Beige mouse mast cells generated in vitro: ultrastructural analysis of maturation induced by sodium butyrate and of IgE-mediated, antigen-dependent degranulation

Abstract

We derived growth factor-dependent mast cell lines from C57BL/6-bgJ/bgJ ('beige') mouse bone marrow cells using techniques previously described for deriving mast cell lines from normal mice. According to examination by transmission electron microscopy, the cytoplasmic granules of cultured mast cells derived from beige mice were larger in size and fewer in number than those in cultured mast cells derived from normal C57BL/6 mice. Mast cells derived from beige mice underwent maturation when exposed to sodium butyrate, as judged by increased content of electron-dense material in the cytoplasmic granules. Cultured mast cells derived from beige mice also underwent IgE-mediated, antigen-dependent anaphylactic degranulation which was similar in its ultrastructural features to that described for cultured mast cells from normal mice. However, in mast cells not stimulated with IgE and antigen, fusion between individual cytoplasmic granules was observed more commonly in mast cells derived from beige mice than in normal mast cells. This might mean that these events are more common in C57BL/6-bgJ/bgJ mast cells, and/or that their resolution is slower and thus more easily captured by electron microscopy.