T-CELL UNRESPONSIVENESS CORRELATES WITH QUANTITATIVE TCR LEVELS IN A TRANSGENIC MODEL

Two lines of transgenic mice were developed which differ in their level of expression of V(beta)11. To determine the role of TCR density in tolerance induction, these mice were bred with I-E expressing mice and were investigated for tolerance induction. T cells expressing V(beta)11 at high density are deleted by negative selection. T cells expressing < 10% of the normal TCR receptor density are not subject to negative selection and were not activated in vitro. There is a correlation in receptor density in both strains of mice with in vitro activation. These findings support the notion that there is a definable quantitative signal threshold which is critical for tolerance induction.