[Relation between Ia antigens and Ir gene products. A theory on the development of the immune response].

To explain the relations between Ia and Ir, we propose the following hypothesis. It would exist an antigen specific factor released by T lymphocytes. This factor would be constituted by two parts: a variable fragment forming the antigenic receptor of T cells and coded by Ir genes, a constant fragment transmitting a helper or suppressor signal and carrying Ia antigens. Ia antigens would allow a mutual recognition between macrophages, T lymphocytes and B lymphocytes and a recognition by these cells of some mediators released during immune response. Ir genes products would allow the antigen recognition, if they correspond to the antigenic receptor of T lymphocytes.