Stimulatory effects of products from inflammatory exudates upon stem cell production.

The present study is based on the hypothesis that a humoral agent produced in inflammatory exudates is transported to the bone marrow where it stimulates CFU-S to differentiate into leukocytic precursors. Inflammatory exudates were produced by the subcutaneous implantation of a sterile acrylic cup filled with bacteria-free Hanks' balanced salt solution (HBSS) into B6D2F1 mice. The cups were removed 24 h later and the cells were separated from the supernatant. Cells collected from individual mice were pooled, as was the supernatant. Thereafter, normal mice received via tail vein either exudate cells, supernatant, plasma from cup-implanted or from normal mice, bone marrow cells or splenic cells from normal animals or HBSS. Another 24 h later bone marrow was removed from all mice and injected into previously lethally irradiated mice or suspended in vitro in agar-supported media. Nine days later the mice were euthanatized, the spleens removed, and colonies (CFU-S) counted. At the same time, colonies (CFU-C) were enumerated from the agar plates. The results clearly indicate that the bone marrow obtained from mice stimulated with either exudate cells or with super-natant or plasma obtained from cup-implanted mice contained a significantly greater number of CFU-S and CFU-C than did any one of the four control groups. These findings appear to substantiate the hypothesis.