CD4 and asthma: The study showed that the ratio of either NKT cells or CD4+NKT cells in children with asthma was significantly lower than the control group (P < 0.01), while the ratio of peripheral blood NKT cells and CD4+NKT cells showed no significant difference among children with different severity of asthma (P > 0.05), which may be associated with the small number of cases in this study.