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.