T cells are white blood cells, which make up part of the adaptive immune system
T cells recognise foreign structures presented on cells of the own body. To prevent them from recognising self antigens and becoming activated, T cells undergo a negative selection to destroy such cells. This should prevent autoimmune diseases. There are different types of T cells. Some recognise and kill virus-infected cells of the own body. Others activate B cells
, which then initiate the production of antibodies
. They are called T cells as they mature in the thymus.