We have prepared T-cell clones from bronchoalveolar lavage fluid (BALF) from four healthy, nonsmoking persons and from four patients with allergic asthma. T cells were cloned by direct limiting dilution and with the use of a fluorescent activated cell sorter with an automated cell deposition unit. T-cell clones from the blood (PB) were prepared as well. The cloning efficiencies of T cells from BALF ranged from 3 to 40% and were lower than those obtained from PB T cells (18 to 72%). The cloning conditions generated CD4+ as well as CD8+ clones. The very late antigen-4, VLA-4, was more frequently expressed on CD4+ T-cell clones from BALF than from the blood (P < 0.05). CD8+ clones from BALF were more frequently VLA-1+ than those from blood (P < < 0.01). Mitogen- and monoclonal antibody-driven proliferation of CD4+ clones showed that BALF clones were well responsive to proliferation stimuli similar to those from the blood. Analysis of interleukin-4 production by 10 BALF and 10 PB clones showed large variations between individual CD4+ clones (BALF: range, < 100 to 700 pg/ml; PB: range, < 100 to 1,100 pg/ml), indicating the generation of different types of clones, which was also clear from analysis of interferon-gamma production. The analysis of properties of BALF T-cell clones and their regulation will improve insight into immunologic reactions in the lungs.

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SUMMARYIn patients with allergic asthma, T-cell cytokines are implicated in the regulation of the local inflammation in the airways. The ability of sensitized mast cells to release mediators and cytokines early upon allergen stimulation makes them important candidates for local immunoregulation. We have studied the effects of human mast cells on T cells with the use of the human mast cell line HMC-1. We showed that activated human mast cells or their soluble products induced and enhanced the interferon-c (IFN-c) production by T cells up to about 60-fold. The production of interleukin (IL)-4 was hardly affected and that of IL-5 was slightly enhanced. The enhancement of IFN-c production was induced both in polyclonal CD4 + and CD8 + T cells and in CD4 + and CD8 + T-cell clones. Further characterization of the factors involved demonstrated a molecular mass above 30 000. Our results implicate that by this mechanism mast cells may account for a negative feedback system locally down-regulating allergen-induced T helper 2 responses via IFN-c production by the T cells.

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