Indicate true (T) and false (F) statements below regarding lymphocytes in the adaptive immune system. Your answer would be a four-letter string composed of letters T and F only, e.g. TTFF.
( ) To induce an adaptive immune response, an invading pathogen must invade a peripheral lymphoid organ.
( ) Lymphocytes continuously circulate between central and peripheral lymphoid organs.
( ) Upon encountering its specific antigen in a peripheral lymphoid organ, a lymphocyte remains there to proliferate and differentiate into effector and memory cells.
( ) Memory B and T cells do not recirculate, but rather remain in the peripheral lymphoid organ in which they develop.