Origin of donor cells in peripheral blood after BN-to-LEW BM plus intestine transplantation. (A) Peripheral blood chimerism in female recipients of male BM plus female intestine or female BM plus male intestine grafts was analyzed by flow cytometry (BN MHC class I) and quantitative real-time Y-chromosome PCR. Results demonstrated that most donor cells in the blood at 7 days after transplantation consisted of passenger leukocytes from intestine allografts. However, intestine graft–derived cells disappear by day 90. In contrast, BM-derived donor cells gradually increased, and almost all donor cells were of infused BM origin at day 90 and day 150; n = 3 to 4 for each group. (B) PCR analysis of PBMCs with primers for SRY at day 150. When female BN intestine and male BN BM were transplanted into female LEW recipients, male DNA band was identified. On the other hand, transplantation of male intestine and female BM resulted in undetectable SRY band in the blood at day 150, while flow cytometry detected 3.9% donor cells, suggesting that macrochimeric donor cells at day 150 were mainly derived from infused donor BM cells. Blot is representative of 2 independent experiments from 3 to 4 rats per group. (C) Real-time PCR analysis for SRY in various female LEW host organs at day 150 after female BN intestine and male BN BM transplantation. Male DNA derived from BN BM was mainly found in graft GALT (PP and MLN), cervical lymph node (CLN), and host spleen (Sp). Very few infused BM-derived cells were found in host heart (Ht), liver (Liv), tongue (Ton), or bone marrow (BM); n = 3 for each group.