Plasma Haptoglobin Levels and Radiation Chimeras in Mice

When irradiated mice were grafted with allogeneic bone marrow, their plasma haptoglobin (Hp) significantly increased 2 weeks after grafting. To elucidate the generation of the increase of Hp in allogeneic bone marrow recipients, the relationship between the Hp levels and allograft reactions was assessed. The Hp levels of irradiated recipients, which were inoculated with allogeneic spleen cells, increased with the increase of alloantigen-sensitive units in donor cells. The positive correlation between the Hp levels and graft-versus-host reactions evaluated by spleen weight assay was also observed in unirradiated F₁ hybrid mice which received parental spleen cells. It is, therefore, suspected that the elevated Hp levels found in allogeneic-bone-marrow recipients are associated with lymphoid cell proliferation initiated by alloantigenic stimulations, and it was concluded that Hp levels in allogeneic-bone-marrow recipients provide an indicator of the degree of allograft reactions.