Features of KLH-induced suppression in vivo: characterization of two pathways of suppression.

Keyhole limpet hemocyanin (KLH) given at high dose (4 mg ip) in mice induced a state of unresponsiveness related to the activation of suppressor T cells. An early pathway of suppression is observed within the first 24 hr following KLH injection and is characterized by its cyclophosphamide (CPM) sensitivity and by the specificity of its effector phase, at the level of KLH helper T cells. A late pathway of suppression occurs at Day 3 following KLH injection and is characterized by its CPM resistance and the nonspecificity of its effector phase acting at the B-cell level. Indeed the anti-FLu antibody response to FLu Ovalbumin or thymus-independent antigen FLu LPS were found altered when these antigens were given with TNP KLH. These two pathways of suppression were found to last 8 months. These results suggest that KLH can trigger in an independent manner two pathways of suppression characterized by different CPM sensitivity and different target cells.