Final answer:
Antibodies are the primary defense mechanism against cellular antigens, triggering type II hypersensitivity reactions and activating the complement system to destroy foreign or mismatched red blood cells.
Step-by-step explanation:
Antibodies are the chief ammunition used against cellular antigens such as bacteria and mismatched red blood cells. Proteins called antibodies or immunoglobulins are produced by B lymphocytes and are pivotal in the immune system's ability to recognize and neutralize foreign objects. These antibodies bind to antigens on the surface of invading pathogens or mismatched red blood cells, promoting type II hypersensitivity reactions. This immune response can lead to the destruction of red blood cells through processes like the activation of the complement system, which is a part of the body's innate immunity and can exacerbate issues such as during transfusion reactions or hemolytic disease of the newborn (erythroblastosis fetalis).