Accumulating evidence suggests that murine mast cells should be involved not only in inflammatory responses but in immune tolerance. Reconstitution studies using mast cell-deficient mice transplanted with bone marrow-derived cultured mast cells indicated that mast cell-derived IL-10 should play critical roles in suppression of inflammatory responses, although few studies demonstrated IL-10 release from murine cultured mast cells. We found that IL-3-dependent murine bone marrow-derived cultured mast cells (BMMCs) could produce IL-10 when they were activated by the combination of the antigen and lipopolysaccharide. BMMCs rapidly released IL-6, which was lately followed by IL-10 under this condition. This time lag raised the possibility that activated mast cells should switch from the inflammatory type to the regulatory one. Activation of BMMCs lead to a drastic decrease in mRNA expression of CD39, which is the ectoenzyme involved in degradation of extracellular ATP, and a P2X7 antagonist, A740003, suppressed IL-10 release in activated BMMCs. These findings suggest that ATP should mediate the phenotypic changes of BMMCs in an autocrine manner.

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