BACKGROUND:Interleukin (IL)-10 is a pleiotropic cytokine released from various cells, including T cells. Although IL-10 is suggested to inhibit allergic responses, its role in asthma remains uncertain. The purpose of the present study was to compare the profile of IL-10 in circulating T cells from stable atopic asthmatics, atopic nonasthmatics and healthy controls.
METHODS:Peripheral blood mononuclear cells were isolated, stained with anti-CD3 and CD4/CD8 antibodies, and then processed for intracellular IL-10 detection by flow cytometry.
RESULTS:A kinetic study in healthy controls showed that stimulation with phorbol 12-myristate 13-acetate and ionomycin significantly increased the frequencies of IL-10-producing CD3+, CD4+and CD8+cells. Without stimulation, the frequencies of IL-10-producing CD3+, CD4+and CD8+cells were significantly higher in asthmatics than in healthy controls, while a similar trend was observed in atopic nonasthmatics. Stimulation for 24 h significantly increased IL-10-producing CD3+, CD4+and CD8+cells in healthy controls and atopic nonasthmatics, but not in asthmatics.
CONCLUSIONS:The frequency of IL-10-producing T cells is increased in the circulation of stable atopic asthmatics compared with normal controls. The lack of enhancement in their frequency by phorbol 12-myristate 13-acetate and ionomycin in asthmatics suggests that the circulating T cells of asthmatic subjects are maximally stimulated with regards to IL-10 production; alternatively, IL-10 production by T cells from asthmatics may be regulated differently than T cells from other subjects.