Study of the Th1/Th2 balance, including IL-10 production, in cultures of peripheral blood mononuclear cells from birch-pollen-allergic patients

Background: Excessive production of interleukin (IL)-4, IL-5, IL-10, and IL-13 is thought to be important in the development of allergy and asthma. The objective of this investigation was to study Th1/Th2-like cytokine profiles in vitro in seven patients allergic to birch pollen and six nonallergic controls during the birch-pollen season. Methods: Peripheral blood mononuclear cells (PBMC) were isolated and cultured with birch-pollen extract (BPE) or tetanus toroid (TT) for 7 days, harvested, and restimulated with the mitogens phytohemagglutinin (PHA) and phorbol 12-myristate 13-acetate (PMA) for 24 h. Cytokine production was determined by ELISA, and logarithmic cytokine ratios were compared between the two groups and between the antigens. Results: Tn the allergic group, the cultures prestimulated with BPE had a more Th2-like cytokine response than the TT-prestimulated cultures; i.e., lower IFN-gamma and higher IL-10 production (P < 0.05), as well as higher IL-5/IFN-gamma and IL-13/IFN-gamma ratios (P < 0.05). There were also significantly higher IL-4/IFN-gamma (P < 0.005) and IL-5/IFN-gamma (P < 0.05) ratios in BPE-stimulated cultures in the allergic group than in the control group. The IL-4 and IL-13 production in vitro correlated with the specific serum IgE levels. Conclusions: BPE stimulation induces a Th2-like cytokine response by PBMC isolated during the pollen season from birch-pollen-allergic patients, indicating a Th2-type immune response to birch pollen in vivo.