EICOSANOID RELEASE AND MEPYRAMINE, LTC4 AND LTD4 BINDING IN PASSIVELY SENSITIZED HUMAN LUNG PARENCHYMA INVITRO

In vitro passive sensitization of human lung parenchyma with hyper-immune serum did not affect the release of prostaglandin D2 (PGD2) or leukotriene (LT)-like activity upon challenge with anti-IgE antibody with respect to control lung, despite a marked difference in IgE levels between control (C) and sensitized (S) tissue. Binding studies with [H-3]LTC4, [H-3]LTD4 and [H-3]mepyramine (a histamine H-1 antagonist) showed a statistically significant increase in the amount bound in sensitized vs control lung for [H-3]mepyramine only. Contractile response to 5 x 10(-5) M histamine (H) in C and S lung parenchymal strips did not correlate with binding data. It is concluded that in vitro elevated IgE levels do not affect the interaction of sulfidopeptide leukotrienes with their putative receptors. As for the observed increase in [H-3]mepyramine binding, this might not represent a true increase in histamine receptors on lung smooth muscle cells.