Protein analysis of TOSO using CLL tissue microarray and quantitative flow cytometry. (A) Immunohistochemistry for TOSO in tissue microarray cores. The entire 1-mm core was analyzed using a Leica DM2500 microscope, and images were acquired by a Leica DFC320 camera and processed using Leica IM50 software (Meyer Instruments, Houston, TX) at low (10×/0.30, HC PL FLUOTAR) and high (40×/0.75, HCX PL FLUOTAR) power objective magnification (OM) in each case, and the consensus of 2 cores was accepted. Results shown demonstrate (i) positive cells in mantle zone of tonsil OM ×10; (ii) positive cells in mantle zone of tonsil OM ×40; (iii) negative CLL sample OM ×10; (iv) negative CLL sample OM ×40; (v) positive CLL sample OM ×10; (vi) positive CLL sample OM ×40. A total of 44 CLL samples were assessed for TOSO. (B) Quantitative flow cytometry demonstrating a shift in TOSO expression in 2 CLL cases (red lines) against a single healthy individual (gray line). (C) Graphic comparison for normalized median fluorescence intensity (nMFI) for TOSO in CLL and nCD19⁺ cells (nMFI = 44.98 ± 18.31 in CLL vs 7.96 ± 11.45 in nCD19⁺ cells, P = .31, Mann-Whitney test). Bars represent the median values.