Dynamic changes of B-cell compartments in kidney transplantation: Lack of transitional B cells is associated with allograft rejection

Abstract

B cells play an important role in the immune responses which affect the outcomes of kidney allografts. Dynamic changes of B-cell compartments in clinical kidney transplantation are still poorly understood. B-cell subsets were prospectively monitored using flow cytometry for 1 year in 98 kidney transplant recipients. Data were correlated with immunosuppression and clinical outcomes. An increase in the total population of B lymphocytes was observed during the first week after transplantation. The level of IgMhighCD38highCD24high transitional B cells reduced significantly up until the third month, with partial repopulation in the first year. Lower numbers of transitional B cells in the third month were associated with higher risk of graft rejection. IgM+IgD+CD27- naive B cells did not change within follow-up. IgM+CD27+ nonswitched memory B cells and IgM-CD27+ switched memory B cells increased on post-operative day 7. IgM-CD38highCD27high plasmablasts showed similar kinetics during the first post-transplant year, similar to transitional B cells. In conclusion, sensitized kidney transplant recipients as well as those with either acute or chronic rejection within the first post-transplant year exhibited lower levels of transitional B cells. Therefore, these data further support the hypothesis that transitional B cells have a protective role in kidney transplantation.