-He; Yang, Hong; Ly, Hinh; Cao, Wu-Chun

Interleukin-12 (IL-12) is a cytokine secreted by activated phagocytes and dendritic cells [14] . It plays a pivotal role in promoting Th1-type immune responses and cell-mediated immunity. IL-12 triggers many biological functions: it stimulates the proliferation of activated T-and NK-cells, enhances T-and NKcell-mediated cytolytic activity, and induces the production of IFN-c by both T-and NK-cells (Trinchieri 1998 ). The interferon-c production induced by IL-12 forms a major link between innate and adaptive immunity [15] . A recent study revealed that interferon-mediated immunopathological events are associated with atypical innate and adaptive immune responses in SARS patients [16] . We thus reasoned that IL-12 might also play a role in resistance to SARS, which is signaled through the direct binding of the IL-12 molecule to its receptor (IL-12R). IL-12R has been shown to consist of at least two distinct subunits, B1 and B2, that associate to form a high-affinity IL-12R complex expressed on activated T-and NK-cells (17, 18) . In the current study, we hypothesized that polymorphisms of the IL-12R B1 gene might be associated with SARS susceptibility. To test this hypothesis, we conducted a case control study to investigate the association between IL-12R B1 genetic polymorphisms and SARS in Chinese individuals.