TY - JOUR AU - Bonilla, Weldy V. AU - Geuking, Markus B. AU - Aichele, Peter AU - Ludewig, Burkhard AU - Hengartner, Hans AU - Zinkernagel, Rolf M. T1 - Microchimerism maintains deletion of the donor cell–specific CD8+ T cell repertoire PY - 2006/01/04/ AB - Rare cases of stable allograft acceptance after discontinuation of immunosuppression are often accompanied by macrochimerism (> 1% donor cells in blood) or microchimerism (< 1% donor cells in blood). Here, we have investigated whether persistence of donor cells is the cause or the consequence of long-lasting CTL unresponsiveness. We found that engraftment of splenocytes bearing a single foreign MHC class I–restricted epitope resulted in lifelong donor cell microchimerism and specific CTL unresponsiveness. This status was reversed in a strictly time- and thymus-dependent fashion when the engrafted cells were experimentally removed. The results presented herein show that microchimerism actively maintains CTL unresponsiveness toward a minor histocompatibility antigen by deleting the specific repertoire and thus excluding dominant, T cell extrinsic mechanisms of CTL unresponsiveness independent of systemically persisting donor cell antigen. JF - The Journal of Clinical Investigation JA - J Clin Invest SN - 0021-9738 DO - 10.1172/JCI26565 VL - 116 IS - 1 UR - https://doi.org/10.1172/JCI26565 SP - 156 EP - 162 PB - The American Society for Clinical Investigation ER -