T Lymphocytes

T-cells originate from stem cells in the bone marrow. The T-cell precursor rearranges its T-cell receptor genes in the thymus. Immature T-cells that recognise self MHC then receive a signal for survival and cells that interact with cell antigens are swiftly removed and destroyed, this process is known as positive and negative selection in the thymus. Mature T-cells are then able to encounter foreign organisms antigens in peripheral lymphoid organisms where the cells are then activated where they then proliferate and destroy any invader.