Allergen-specific cytokine production in human peripheral blood mononuclear cells from peanut-allergic subjects in vitro

Abstract

The underlying molecular event of peanut allergy is not well understood. The objectives of this study were (1) to characterize cytokine production by PBMCs from peanut allergic individuals, and (2) to determine whether IL-10 can interfere cytokine production. PBMCs were isolated and cultured for 5 days in the presence of peanut extract (2mg/ml), with or without IL-10 (10ng/ml), from subject with true peanut allergy (group 1), subjects with positive peanut skin test who tolerate peanut ingestion (group 2), subjects with positive peanut skin test who never have known peanut exposure (group 3) and health controls (group 4). Cytokines, including IFN-gamma, IL-5, IL-10, IL-2, GM-CSF, TNF-alfa, IL-1beta, IL-6 and IL-8 were measured from culture supernatant with LuminexTM multiple ELISA. There was no difference in the constitutive production of cytokines among groups. Upon peanut stimulation, group 1 produced significantly more IL-5, IL-10, IL-2, and likely more TNF-alfa and less IFN-gamma than other groups. Productions of GM-CSF, IL-1beta, IL-6 and IL-8 were significantly augmented upon peanut allergen stimulation in all groups. Production of all the cytokines was significantly inhibited by exogenous IL-10. The increased ability to produce Th2 cytokines in group 1 was associated with a significantly higher total IgE (p=0.01) and peanut specific IgE (p<0.01) compared to group 4. Further analysis on the differences between the four groups and the costimultory molecule expression is one the way. Our results provided corroborating evidence that peanut allergy is a Th2-driven process, and IL-10 has strong suppressive effects on cytokine productions in vitro.