Effect of bone marrow T lymphocytes treated with CAMPATH 1G on megakaryocyte colony formation

V. R. Deutsch*, A. Nagler, S. Slavin, R. Condiotti, R. F. Levine, A. Eldor

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Specific populations of lymphocytes play a significant role in the regulation of megakaryocyte (MK) development. CAMPATH 1G (C1G) and CAMPATH 1M (C1M) are T lymphocyte (TL)-specific monoclonal antibodies (MABs) that are routinely employed to reduce graft-vs.-host disease (GVHD) in allogeneic bone marrow transplantation (BMT). Following BMT, engraftment of the erythroid and myeloid lineages is prompt, but prolonged thrombocytopenia often prevails. We therefore studied the effect on MK colony formation of treating donor bone marrow (BM) with the CAMPATH MABs. MK colonies were grown in plasma clots using postirradiation aplastic canine serum (PICS-J) as MK colony-stimulating factor (MK- CSF). C1M, which causes TL destruction by complement-dependent lysis, had no effect on MK cloning efficiency. C1G is not lytic but causes the elimination of TL in the BMT recipients via antibody-dependent cell cytotoxicity (ADCC). Treatment of donor BM with C1G significantly enhanced the number of early burst-forming units (BFU-MK) and late colony-forming units (CFU-MK) and had no effect on granulocyte-macrophage (CFU-GM) or erythroid (BFU-E) colonies. Enhancement of MK cloning efficiency was concentration-dependent between 0.03 and 3 μg MAB/106 BM mononuclear cells (MNC). Similar results were observed when C1G-treated TL or purified CD4+ TL were co-cultured with untreated autologous BMMNC or peripheral blood (PB) MNC. Conditioned medium (CM) from C1G-treated TL and CD4+ TL contained soluble factors that, when combined with suboptimal doses of PICS-J, potentiated MK growth. C1G in combination with PICS-J also stimulated TL proliferation in a dose-dependent manner. The T cell CM did not contain elevated levels of interleukin-3 (IL-3), IL-6, IL-β, or GM-CSF. Our data provide additional evidence for the involvement of activated TL, and perhaps novel soluble T cell products, in the immunomodulation of megakaryocytopoiesis.

Original languageEnglish
Pages (from-to)1427-1435
Number of pages9
JournalExperimental Hematology
Issue number11
StatePublished - 1993
Externally publishedYes


  • Cytokines
  • Megakaryocytopoiesis
  • T cell activation


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