Sir William Dunn School of Pathology, University of
Oxford, South Parks Road, Oxford OX1
3RE, UK. anton.vandermerwe@path.ox.ac.uk
T cell activation usually requires TCR engagement by antigen and
another, costimulatory, signal. Modeling studies now indicate that this second
signal may only slightly enhance TCR signaling, but nevertheless results in
an exponential increase in cell numbers.
