The requirements for activation of an antigen specific T-cell clone via the CD3 complex

We have studied the requirements for the activation of the haemagglutinin peptide specific cloned T-cell HA1.7 by anti-CD3 antibodies and the mechanism of modulation of the CD3 complex. Cross-linking of the complex either by a soluble antibody second layer or an immobilized matrix of antibody is necessary for induction of a proliferative response. This proliferative response is totally dependent on exogenously added IL-2. Modulation of the cross-linked CD3 complex is by patching, capping and internalization of the antigen and is not essential for the proliferative response.