Your immune system protects you from viruses, bacteria, and other pathogens, and I am interested in how the cells of the immune system develop. In particular, I am interested in how T cells develop. T cells control the behavior of many other cells in the immune system, and they also kill cells that are infected with viruses. T cells learn to recognize and destroy viruses and other pathogens, but T cells do not generally recognize and destroy normal tissues. Sometimes, however, this process goes awry, and T cells do destroy normal tissues - causing such autoimmune diseases as rheumatoid arthritis, multiple sclerosis, and juvenile diabetes. One of the ways this process can go wrong is in the early life of a T cell when it is still maturing. Therefore, I study the cellular biology and biochemistry that is involved in T cell maturation. By understanding how these processes work, I hope to better understand how autoimmune disease occurs.