Study of B-cell subpopulations in lung transplant recipients with posttransplant infection.

Posttransplant infection after lung transplantation is a common feature due to the immunodeficiency induced by the immunosuppressive load. To assess B-cell subsets in lung transplant recipients suffering at least one episode of infection within the first year posttransplantation. Twenty-eight lung transplant recipients were enrolled in the study. Their overall mean age was 56.6 ± 10.7 years and 10 were women (35.7%). All recipients were treated with steroids, tacrolimus, and mycophenolate mofetil. B-cell subset levels were measured in peripheral blood before as well as 7, 14, 30, 60, 90, and 180 days posttransplantation. No difference in the absolute number of B-cell subsets was observed within the first year of follow-up. However, pre-germinal center-activated naïve B cells (Bm2'), defined as IgD(+)CD38(++), were increased among patients displaying infections within the first year. The increased Bm2' subset was accompanied by a decrease in the double negative (CD27(-)IgD(-)) B-cell population. Infections in lung transplant recipients were associated with an increase in the Bm2' subset even before transplantation. It is possible that Bm2' cells have a role in response to infection in lung transplantation.