Inhibition of cytokine-induced expression of T-cell cytokines by antihistamines.

OBJECTIVE To investigate immunomodulatory properties of 4 antihistamines available in Japan. METHOD Isolated peripheral blood T cells from healthy volunteers were preincubated with cetirizine, loratadine, olopatadine, or fexofenadine for 30 minutes and then stimulated with interleukin (IL)-1 2 or IL-4 to skew immune response towards type 1 or type 2 helper T cells. RNA was extracted 6 hours later and semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was performed using primers for IL-5 and interferon (IFN) gamma. Supernatants were collected 24 hours after stimulation, and cytokine production was quantified by enzyme-linked immunosorbent assay (ELISA). RESULTS RT-PCR revealed that IL-12-induced expression of IFN-gamma was partially suppressed by loratadine and fexofenadine and that all 4 agents tested inhibited IL-4-induced expression of IL-5. ELISA demonstrated that IL-12-induced IFN-gamma production was significantly suppressed by cetirizine and fexofenadine and IL-4-induced IL-5 production was downregulated by three agents with the exception of cetirizine. This study demonstrates that antihistamines have varying immunomodulatory properties, suggesting treatment choice for atopic dermatitis can be directed by disease signs and symptoms.