Colony-forming activity of pluripotent stem cells in tolerant mice following antigen exposure.

The effect of sheep red blood cells (SRBC) and human red blood cells (HRBC) on the number of CFU-S in the bone marrow and spleen of (CBA X C57BL/6)F1 mice tolerant to SRBC was examined. The number of bone marrow and spleen CFU-S in SRBC tolerant mice was increased after injection of HRBC. After challenge with SRBC, CFU-S number was elevated in the spleen but not in the bone marrow. Thus, the mechanism of CFU-S activation in response to antigen exposure is different in the bone marrow and spleen.