Generation and metabolism of leukotrienes and release of histamine from human dispersed tonsillar cells.

We studied the generation and metabolism of leukotrienes (LT) and the release of histamine by human tonsillar cell suspensions. Human tonsils were dissected and mechanically dispersed. This procedure yielded a single cell suspension with 1.6 +/- 0.5 X 10(8) cells/g tissue consisting of 97.3 +/- 0.4% lymphocytes, 1.4 +/- 0.3% granulocytes, 1.3 +/- 0.3% macrophages/monocytes, and 0.03 +/- 0.02% mast cells/basophils. The cells were stimulated either with Ca-ionophore A 23187, melittin, or anti-human IgE. Determination of the 5-lipoxygenase products LTB4 and LTC4 was performed with specific radioimmunoassays (RIA), and histamine release was measured by the fluorophotometric technique. A time- and dose-dependent release of the mediators was monitored. LTB4 exceeded the amount of LTC4 in the supernatants. The concentration of leukotrienes ranged between 0.8 and 5.4 ng LTB4/1 X 10(8) cells or 0.5 and 1.5 ng LTC4/1 X 10(8) cells, depending on the stimulus. Histamine release after stimulation ranged between 25 and 35% of the total histamine content, whereas buffer controls amounted to 17%. The incubation of the cells (1 X 10(8) with exogenously added LTB4 resulted in the formation of omega-oxidated products (20-OH and 20-COOH-LTB4) and a novel unpolar metabolite, as identified by thin layer chromatography. This metabolite was not immunoreactive in the LTB4-RIA used. LTC4 and LTD4 were converted into LTE4 when added either to sonicated cells or to the cell-free supernatants of prestimulated tonsillar cells, indicating the release of gamma-glutamyltranspeptidase and dipeptidase, respectively. Our data clearly demonstrate the generation and metabolism of the 5-lipoxygenase products LTB4 and LTC4 as well as the release of histamine from human dispersed tonsillar cells, suggesting that they have a modulatory function with respect to the inflammatory potential at local sites.