Changes in the hemopoietic system of mice deficient for tumor necrosis factor or lymphotoxin-α

Hemopoietic and stromal precursor cells were studied in mice deficient for tumor necrosis factor or lymphotoxin-α. In normal hemopoiesis the main characteristics of hemopoiesis in knockout mice did not differ from those in wild-type mice. Implantation of bone marrow cells from mice deficient for tumor necrosis factor onto irradiated sublayer of allong-living bone marrow culture led to a notable increase in the number of mature cells and granulocytic-macrophage precursor cells. This can be due to the fact that tumor necrosis factor inhibits proliferation of hemopoietic precursor cells, while in the absence of this factor precursor cells actively proliferate. On the other hand, cell composition and number of colony-forming units of granulocytes-macrophages are significantly decreased in cultures onto which bone marrow cells from lymphotoxin-α-deficient mice were implanted. This can be explained by impaired expression of adhesion molecules in these animals. In addition, the number of stromal precursor cells was changed in mice deficient by genes of the tumor necrosis factor cluster.