title: B Lymphocyte Regulation of Proliferation and Differentiation of Hematopoietic Stem Cells.
abstract: The fraction of bone marrow hematopoietic stem cells was isolated. To induce in vivo proliferation and differentiation of the hematopoietic fraction the helper action of B cells or T cell precursors was necessary. In presence of bone marrow T cell precursors, B cells suppressed spleen colony formation. The intensity of B cell helper or suppressive action depended on their organ localization. Bone marrow B cells were characterized with maximum helper and minimum suppressive activity. On the contrary, spleen B cells exhibited maximum suppressive action on hematopoietic stem cells without helper one. Lymph node B cells possessed intermediate activity compared to those from bone marrow and spleen. The induction of the colony formation was observed in the presence of either naive or activated B lymphocytes. In case of activated B lymphocytes the regulation of hematopoietic stem cells depended on the admixtured cells as Thy-1(+) and SC-1(+) cells, on the presence of precursors of T cells in transplant and on the organ localization of B cells, as well as on the type of the agent for B cell activation. The activation of B cells might resulted in their helper action changed into suppressive or vice-versa. The B cell regulation of hematopoietic stem cell was mediated by their soluble products of non-immunoglobulin nature. It was found, that helper and suppressive factors from B cell hybridoma supernatants regulated hematopoietic stem cells similar to B cells, of which the hybridomas were created. Thus, we attempted to work out the biotechnological basis for obtaining and researching the regulatory products secreted by B cells.
authors.affiliation: Institute of Immunology, Ministry of Public Health, Moscow, Russia.
authors.forename: V. M.
authors.initials: VM
authors.lastname: Manko