A monoclonal antibody to antigens expressed on MLR-activated T cells inhibits granulocyte macrophage colony formation
Bacigalupo, A.; Podesta, M.; Frassoni, F.; Marmont, A.; Risso, M.; Corte, G.
Journal of Immunology 127(6): 2415-2417
1981
ISSN/ISBN: 0022-1767 PMID: 6457875 Document Number: 174264
A monoclonal antibody specifically reactive with MLR-activated T cells (MLR2) was added to light density normal marrow cells, depleted of adherent cells and T lymphocytes, and plated in soft agar for granulocyte macrophage colony formation. Colonies from MLR2-treated marrow cells were reduced to less than 10% of expected growth. The inhibition was not complement dependent, did not require the continuous presence of MLR2 in culture, and could not be detected also when human placenta-conditioned medium was used in the place of leukocyte feeder layers as a source of colony-stimulating factor (CSF). Co-culture experiments with MLR2 treated and untreated marrow cells further excluded the possibility of an indirect effect of MLR2 on CFU-c via auxiliary cells. The results of this study suggest that myeloid progenitor cells express a lymphoid antigen that is absent on resting or activated B cells and on resting T cells, but is expressed on activated T cells.