Human autoimmune lymphoproliferative syndrome, a defect in the apoptosis-inducing Fas receptor: a lesson from the mouse model.

The immune response is regulated not only by the proliferation, differentiation, and activation of cells, but also by programmed cell death, called apoptosis. Fas ligand expressed in activated T cells binds to its receptor, Fas, and induces apoptosis in target cells. Two mouse mutations that cause autoimmune disease, lpr (lymphoproliferation) and gld (generalized lymphoproliferative disease), are mutations in Fas and FasL genes, respectively. Human patients showing phenotypes (Canale-Smith syndrome or autoimmune lymphoproliferative syndrome) similar to those in lpr mice also carry mutations in Fas. This is a good example of a case in which the identification of a mouse mutation has led to the understanding of a human disease.