“…[32][33][34][35][36][37][38] Although the freshly isolated AA4 Ϫ /BGD6 ϩ mast cells do contain mRNA for the ␣ and  subunits of Fc⑀RI, the receptor is not expressed on the surface of the freshly isolated cells, consistent with earlier reports on Fc⑀RI expression in rodent bone marrowderived mast cell cultures. 23,29,39,40 However, after time in culture the AA4 Ϫ /BGD6 ϩ mast cells do express Fc⑀RI, bind IgE, can be activated through Fc⑀RI, exhibit the mast cell-specific gangliosides on their surface, as well as contain metachromatic granules. Morphologic studies of rat bone marrow-derived mast cells have shown that the gangliosides recognized by mAb-AA4 are present only on the surface of granulated mast cells.…”