Expression of the FcɛRI in HML-1 cells. The cell-surface expression of the FcɛRI in HML-1 cells (A) was analyzed, by immunohistochemistry after staining with the antihuman FcɛRI  chain MoAb (CRA1) using the APAAP method. The intracytoplasmic expression of the FcɛRI in HML-1 cells (B) was analyzed, by immunohistochemistry as described above after permeabilization with saponin. Although no immunoreactivity was detected for the FcɛRI  chain on the cell surface of HML-1 cells, FcɛRI  chain expression was clearly detected in the cytoplasm of HML-1 cells.