Role of Nominal Antigen and Ia Antigen in the Binding of Antigen-Specific T Lymphocytes to Macrophages

Abstract
We have previously demonstrated that when primed T lymphocytes were repeatedly incubated on monolayers of antigen-pulsed macrophages (Mø), the cells that failed to adhere to the monolayer demonstrated a marked depletion of their proliferative response that was specific both for the antigen used for pulsing the Mø and for Ia determinants on the Mø. In order to further analyze the contribution of the nominal antigen and Ia antigens to the physical binding of T lymphocytes to Mø, we have attempted to block the absorption of T lymphocytes to Mø with a large excess of soluble antigen and with anti-Ia sera. Our results demonstrate that anti-Ia sera inhibit but that soluble antigen augments the binding of specific T lymphocytes to Mø. The implications of these findings for “dual recognition” and “linked recognition” models of T lymphocyte receptors are discussed.