CD8⁺ DCs, NKT cells, and expression of NKG2D are required for heart allograft survival and development of chimerism after combined BMT and heart transplantation. (A) Experimental scheme: BALB/c or C57BL/6 hosts were given donor C57BL/6 or BALB/c neonatal heart transplants (HTX), respectively, on day 0, and ATS was injected i.p. on days 0, 2, 6, 8, and 10. Hosts were conditioned over 14 days with 10 doses of TLI of 240 cGy each. On day 15, 50 × 10⁶ C57BL/6 or BALB/c donor bone marrow cells from the same strain as the heart grafts were injected IV (bone marrow transplantation [BMT]), and chimerism and heart graft survival were monitored for 100 days after organ transplantation. (B) Percentages of hosts with heart graft survival among wild-type (WT) BALB/c (n = 10), or Batf3^−/− (n = 8), or Jα18^−/− (n = 8) hosts or WT C57BL/6 (n = 10) or NKG2D-deficient (Klrk1^−/−) (n = 8) hosts at serial time points. WT TX (BALB/c) vs Batf3^−/− TX: P < .001; WT TX (BALB/c) vs Jα18^−/− TX: P < .001; WT TX (B6) vs NKG2D-deficient (Klrk1^−/−) TX (B6): P < .001; Batf3^−/− TX vs Jα18^−/− TX: P < .001 (log-rank; Mantel-Cox test). (C) Percentages of donor type cells among (T cells, B cells, macrophages, and granulocytes in the blood of hosts 28 days after BMT. Bars show mean percentages of donor cells. P values by the 2-tailed t test of independent means. *P < .05; **P < .01; ***P < .001; NS, not significant (P > .05).