Rejection of bone marrow cells by irradiation mice: NK and T cells recognize different antigens

Numerous studies have indicated that rejection of bone marrow cell (BML) grafts by lethally irradiated mice can be attributed to either NK cells or radioresistent T cells. The four hypotheses that could explain the medianism(s) of rejection of BMC grafts by NK cells include: (1) Donor marrow cells recognize alloantigens of the host and activate host NK cells to attack donor stem cells, the 'allogeneic inhibition' concept; (2) NK cells lyse stem cells coated with natural antibodies via ADCC using their Fc receptors for IgG; (3) NK cells survey the cell surface of stem cells for self H-2 antigens and look or decrease of self H-2 triggers killing; and (4) NK cells recognize with specific receptors H-2 linked hemopoietic histocompatibility (Hh) antigens. The date reviewed on this paper let us to conclude that the mechanism of rejection of BMC allografts by NK involves the use of unique receptors of Hh antigens coded for by genes which map to the S/D interval of H-2 and which are not class I determinants. Furthermore radioresistant Lyt-2⁺ T cells recognize H-2 antigen (class I) on H-2 homozygous or heterozygous BMC. In contrast to NK cells which reject BMC allografts after 24 hours T cells can be stimulated to reject BMC graft by day 7 or 8 after immunization. A model for acute rejction of BMC grafts by NK and T cells is presented.