Expansion of CD8⁺CD45RA⁺CD27^- cytotoxic cells is present only in CMV-seropositive B-CLL patients. Both relative (A) and absolute (B) numbers of CD8⁺CD45RA⁺CD27^- cytotoxic T cells are significantly increased in CMV-seropositive B-CLL patients (filled squares) when compared with CMV-seronegative patients (open squares) and CMV-seropositive controls (filled circles; ^*P < .001 and ^**P < .01). CMV-seronegative controls are represented by open circles.