Different kinetics of donor cell populations after isolated liver and combined liver/small bowel transplantation

Abstract Spontaneous tolerance induction after liver transplantation also supports additional transplants, e. g. a small bowel graft, from the same donor (tolerogenic effect). Chimerism serves as a possible explanation of this phenomenon. Isolated liver (LTx) and combined liver/small bowel transplantation (LSBTx) are compared. LSBTx and LTx were performed in the BN → LEW rat strain combination without immunosuppression. Parenchymal damage during rejection was monitored by sequential standard histology. Donor/recipient populations were identified and further differentiated for immunhistochemical single and double staining. A small number of donor specific leukocytes can be detected on all days in host organs (microchimerism). A significantly larger donor leukocyte population survives long‐term in the sinusoids of liver (graft chimerism). Sinusoidal donor leukocytes survive rejection and recover in number after tolerance induction. Rejection of liver allografts and infiltration by host leukocytes are more pronounced after LSBTx than after LTx. Accordingly, during rejection a steeper decline of sinusoidal donor leukocytes is observed after LSBTx and recovery after tolerance induction is not as marked. Microchimerism apparently plays no significant role in either transplantation model. The number of sinusoidal donor leukocytes, however, mirrors closely host immune responses.