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Phytohaemagglutinin activation of T cells through the sheep red blood cell receptor

Naturevolume 313pages686687 (1985) | Download Citation



Expression of receptors for sheep red blood cells and the ability to proliferate in response to phytohaemagglutinin (PHA) are the traditional properties of human T cells1,2, but the function of the sheep red cell receptor (the T11 antigen) is controversial3,4 and the mechanism of PHA-induced mitogenesis unclear. Mitogenesis involves a complex series of cell-mediated and factor-dependent interactions, but a rise in intracellular free calcium concentration, [Ca2+]i, seems to be an important primary event in T-cell activation5–7. We have now investigated the effects of three monoclonal antibodies, previously shown to inhibit mitogen-induced proliferation3,8,9, on T-cell [Ca2+]i. We find that anti-LFA-2 and OKT11, which react with the sheep red cell receptor8,10, have no effect on [Ca2+]i, nor do they inhibit the rise in [Ca2+]i induced by concanavalin A (Con A) or the mitogenic anti-T3 monoclonal antibody UCHT1 (ref. 11). They do, however, block PHA-induced Ca2+ mobilization. Anti-LFA-1, which reacts with the lymphocyte function-associated antigen8,12, has no effect on intracellular Ca2+. These studies suggest that the sheep red blood cell receptor is an activation pathway for T cells and that the effects of PHA are mediated through this pathway.


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  1. Department of Haematology, University College Medical School, 98 Chenies Mews, London, WC1E 6HX, UK

    • Kieran O'Flynn
    •  & David C. Linch
  2. Department of Paediatric Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, Massachusetts, 02115, USA

    • Alan M. Krensky
    •  & Steven J. Burakoff
  3. Imperial Cancer Research Fund, Human Tumour Immunology Group, University College Medical School, University Street, London, WC1, UK

    • Peter C. L. Beverley


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