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Figure 2 | Biology Direct

Figure 2

From: The ability of natural tolerance to be applied to allogeneic tissue: determinants and limits

Figure 2

Natural tolerance to multiple minor internal transplants carrying passenger lymphocytes. (A) Experimental design and timeline. BALB.B heart grafts were given under the kidney capsule of B10-RAG recipients 9 or 1 mos. before (pre-FL) or 1 mos. after (post-FL) they were reconstituted with B6 fetal liver cells. Visual inspection of grafts at 3.5 mos. after FL injection showed all 9 mos. healed grafts (n = 8) were present and beating, while 7 of 8 grafts given post-FL and all those healed only 1 mos. (n = 4) were completely gone (only scar tissue remaining). Some recipients with a 9 mos. healed in graft were immunized with 3 × 106 BALB.B spleen cells 4 mos. after FL injection (n = 3) and others received a second BALB.B heart graft under the capsule of the opposite kidney 4.5 mos. post-FL (n = 4); these second BALB.B cardiac grafts were all present and beating at 3.5 months post transplantation (8 mos. after FL). (B-G) Representative macroscopic and histological (100X) analyses of BALB.B cardiac grafts. (B) Histology of a 9 mos. healed in pre-FL BALB.B cardiac graft under kidney capsule at 3.5 mos. post-FL reconstitution. (C) Histology of the 1 out of 8 post-FL BALB.B heart grafts that had not been completely rejected at 3.5 mos. post-FL cell reconstitution; the graft was not beating. (D) Histology of a 9 mos. healed in pre-FL BALB.B cardiac graft under kidney capsule at 5.5 mos. post-FL cell reconstitution and 5 weeks post immunization with BALB.B spleen cells. (E) Histology of a post-FL BALB.B cardiac graft under kidney capsule at 5.5 mos. post-FL cell reconstitution (only fibrotic tissue remains). (F) Representative appearance of cardiac grafts that are not rejected (beating); a 9 mos. healed in pre-FL BALB.B cardiac graft under kidney capsule (5.5 mos. post-FL cell reconstitution and 5 wks. post immunization with BALB.B spleen cells) is shown. (G) Representative appearance of rejected cardiac grafts; what remains (scar tissue) of a post-FL BALB.B cardiac graft under kidney capsule (5.5 mos. post-FL cell reconstitution) is shown. (H) Staining for donor (Ly9.1+) BALB.B cells in PBL of B10-RAG recipients of a BALB.B heart graft (9 mos. healed; lower histogram) 4 mos. following reconstitution with B6 FL cells and in control B6 and BALB/c mice; at the same time, four color flow cytometry for B and T cells was done (gated on donor (Ly9.1+) vs. host (Ly9.1-) cells) in the heart graft recipients (representative dot plots are shown). (I) Donor specific CTL in individual B10-RAG mice, reconstituted 3.5 mos. previously with B6 FL cells, that had received a BALB.B heart graft 9 mos. pre-FL or post-FL (p < 0.01). In a third group the ability of the long established heart graft to prime CTL was tested by re-transplanting 9 mos. established BALB.B hearts from B10-RAG recipients into B10-RAG mice previously reconstituted with B6 FL (Post-FL, re-tx; p < 0.05 vs. pre-FL).

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