Clonal Selection
The immune system can detect and trigger a response to an antigens that have not been encountered before.The immune system is based on clonal diversification i.e. the creation of T and B lymphocytes that have the potential for all receptors to antigens.The lymphoid stem cells go through a process of proliferation and differentiation, resulting in the creation of immunocompetent T cells in the thymus, and B cells that are immunocompetent in bone the marrow. Every immunocompetent B or T lymphocyte is able to recognize a particular antigen. However, the entire population of lymphocytes with specificities could represent thousands of different foreign antigens.The lymphocytes remain inactive and dormant until contact with foreign antigen.The immune-competent cells are able to are introduced into circulation and meet foreign antigens in secondary lymphoid organs.
