CD45RO+ memory T cells but not CD45RA+ naive T cells can be efficiently activated by remote co-stimulation with B7 |
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Authors: | Van de Veide Hilde; Lorre Katrien; Bakkus Marleen; Thielemans Kris; Ceuppens Jan L; Boer Mark de |
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Institution: | 1 Division of Physiology-Immunology, Medical School of the Vrije Universiteit Brussels B-1090 Brussels, Belgium
2 Division of Clinical Immunology, Department of Internal Medicine and Pathophysiology, University of Leuven B-3000 Leuven, Belgium
3 Department of Immunology Innogenetics NV, B-9052 Ghent, Belgium |
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Abstract: | Co-stimulatory signals are absolutely required for T cell activationafter TCR–MHC-peptide interaction. The most importantco-stimulatory signal known so far is mediated by the interactionof CD28 on T cells with B7 on APC. Here we demonstrate thatthe co-stimulatory signal from the B7 molecule does not necessarilyhave to come from the same cell which presents antigen. Titrationcurves obtained by limiting the amount of anti-CD3 mAb suggeststhat the same amount of TCR–CD3 cross-linking is requiredfor full T cell activation whether B7 is present on the sameor on another cell, but that the kinetics of T cell activationis slower when B7 is present on a separate cell from the primarysignal. Finally and most importantly we also show that CD45RO+memory T cells, but not CD45RA+ naive T cells, can be efficientlyactivated when B7 is expressed on bystander cells. These findingsimply that co-stimulatory activation requirements of B7 aremore stringent for naive than for memory T cells, which couldbe an important mechanism involved in the maintenance of self-tolerance. |
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Keywords: | B7/BB1 CD28 T cell activation |
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