NK cells and transplantation

There are different views in the literature on the role of natural killer (NK) cells in the context of solid organ transplantation, as these innate immune cells, similar to T lymphocytes, can have both effector and regulatory functions depending on the subpopulation. Human NK cells belong to the "innate lymphoid cells" (ILCs) and can be divided into CD16+CD56dim and CD16-CD56bright NK cells based on their surface markers, with CD16+CD56dim NK cells representing the main population in the blood with approx. 90% of NK cells. In contrast, the CD16-CD56bright NK cell population is found almost exclusively in lymph nodes, tonsils or liver. Since the lung represents a leukocyte-rich organ, we are mainly interested in lung NK cells, but also in the comparison to cytotoxic CD8+ T cells and CD4+ T helper cells in this special interface organ. With our immunomonitoring studies (in cooperation Prof. Dr. Warnecke, Dr. B. Wiegmann), we were able to show that the human lung contains a very specific repertoire of NK cells that differs significantly both in terms of the expression of typical NK cell surface markers and in the function of NK cells in peripheral blood and other tissues. Since we can also demonstrate that both NK and T cells migrate from the donor lung to the periphery of the recipient directly after transplantation, we are currently primarily interested in their connection to the lung NK and T cell repertoire. The clinical relevance of this transient chimerism in the recipient's blood after lung transplantation is also the focus of our interest.