Monoclonal anti-Thy-1.2 antibody induced hematopoiesis in vivo.
The intravenous injection of a monoclonal anti-Thy-1.2 alloantibody (IgM class) induced a rapid increase in the number, and the ratio, of multipotent hematopoietic stem cells (CFU-S) in S-phase. The onset of hematopoiesis was thymus-independent. Reconstitution of lethally-irradiated mice with bone marrow cells from mice injected with antibody augmented the T-cell responsiveness to mitogens. No activation was observed in granulocyte/macrophage progenitors. The monoclonal antibody did not directly stimulate CFU-S in vitro, although hematopoietic activity could be found in the sera of antibody-injected mice. Immediately after injection, the antibody was found bound on Thy-1+ cells in spleen. No decrease in the number of peripheral T cells was seen. These results seem to indicate that Thy-1.2-positive cells bound with anti-Thy-1.2 alloantibody may secrete a factor which induces the proliferation of hematopoietic stem cells.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000145:classification; D000954:Antigens, Surface / Q000276:immunology*; D016026:Bone Marrow Transplantation; D002455:Cell Division; D006098:Granulocytes / Q000502:physiology; D006133:Growth Substances / Q000032:analysis; D006410:Hematopoiesis; D016298:Hematopoietic Cell Growth Factors; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D007075:Immunoglobulin M / Q000008:administration & dosage; D007275:Injections, Intravenous; D007518:Isoantibodies / Q000008:administration & dosage* / Q000145:classification; D007958:Leukocyte Count; D008264:Macrophages / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D011828:Radiation Chimera; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology / Q000528:radiation effects; D018800:Thy-1 Antigens; D013950:Thymus Gland / Q000502:physiology
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D006133:Growth Substances; D016298:Hematopoietic Cell Growth Factors; D007075:Immunoglobulin M; D007518:Isoantibodies; D018800:Thy-1 Antigens; C035678:anti-Thy antibody