Selective expression of MUC1 in CTCL patients. (A-D) PBMCs from 6 patients with L-CTCL with previously identified unique TCR Vβ rearranged malignant clone and 6 corresponding normal donors were isolated and analyzed for MUC1 and CD4 expression by flow cytometry. Each dot represents an individual patient or control, and results are presented as percentage of cells expressing MUC1 in the CD4⁺ population (A); TCR Vβ expression was analyzed in the CD4⁺ subset of cells (B), and MUC1 expression was further analyzed in the CD4⁺, TCR Vβ⁺ subset of cells (C). Representative FACS plots of a patient with L-CTCL and healthy donor are shown (D).