Cell-surface expression of the FcɛRI in HML-1 cells. (A) The cell-surface expression of the FcɛRI  chain in HML-1 cells was analyzed by flow cytometry. Untreated cells were incubated with mouse MoAb to human CD61 and human FcɛRI  chain, respectively, stained with the FITC-labeled rabbit antimouse IgG + IgM. Mouse IgG1 or IgG2b (for CRA1) were used as isotype-matched control antibodies. (B) Intracytoplasmic expression of the FcɛRI in HML-1 cells was analyzed by flow cytometry after pretreatment of the cells with cold ethanol before incubation with primary or secondary antibodies.