NK Cells Rapidly Reject Allogeneic Bone Marrow in the Spleen Through a Perforin‐ and Ly49D‐Dependent, but NKG2D‐Independent Mechanism

• Published in: American journal of transplantation Vol. 7; no. 8; pp. 1884 - 1896
• Main Authors: Hamby, K., Trexler, A., Pearson, T. C., Larsen, C. P., Rigby, M. R., Kean, L. S.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-08-2007; Blackwell
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Antigens, Ly - immunology; Antigens, Ly - metabolism; Antigens, Surface; Biological and medical sciences; Bone Marrow Cells - immunology; Bone Marrow Cells - pathology; Bone marrow transplant; Bone Marrow Transplantation - immunology; Bone Marrow Transplantation - pathology; Bone marrow, stem cells transplantation. Graft versus host reaction; Chimerism; Connexins - metabolism; Disease Models, Animal; Eye Proteins - metabolism; Flow Cytometry; Graft Rejection - genetics; Graft Rejection - immunology; Graft Rejection - pathology; Immunity, Cellular; Killer Cells, Natural - immunology; Killer Cells, Natural - pathology; Lectins, C-Type - immunology; Lectins, C-Type - metabolism; Lymph Nodes - immunology; Lymph Nodes - pathology; Medical sciences; Membrane Glycoproteins - metabolism; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; NK Cell Lectin-Like Receptor Subfamily A; NK Cell Lectin-Like Receptor Subfamily K; NK cells; Perforin; Pore Forming Cytotoxic Proteins - metabolism; Receptors, Immunologic - metabolism; Receptors, Natural Killer Cell; Receptors, NK Cell Lectin-Like; rejection; Spleen - immunology; Spleen - pathology; Spleen - surgery; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; T-Lymphocytes, Cytotoxic - immunology; T-Lymphocytes, Cytotoxic - pathology; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Transplantation, Homologous; Spleen; Graft(material); NK cells; Cytolysin; NKG2D receptor; Stem cell; Hematopoietic cell; Bone marrow transplantation; Mechanism; Allogeneic system; Natural killer cell; Refusal; Rejection; Bone marrow; Bone marrow transplant; Perforin
• ISSN: 1600-6135; 1600-6143
• DOI: 10.1111/j.1600-6143.2007.01864.x

We have used a sensitive and specific in vivo killing assay to monitor the kinetics, anatomic location and mechanisms controlling NK‐mediated rejection of Balb/c bone marrow by C57BL/6 natural killer (NK) cells. We find that NK killing of fully allogeneic bone marrow is a rapid, highly efficient process, leading to substantial rejection of transplanted marrow within 6 h of transplant and elimination of 85% of the transplanted cells within 2 days. NK‐mediated rejection occurred predominantly in the spleen, with sparing of rejection in the bone marrow and lymph nodes. Rejection was dependent on Perforin gene function, but was independent of interferon‐gamma. Finally, rejection of Balb/c bone marrow by B6 NK cells required signaling through the Ly49D receptor, but occurred despite blockade of NKG2D, which distinguishes these results from previous studies using semiallogeneic transplant pairs. These results identify NK cells as highly active mediators of bone marrow rejection, and suggest that inhibiting NK function early during transplantation may increase the efficiency of engraftment and allow successful engraftment of limiting doses of donor bone marrow.
In both a transplant assay and an in vivo killing assay, murine C57Bl/6 NK cells kill allogeneic Balb/c bone marrow targets rapidly in the spleen, through a perforin‐ and Ly49D‐mediated mechanism, but killing occurs despite blockade of the NKG2D activating receptor.