The long-lasting state of specific nonresponsiveness induced by intravenous immunization with alloantigens is due to the generation of recirculating suppressor T cells.

We investigated whether the long-lasting state of nonresponsiveness that is induced by intravenous immunization with alloantigens is mediated by suppressor T cells, or is caused by inactivation or deletion of the relevant alloreactive T cell clones. The data from parabiosis and thoracic duct drainage experiments suggest that the state of nonresponsiveness depends on recirculating non-proliferating Ts memory cells.