ABSTRACT
The physiological function of T cells comprises tolerance to self-antigens and to those present in diet and microbiota, while antigens in malignant cells are identified and destroyed. T cells, in collaboration with an extensive network of other cells, destroy foreign antigens (pathogens). During the aging process, alterations occur in T cells. This process, named immunosenescence, causes decreased effectiveness in combating pathogens and tumors, response to vaccination, and an increased incidence of autoimmune disease. This chapter will discuss T cells, their function, changes occurring during the aging process, and how T cells replenish the immune system after hematopoietic stem cell transplant (HSCT).
