The effects of antilymphocyte sera on bone marrow allograft rejection.

Prior sensitization can be a problem in successful graft take in bone marrow therapy. Spleen weight and femoral marrow cellularity have been used as indices of successful graft take in lethally irradiated mice receiving bone marrow allografts. Recovery if poor in mice sensitized, at least 6 days before irradiation and bone marrow therapy, to an intraperitoneal injection of allogenic bone marrow cells. Rabbit anti-mouse lymphocyte serum, normal rabbit serum and pig anti-mouse lymphocyte serum but not normal pig serum partially ablate tis immunity when administered 8 and 10 days after sensitization. Normal rabbit serum is, however, ineffective when administratered 26 and 28 days after sensitization whereas rabbit anti-mouse lymphocyte serum completely ablates this immunity. These findings demonstrate the marked radioresistance of the secondary response to bone marrow allografts and further show the effectiveness of antilymphocyte sera in ablating this immunity.