Scanning electron microscopy of RBL-2H3 mast cells co-cultured with P. brasiliensis yeast.

The non-stimulated (NS) RBL-2H3 mast cells are fusiform and their surface is covered with fine microvilli (small arrows). RBL-2H3 cells sensitized with IgE anti-TNP and stimulated for 15 min with DNP₄₈-HSA are spread on the substrate and ruffles are present on the plasma membrane (large black arrows). RBL-2H3 cells co-cultured for 15 min with P. brasiliensis yeast cells (arrowhead) present ruffles (large white arrows) and a morphology similar to stimulated mast cells. By scanning electron microscopy P. brasiliensis yeast cells are multicellular with daughter cells attached by a narrow neck.