Rapid rejection of H2k and H2k/b bone marrow cell grafts by CD8+ T cells and NK cells in irradiated mice.

Acute rejection of transplanted bone marrow cell (BMC) grafts can occur within 48 h in unsensitized, lethally irradiated mice, and NK cells have been implicated as the effector cells. Recently, we observed that both CD8+ TCR-alpha beta+ T and NK cells of irradiated mice could rapidly reject allogeneic lymph node cell grafts. In this study, we evaluated the ability of NK and CD8+ T cells to mediate rejection of H2k or H2k/b BMC grafts by pretreating groups of mice with depleting mAbs. H2k BMC were transplanted into syngeneic, B6 (H2b), BALB/c (H2d), NZB (H2d), and (NZB x B6)F1 (NZB6F1, H2d/b) hosts. Proliferation measured 5 days after cell transfer indicated that syngeneic, B6, and BALB/c hosts accepted H2k BMC grafts. However, CD8+ T cells from NZB and poly I:C-treated BALB/c hosts, and NK cells from poly I:C-treated NZB6F1, hosts, rejected H2k BMC grafts. In NZB6F1 hosts, there was an added effect of anti-TCR-alpha beta and anti-NK1.1 mAbs. It is possible that T and NK cells cooperate in rejecting H2k or H2k/b BMC grafts in certain hosts. Transplantation of H2k/b, but not H2k/d, BMC into similar recipients had the same fate as H2k BMC. Thus, certain CD8+ T cells may share a similar recognition system with NK cells.