Relative seroprevalence of human herpes viruses in patients with chronic lymphocytic leukaemia

Background Herpes virus infections may have a significant role in chronic lymphocytic leukaemia (CLL) due to their ability to modulate the host’s immune system. Materials and methods We examined the seroprevalence of four herpes viruses [Cytomegalovirus (CMV), Epstein–Barr Virus (EBV), human herpes virus (HHV)‐6 and ‐7] in a cohort of European CLL patients (cohort 1, n = 100) in relation to the immunoglobulin variable heavy (IGHV) chain gene use and compared serological results with those obtained from age‐ and gender‐matched healthy adults (n = 100). Results CMV‐seroprevalence was significantly higher in CLL cohort 1 (79%) than in the control cohort (57%, P = 0·001); the seroprevalence of EBV (89% vs. 94%), HHV‐6 (73% vs. 60%), or HHV‐7 (35% vs. 35%) was not. In CLL cohort 1, use of IGHV3‐30 was more prevalent among CMV‐seropositive and of IGHV3‐21 among HHV‐7‐seronegative cases. To investigate the generalizability of these findings, we investigated the herpes virus seroprevalence in a second cohort of age‐matched CLL patients from a different geographical area (USA, n = 100, cohort 2). In cohort 2, CMV‐seroprevalence was comparable with that of the control cohort (53%). Seroprevalence of EBV, HHV‐6 and HHV‐7 were 85%, 88% and 73% respectively. In CLL cohort 2, use of IGHV3‐30 or IGHV3‐21 was not associated with any of the herpes viruses investigated. Conclusions CMV‐seropositivity is associated with CLL in selected patient cohorts. However, the considerable variation in herpes virus‐specific seropositivity between geographically distinct CLL cohorts indicates that seropositivity for any of the four human herpes viruses investigated is not generally associated with CLL.