Antigenic Stimulation of DNA Synthesis in the Haematopoietic Stem Cells of Axenic Mice

Abstract

SINCE the work of Becker and McCulloch^1,2 it has been known that a large proportion of the bone marrow stem cells or colony forming units (c.f.u.) of mice is quiescent and a smaller fraction is in the phase of DNA synthesis (S phase). The rate of proliferation of c.f.u. increases in various circumstances, such as stimulation by erythropoietin³, foreign plasma, endotoxin, and bleeding⁴. In our line of C3H holoxenic mice, 25 per cent of the stem cells synthesize DNA. We have noted that during an outbreak of a presumably infectious disease in our animal quarters the number of c.f.u. in synthesis was greater than is usually found in healthy mice. It therefore seemed interesting to find out to what extent the state of proliferation of the c.f.u. is influenced by the presence of micro-organisms and the consequences of their presence. The population of c.f.u. in the bone marrow of axenic mice can be used as an experimental model.