Renal tubular epithelial cells (TEC) can express MHC class II molecules in vitro and in vivo. Their ability to also secrete cytokines and express adhesion molecules suggests a possible immune accessory role for TEC. We have previously documented that TEC process and present antigen to T cell hybridomas. However, engagement of the T cell receptor alone is sufficient to induce IL-2 secretion by T cell hybridomas. We now report that presentation of antigen by TEC to a CD4+ T cell clone results in functional inactivation of the T cells. Despite antigen-specific anergy, these T cells are viable and proliferate in response to IL-2. Furthermore, allogeneic antigen presenting cells were unable to restore the T cell proliferative response, suggesting that the mechanism(s) was not entirely costimulator-dependent.