IL6 and asthma: The expression of IL-6 and IL-6 receptor has been proven and described in the early stages of lung development.[29] It has been proven that the functional single nucleotide polymorphism of IL-6 was correlated with decline of FEV1 of smoker.[30] IL-6 was identified as negatively associated with FVC.[31] Wang et al[32] had suggested that the IL-12 level was significantly lower in asthma patients, and the IL-12 level was positively associated with FEV1.