Histamine release from fawn-hooded rat mast cells is not potentiated by phosphatidylserine.

Histamine release from the peritoneal mast cells of the Fawn-hooded rat strain is not potentiated by phosphatidylserine (PS) or lysophosphatidylserine (Lyso-PS). When compared with Wistar rats the Fawn-hooded rats produce normal levels of IgE. Except for not being potentiated, the mast cells of Fawn-hooded rats release histamine similarly to Wistar rats when challenged with a variety of IgE and non-IgE mediated inducing agents. Mast cells of Fawn-hooded rats, however, do not respond significantly to dextran challenge which is not improved by PS of Lyso-PS. In the absence of PS the Ca2+ dependence of release from the Fawn-hooded mast cells is similar to the Wistar strain and both are similarly altered in their Ca2+ dependence by the presence of PS; with PS the mast cells of both rat strains release maximum percentages of histamine at levels of Ca2+ which are inhibitory in the absence of PS. The kinetics of release is similar in the two strains. However, when the mast cells are challenged with inducing agent in the absence of Ca2+ the rate of desensitization is slowed by PS in the Wistar strain but not the Fawn-hooded strain.