Final answer:
The secondary immune response to TB antigen occurs when memory cells differentiate into effector cells without the need for other cells of the adaptive immune system. This results in a stronger and faster immune response, producing a greater amount of antibodies that may stop the infection before it becomes established.
Step-by-step explanation:
If the host is re-exposed to the same TB antigen, circulating memory cells will immediately differentiate into effector cells without input from other cells of the adaptive immune system. This is known as the secondary immune response, which is stronger and faster than the primary immune response. Memory B cells will differentiate into plasma cells that produce a greater amount of antibodies compared to the primary response. The rapid and dramatic antibody response may prevent the infection from becoming established.