Elimination of self-tolerogen turns nonresponder mice into responders

Two sets of genes control the immune response ofH-2 ^d mice to the synthetic antigen poly(Glu⁵⁰Tyr⁵⁰) (GT). One set involves class II major histocompatibility complex (Mhc) loci encoding an A^d product that serves as a recognition context to GT-reactive helper T cells (T_h). The other one is a background gene, the product of which, in association with the same Mhc-restricting element, mimics the GT/A^d complex. Mice expressing the GT-mimicking background-encoded structure (Im^gt), which is preferentially displayed on B lymphoblasts, do not respond to GT as a consequence of self-tolerance. On the other hand, elimination of cells bearing Im^gt renders these mice responsive to GT, demonstrating that tolerance to self can impoverish the immune system. Im^gt is probably not identical to GT, but resembles it in the way it forms complexes with A^d molecules ofMhc.