title: Mixed chimerism, heart, and skin allograft tolerance in cyclophosphamide-induced tolerance.
abstract: We elucidated the possible role of chimerism in skin and heart allograft tolerance using cyclophosphamide (CP)-induced tolerance. When C3H (H-2k; Thy1.2, Mls-1b) mice were i.v. primed with 1x10(8) spleen cells (SC) from H-2 matched AKR (H-2k; Thy1.1, Mls-1a) mice and then treated i.p. with 200 mg/kg of CP, the survivals of both AKR skin grafts and heart grafts (HG) were permanently prolonged in a tolerogen-specific fashion. After this treatment, a minimal degree of mixed chimerism, the clonal destruction of Mls-1a-reactive CD4+Vbeta6+ T cells in the periphery, and the clonal deletion of Vbeta6+ thymocytes were all observed. When AKR SC and 100 mg/kg CP were used for conditioning, the AKR HG were permanently accepted, but the survival of the AKR skin grafts was only mildly prolonged. The clonal destruction of CD4+Vbeta6+ T cells in the periphery and the intrathymic clonal deletion of Vbeta6+ thymocytes were induced in both the SC and the 100 mg/kg CP-treated C3H mice. A minimal degree of mixed chimerism was detectable at 4 and 12 weeks after AKR SC and 100 mg/kg CP treatment, and still did not disappear at 40 weeks. The degree of mixed chimerism induced with SC and 100 mg/kg CP was significantly lower than that with SC and 200 mg/kg CP during the observation. No posttransplant cardiac allograft vasculopathy (CAV) was observed to develop, while both the Th1 type (interferon-gamma) and Th2 type (interleukin-4 and -10) cytokine expressions decreased in the AKR HG of the tolerant C3H mice treated with both AKR SC plus 200 mg/kg CP, and AKR SC plus 100 mg/kg CP. A second set of skin grafts from donor AKR mice survived for more than 100 days in a tolerogen-specific fashion in all C3H mice treated with AKR SC and 200 mg/kg CP and also accepted the AKR HG for over 200 days, while 80% of the C3H mice treated with AKR SC and 100 mg/kg CP and accepted the AKR HG for more than 200 days. These results strongly suggested the following conclusions: 1) the degree of chimerism can strongly influence the induction of skin and heart allograft tolerance, 2) posttransplant CAV does not develop in the donor HG maintained by chimerism-based CP-induced tolerance, 3) the mRNA expression of both Th1 and Th2 type cytokine decreased in the donor HG maintained by chimerism-based CP-induced tolerance, and 4) the induction of skin allograft tolerance is more difficult than the prevention of posttransplant CAV.
authors.affiliation: Department of Cardiovascular Surgery, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: Q W
authors.initials: QW
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Tomita
authors.forename: G
authors.initials: G
authors.lastname: Matsuzaki
authors.forename: M
authors.initials: M
authors.lastname: Yoshikawa
authors.forename: I
authors.initials: I
authors.lastname: Shimizu
authors.forename: Y
authors.initials: Y
authors.lastname: Nakashima
authors.forename: K
authors.initials: K
authors.lastname: Sueishi
authors.forename: K
authors.initials: K
authors.lastname: Nomoto
authors.forename: H
authors.initials: H
authors.lastname: Yasui
mesh_terms: D000818:Animals; D000917:Antibody Formation; D017637:Clonal Deletion / Q000187:drug effects; D003520:Cyclophosphamide / Q000494:pharmacology*; D016207:Cytokines / Q000235:genetics; D004247:DNA / Q000235:genetics; D005260:Female; D015870:Gene Expression; D016027:Heart Transplantation / Q000276:immunology*; D007108:Immune Tolerance / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008806:Mice, Inbred AKR; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016038:Skin Transplantation / Q000276:immunology*; D013154:Spleen / Q000166:cytology; D013997:Time Factors; D018183:Transplantation Chimera / Q000276:immunology*
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D003520:Cyclophosphamide; D004247:DNA