The immune system provides the defense for an organism to repel invasion by disease-causing agents. Immunology is the study of all aspects of the immune system in states of both health and disease; malfunctions of the immune system in disorders, such as autoimmune diseases. Researchers in the Department of Pathology study many aspects of immunology including the signalling mechanisms and cell types that generate immune responses, the evolution and function of families of genes integral to the immune system and the process of auto-immunity (in which the immune system attacks the normal tissue of the body).