FcɛRI gene expression in human platelets and HML-1 cells. The FcɛRI gene expression in human platelets (total number: 1 × 10⁸, purity: >99%) and in the human megakaryocyte like cell line, HML-1 cells (total number: 1 × 10⁷) was analyzed by RT-PCR. 1 × 10⁷ human peripheral white blood cells were used as positive control and 1 × 10⁷ of the human erythroleukemic cell line, K562 cells were used as negative control. FcɛRI , β, and γ chain gene segments from 1 μg of each cDNA sample were PCR amplified in the presence of specific sense and antisense primers. Lane 1: human peripheral white blood cells; lane 2: human platelets; lane 3: human megakaryocyte-like cell line, HML-1 cells; lane 4: human erythroleukemic cell line, K562 cells as negative control.