OBJECTIVE:To study the relationship between PPD reaction and serum ECP and IgE levels, and cytokines expression in children with acute bronchial asthma. METHODS: The PPD test was performed, serum levels of ECP and IgE were determined and the expressions of IFN-γ, IL-4 and IL-12 P40 mRNA in the peripheral blood were determined following PPD stimulation in 32 asthmatic children. Eight healthy children served as the controls. RESULTS: The number of PPD negative responders (n= 24) were significantly greater than that of PPD positive ones (n= 8). Of the 24 children with negative PPD, 16 (66.7%) had moderate or severe asthma attacks and only 2 cases (25.0%) in the 8 children with positive PPD (66.7% vs 25.0%, P < 0.05). The levels of ECP and IgE were higher in the PPD negative patients than those in the PPD positive patients ( P < 0.05). After PPD stimulation in the asthmatic patients there was no significant change of IL-12 mRNA and IFN-γ mRNA expressions, while IL-4 mRNA expression increased compared with the healthy children ( P < 0.05). CONCLUSIONS: There might be cellular immunity deficiency in PPD negtive patients. The immunoenhancement effect following PPD stimulation is suppressed in asthmatic patients.