HISTAMINE-RELEASE FROM RAT MAST-CELLS INDUCED BY PROTAMINE SULFATE - THE MODE OF ACTION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 39  (10) , 1037-1044
Abstract
Protamine sulfate, known for a long time as a histamine releaser, was labeled with a fluorescent dye (FITC [fluorescein isothiocyanate]). This conjugate stained selectively the mast cell fraction of rat peritoneal cells. Within a few seconds, the protamine was found inside the cells. Although the cells had lost their histamine completely, no granules were found outside the cells. In the EM, the protamine treated mast cells showed a loss of the electron density of their granules, a vacuolization and other signs of histamine release. Evidence for a direct connection between the vacuoles and the extracellular fluid was gained by incubating mast cells in FITC-labeled human serum albumin [HSA] followed by the addition of unlabeled protamine. After washing, the fluorescence was found to be located inside the cells, demonstrating an influx of the FITC-HSA under the influence of protamine. The protamine-induced release reaction is increased after addition of Ca2+, reduced by lowering the temperature, addition of 2-deoxyglucose or cytochalasin B. Disodium cromoglycate diminished the histamine release in a dosis dependent manner. Protamine did not induce a loss of lactate dehydrogenase from the mast cells. The release reaction is mediated by the cell membrane, as shown by the releasing activity of insolubilized protamine. The protamine-induced release is a non-cytotoxic reaction, fulfilling some criteria of the anaphylactic histamine release.