In vitro inhibition of naive alloresponses by the addition of tolerized cells.

The addition of tolerized cells down-regulates a naive alloresponse in vitro. MLR culture consisted of 10⁵ naive B6 CD4⁺ T-cell responders per well and 10⁵ bm12 splenic stimulators per well plated with and without B6 CD4⁺ T cells (3 × 10⁴ per well) that had previously been tolerized to bm12 alloantigen by a 10-day culture with anti-CD40L mAb. Tolerized cells were washed free of Ab and cytokines prior to plating in regulatory cultures. The y-axis presents the mean cpm ± 1 SE. On the x-axis are days in primary culture. One of 5 representative experiments is shown.