CD14 high CD16 + monocytes are the main producers of Interleukin-10 following clinical heart transplantation.

We demonstrate that intermediate monocytes (CD14CD16), but not CD8 T cells, CD4 T cells, CD56 NK cells or CD20 B cells appeared to be the major IL-10 producers within patients PBMC following heart transplantation. Consequently, the absolute monocyte count and the ratio of intermediate monocytes to classical monocytes (CD14CD16) were specifically increased in comparison to pre transplant levels. Hence, this population of monocytes, which has not been in the focus of heart transplantation so far, may be an important modulator of clinical outcome and long-term survival of heart transplant recipients. Alteration of blood-circulating monocytes towards a CD14CD16 phenotype could therefore shift the pro-inflammatory immune response towards induction of graft tolerance, and may pave the way for the optimization of immunosuppression.