CLA reduces antigen-induced histamine and PGE(2) release from sensitized guinea pig tracheae

Conjugated linoleic acid (CLA) has been shown to enhance immune reactions s uch as lymphocyte blastogenesis and delayed-type hypersensitivity. We inves tigated the role of CLA in type I (immediate) hypersensitivity, using a gui nea pig tracheal superfusion model for measuring antigen-induced airway smo oth muscle contraction and inflammatory mediator release. Female Hartley gu inea pigs were fed a diet supplemented with 0.25 g corn oil or linoleic aci d/100 g of diet (control) or 0.25 g CLA/100 g of diet for at least 1 wk bef ore and during active sensitization to ovalbumin antigen. Tracheae from sen sitized guinea pigs were suspended in air-filled water-jacketed (37 degrees C) tissue chambers in a superfusion apparatus. Tracheae were superfused wi th buffer containing antigen, and tissue contraction was recorded. Superfus ate was collected at 90-s intervals for evaluation of histamine and PGE(2) release. CLA did not affect antigen-induced tracheal contractions when expr essed as gram contraction per gram tissue. CLA significantly reduced antige n-induced histamine and PGE(2) release. CLA appears to decrease release of some inflammatory mediators during type I hypersensitivity reactions.