[Mite-induced interleukin-5 and interleukin-4 expressions in peripheral blood mononuclear cells from asthmatic children with respiratory syncytial virus infection].

OBJECTIVE: To investigate the effects of respiratory syncytial virus(RSV) infection on mite-induced interleukin-5 and interleukin-4 expressions in cultures of PBMC from asthmatic children and their correlation with asthmatic symptoms.

METHODS: IL-5 and IL-4 expressions in mite (D. Pteronyssinus)-stimulated PBMC were assessed ex vivo by ELISA and reverse transcription-polymerase chain reaction (RT-PCR) in 16 allergic asthmatic children with RSV infection(A) and 14 patients without RSV infection(B), as well as 10 normal controls(C) (5.1 +/- 2.4 yrs). Meanwhile their correlation with serum ECP or current wheezing was analysed in patients after RSV infection.

RESULTS: (1) Stimulation of PBMC with mite antigens induced significantly higher IL-4 (34 +/- 24) ng/L vs (8 +/- 5) ng/L, (P < 0.01) and IL-5 (26 +/- 15) ng/L vs (6 +/- 5) ng/L release in allergic patients(B) as compared with healthy controls(C). The release was in a mite dose-dependent manner. Meanwhile, IL-5 level in group A (A) was the highest (73 +/- 47) ng/L, P < 0.05 compared with (B)). Similar results were obtained with IL-5 mRNA expressions. (2) Serum ECP level was significantly higher in group A (73 +/- 47) micrograms/L than in group C (18 +/- 12) micrograms/L, P < 0.01. There was a significant correlation between IL-5 release and ECP levels (r = 0.49, P < 0.05). (3) Mite-induced IL-5 release in PBMC was significantly increased in the group with wheezing symptom (71 +/- 40) ng/L compared with the asymptomatic group (34 +/- 29) ng/L, (P < 0.05).

CONCLUSIONS: Our findings indicated that during RSV infection, mite-induced IL-5 expression in PBMC of asthmatic children was up-regulated, which may enhance activation of eosinophils and precipitate or exacerbate asthma symptoms.