Comparison of antigen and Ca++-ionophore-induced peptidoleukotriene release from guinea pig lung preparations using...

This study was undertaken to investigate antigen-induced peptidoleukotriene release from lungs of sensitized guinea pigs using a recently developed solid-phase extraction and high-performance liquid chromatography assay system. This release was compared to the response due to Ca++-ionophore (A23187) challenge. Incubation of lung fragments (0.6 g) from actively sensitized guinea pigs with ovalbumin (3 micrograms/ml) for 20 min at 37 degrees C resulted in the release of 40 to 60 ng of leukotriene (LT)D4 detected in the extracted filtrate (40-50% recovery of LTD4). The amount of LTD4 determined using the high-performance liquid chromatography assay correlated well with the quantity determined by a LTC4 radioimmunoassay. LTD4 release was saturable and was optimal at a tissue concentration of 0.6 g/2.5 ml of buffer. Kinetic analysis of LT generation showed that after antigen challenge, LTC4 levels peaked at 3 min and declined rapidly with time; LTD4 levels then increased significantly, reaching a maximum at 15 min and decreased slightly at 60 min. LTE4 was not detected until 30 min after antigen challenge after which it increased slowly. The kinetic results permit an estimation of the rate of LTD4 and LTE4 formation to be 5 and 0.17 ng/min/g of lung, respectively. In contrast to antigen challenge, LTD4 release from Ca++-ionophore-stimulated lung fragments was not saturable and was biphasic with increasing amounts of tissues. Moreover, LTD4 produced by Ca++-ionophore stimulation could not be detected during the first 10 min but thereafter increased linearly with incubation time.(ABSTRACT TRUNCATED AT 250 WORDS)