Lysophosphatidylserine-induced activation of mast cells in mice

Intravenous injection of lysophosphatidylserine (2.5-25 mg/kg) increases the blood histamine level in mice. Lysophosphatidyl-D-serine, alkyl-lysophosphatidylserine and glycerophosphorylserine show little or no activity. As shown by the similar efficacy of the analogue lacking the OH group in the C-2 position of glycerol conversion into phosphatidylserine is not required. The age of mice influences the activity of lysophosphatidylserine. Thus, the increase in blood histamine is greater in adult mice (8-10 weeks) than in young mice (4-6 weeks). In old mice (50-60 weeks) the tolerance to lysophosphatidylserine is reduced. Repeated parenteral administrations induce depletion of histamine stores with concomitant desensitization to lysophosphatidylserine. Well-perfused organs containing connective tissue mast cells (tongue) are more affected. When [3H] histidine is injected into lysophosphatidylserine-treated mice, the highly radioactive histamine detected in the tongue indicates the preservation of histidine decarboxylase activity after degranulation. The data suggest that lysophosphatidylserine specifically activates connective tissue mast cells in mice.