Antibody inhibition of suppressor cell induction.

The IJ genetic restrictions of suppressor T (Ts) cells are controlled by H-2-related determinants that are expressed on antigen-presenting cells. This has led to the hypothesis that Ts cells carry receptors for a self H-2-related ligand that is expressed on specialized antigen-presenting cells. We refer to this H-2-related ligand as the IJ interacting molecule. This report evaluates the ability of rabbit antibodies directed against idiotypes on monoclonal anti-IJ antibodies (the latter are presumably reactive with the Ts cell receptor) to bind IJ interacting molecule and to inhibit antigen presentation to Ts cells. Such anti-idiotypic reagents were prepared against T cell-reactive monoclonal anti-IJk and anti-IJd antibodies. The F(ab')2 fragments of these anti-idiotypic reagents blocked Ts cell induction. The inhibition was haplotype specific and mapped to the IJ region. The anti-idiotypic antibodies blocked the generation of Ts1, Ts2, and Ts3 cells. The cellular target of the blocking activity mediated by these anti-idiotypic antibodies is a macrophage. This was shown by using a cloned macrophage hybridoma line for both Ts induction and absorption of antibody activity. The combined data support the concept that macrophages express IJ interacting determinants that are responsible for Ts cell induction.