Characterization of the anti-stem cell activity of anti-mouse brain serum.

The anti-stem cell activity of a high-titer rabbit anti-mouse brain serum preparation has been further characterized. Following absorption with bone marrow and erythrocytes the antiserum had dose-dependent cytotoxicity against pluripotent stem cells. Rigorous absorptions with bone marrow, spleen, liver, erythrocytes, and thymus failed to remove the anti-stem cell activity of the serum. Adult brain, the immunogen, but not neonatal brain, removed a substantial amount of the activity against stem cells. Maximal cytotoxicity occurred both with and without complement and was maximal following only a 4 degrees C incubation of cells with serum. The anti-stem cell activity was present in the serum globulin fraction. No increase in the frequency of microcolonies or, with longer growth periods, in splenic macrocolonies was observed, suggesting that CFU-s were completely inactivated by exposure to the antiserum. Injected antiserum also reduced CFU-s in vivo.