Those cells that remember the attack strategy of the bacterium and develop resistance when the attack of that bacterium occurs later are called memory cells or memory cells.
Memory cells are long-lived lymphocytes. It is of two types. T-lymphocytes and B-lymphocytes. T-lymphocyte cells are produced in the bone marrow and spread throughout the body via the blood or lymph. They activate the body’s immune system and directly attack disease-causing viruses and bacteria. B-lymphocyte cells produce plasma cells through repeated division. Plasma cells make antibodies. These antibodies inactivate or kill the bacteria.
When the disease first occurs, the memory cells cannot develop any resistance against the germs. Because the memory cells do not contain any antibodies against the antigens of the bacteria. During this time the memory cells contain the process of antigen recognition. These cells work as memory cells in the body. Then the cell divides in the process of mitosis to form a colony. Later, when germs enter the body, the memory cells identify and destroy the germs.