Megakaryocytopoiesis in bone marrow-derived stromal-hemopoietic cells co-cultures: action of Tamm-Horsfall glycoprotein

Murine bone marrow cells are cultured in agar in the presence of marrow-derived fibroblasts and pokeweed-stimulated spleen conditioned medium. Granulo-monocytic colonies and a few megakaryocytic and mixed colonies are induced. The addition of Tamm-Horsfall glycoprotein - a human glycoprotein produced in the kidneys - increases the number of colonies and stimulates megakaryocytopoiesis. The glycoprotein does not have colony-stimulating activity nor does it induce megakaryocytopoiesis in monolayer cultures. Its major glycopeptide retains the ability to increase the number of colonies, but not to induce megakaryocytopoiesis. Cell-cell interactions occurring in the hemopoietic microenvironment and the effect of glucides are discussed.