IL-1 receptor-type expression in relation to atopy

Background: IL-1 has 2 receptors, type I (IL-1RI) and type II (IL- 1RII), which have 2 forms each, membrane (m) and soluble (s). When IL-1 binds to mIL-1RI, the active receptor, an inflammatory response is initiated, which does not occur when IL-1 binds to mIL-1RII, the decoy receptor. Both sIL-1RI and sIL-1RII function as IL-l-mopping mechanisms. We hypothesized that the ratio of active (mIL-1RI) to inactive (mIL-1RII, sIL-1RI, and sIL-1RII) receptors is important in determining the amount of inflammation produced in allergic reactions. Objective: Our aim was to compare the concentrations of mIL-1RI and mIL-1RII on cultured PBLs and sIL-1RI, sIL1RII, and IL-1β in sera and supernatants of cultured PBMCs from atopic and nonatopic subjects. Methods: The membrane receptors, soluble receptors, and IL1β concentrations were measured by ELISA with specific mAbs. Results: Although there was no difference in the level of serum IL-1β between the 2 groups, PBMCs from atopic persons spontaneously secreted higher levels of IL-1β than those from nonatopic donors (P <.05). PBLs from atopic subjects compared with those from nonatopic individuals expressed higher mIL-1RI (P <.0001) and mIL-1RII (P <.05). Levels of both the soluble receptors from both serum (P <.0001) and PBMCs (P <.05) of nonatopic donors were higher than those found in atopic donors. Conclusion: This augmentation of mIL-1RI concomitant with a reduction in soluble receptors may be an important contributory factor to the inflammation that occurs with allergen exposure.