Infections after CD34-Selected or Unmanipulated Autologous Hematopoietic Stem Cell Transplantation.

Relapse remains the major cause of failure after high-dose chemotherapy and autologous peripheral blood stem cell transplantation (PBSCT). As tumor contamination of the graft may contribute to this, CD34 selection has been used as an attempt to decrease the relapse rate. However, immune reconstitution may be delayed with CD34 selection due to the removal of T cells, natural killer (NK) cells and monocytes. The result could be an increased incidence of infectious complications. Some small series of patients have reported a higher incidence of infections, and in particular of viral infections, but others have not. Therefore, we compared the incidence of infection in 25 recipients of CD34-selected PBSC (CD34 group) and 75 case-matched recipients of unmanipulated PBSC (PBSC group) transplants. There were 52 males and 48 females with an average age of 52±11 yrs. They included 32 patients with non-Hodgkin’s lymphoma, 8 with Hodgkin’s disease, 40 with multiple myeloma and 20 with breast cancer, with 42 in first-line therapy and 58 in relapse, receiving their 1^st (N=63) or 2^nd (N=37) transplant. The number of CD34 cells infused as well as speed of engraftment were comparable in the two groups. There were no significant increase in the CD34 compared to the PBSC group for: actuarial incidence of infection (56 vs 49% at day 30, 70 vs 64% at 1 yr); proportion of patients with at least 1 (68 vs 68%), 2 (24 vs 17%) or 3 (0 vs 3%) infections; number of infectious events per patient before (1.32 vs 1.04) or after (0.59 vs 0.71) disease progression, before day 30 (0.84 vs 0.64), within days 31–100 (0.00 vs 0.09, p<0.01) or after day 100 (0.48 vs 0.31); risk of VZV (27 vs 30% at 5 yr) or CMV infection (8 vs 6%) or disease (0 vs 3%); use of antibiotics (8 vs 5 days) or antifungal therapy (0 vs 0%) or days with fever (1 vs 1 day) in the initial hospitalisation. However, bacteremias tended to be more frequent in the CD34 group (0.44 vs 0.20 episode/patient). Bacteria accounted for the majority of infections in both groups (64 vs 72%). Infection was the main or a contributing cause of death in 0% and 20% of patients in the CD34 group compared to 1% and 10% in the PBSC group (NS). In conclusion, our results indicate only a trend towards an increased risk of infection after CD34-selected autologous PBSCT. The role of extended infection prophylaxis should be evaluated.