• M L Kuo, J L Huang, K W Yeh, P S Li, and K H Hsieh.
• Health Research Division, Chang Gung Children's Hospital, Taoyuan, Taiwan, Republic of China. mingling@adm.cgmh.org.tw
• Ann. Allergy Asthma Immunol. 2001 Mar 1;86(3):272-6.

BackgroundTh2-type cytokines, such as IL-4 and IL-5, are generally believed to play an important role in the pathogenesis of allergic asthma. In contrast, Th1-type cytokine, especially interferon (IFN)-gamma, is thought to have a downregulatory effect on Th2 immune response cells. Thus, the imbalance of Th1 and Th2 cells may be a key factor in relation to disease severity.ObjectiveThe aim of this study is to examine the changes in the Th1/Th2 ratios and cytokine production profiles of asthmatic children at acute attacks and convalescent stages.MethodsTwelve asthmatic patients were included in this study. The percentages of IFN-gamma- or IL-4-producing cells were determined with a flow-cytometric method of intracellular protein detection. Fresh whole blood obtained from normal controls and patients at two stages was stimulated with brefeldin A, phorbol myristate acetate, and ionomycin for 4 hours. Cells were fixed and stained intracellularly with fluorescein isothiocyanate- or phycoerythrin-conjugated antibody specific to each cytokine in combination with anti-CD4. ELISA assays were applied to measure cytokine concentrations of supernatant from peripheral blood mononuclear cells (PBMC) activated with phorbol myristate acetate and ionomycin for 24 hours.ResultsAmong CD4+ cells, the percentage of IL-4+ cells decreased significantly from 8.18 +/- 4.77% at acute attacks to 4.18 +/- 1.26% (P < .020) at convalescence. The percentage of IFN-gamma+ cells also decreased from 13.49 +/- 4.21% to 9.03 +/- 5.42% (P < .052). The Th1/Th2 ratios of patients at the two stages were similar, and both were lower than the normal controls. Significantly higher IL-5 and lower IFN-gamma production were detected from activated PBMC of asthmatic patients than normal controls.ConclusionsThe decrease of IFN-gamma+ and IL-4+ cells detected at the single-cell level may explain the potential mechanism of convalescence from acute asthma attacks. High Th1/Th2 ratio and low IL-5 production from the PBMC of normal controls support the idea of a biased Th2 immune response in asthmatic patients.

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