Reduced IL-12 level correlates with decreased IFN-gamma secreting T cells but not natural killer cell activity in asthmatic children

Background: Accessory cells such as macrophages and natural killer cells, a nd their cytokines such as IL-10, IL-12, and IFN-gamma have been suggested to play a critical role in the development of T helper cells. Objective: Both natural killer cells and peripheral blood mononuclear cells were isolated and stimulated for their ability in producing cytokines, In addition, the percentage of IFN-gamma-secreting cells was analyzed with the method of intracellular staining. Results: The data suggested (1) no significant difference between asthmatic children and normal controls in number, cytotoxicity, and IFN-gamma produc tion of purified NK cells: (2) decreased secretion of IL-12 by stimulated p eripheral blood mononuclear cells in asthmatic children compared with norma ls (P <.05); (3) decreased production of IFN-gamma by PBMC from asthmatic c hildren compared with normals (P <.05); and (4) intracellular expressed IFN -gamma level was lower in CD4(+) T cells of asthmatic children (P <.05). Conclusion: The results suggested that IL-12 produced predominantly by macr ophages and associated decreased IFN-gamma-secreting CD4(+) T cells play a critical role in the pathogenesis of asthma.