CD160 protein and transcript expression is restricted to CLL and HCL. (A) MFI of CD160 in normal B cells. Stem cells were isolated from normal HSC donors. Hematogones and pre-B cells were analyzed from BM samples. (B) MFI of malignant B cells demonstrating significantly increased expression in CLL and HCL. “Non-CLL” represents all B-LPDs excluding CLL and HCL cases. All tissue fields include lymph nodes, spleen, BM, and tonsillar material. Non-CLL tissue includes pre-B-ALL BM samples. *P < .0001; **P < .0001; ***P = .0114. (C-H) Representative flow cytometric images of normal PBMCs (C), pre-B ALL (D), follicular lymphoma (E), MCL (F), CLL (G), and HCL (H). Below each flow cytometric plot is the corresponding cDNA amplification using specific primers for CD160 after reverse transcription of total RNA extracted from highly purified CD19⁺ B cells (isolated using a magnetic-activated cell sorter; purity > 97%). β-actin cDNA synthesis was used as an internal control.