Thymic cortical epithelial cells lack full capacity for antigen presentation

SEVERAL recent studies have suggested that interactions between thymocytes and thymic stromal cells are essential for the development and elimination of antigen-reactive T lymphocytes^1-4. It is important, therefore, to characterize the stromal cells involved in presentation of antigen in the thymus. In a previous report, we demonstrated, using T-cell hybridomas, that three distinct types of antigen presenting cells in the thymus (cortical epithelial cells, macrophages, and dendritic cells) constitutively expressed self haemoglobin/la complexes⁵. Here we report that one of these cell types, the cortical epithelial cell, does not induce stimulation of T-lymphocyte clones even though the antigen/la complex required for antigen-specific recognition is present. This lack of response occurs with both T_H1 and T_H2 clones. Responsiveness of the T_H2 clone can be restored by adding the murine lymphokine interleukin-1β to the culture system.