White blood cells are the primary protectors of the human body, working against infectious pathogens such as viruses, fungus, and bacteria. B-lymphocytes, one of several kinds of white blood cells, are involved in a specific type of adaptive immunity necessary for the antibody response. During the early stages of development, b-cell production begins in the fetus in the liver and occurs in the bone marrow thereafter.
Immunity is accomplished in two chief ways — either it is innate or acquired, which is also referred to as adaptive immunity. Innate immunity is a non-specific form of defense with which everyone is born, including chemical responses, structures that act as barriers such as the skin and mucus membranes, and the host of microorganisms residing in the body, called the normal flora. Some harmful pathogens are successful in getting past these natural barriers, in which case adaptive immune responses are activated, where b-lymphocytes play a significant role. Humoral immunity is an adaptive mechanism of specific immunity involving the formation of antibodies, which are proteins that bind to antigens produced by foreign invaders.
Responsible for antibody production, b-lymphocytes, with the assistance of helper t-cells, become activated after they recognize a specific antigen and bind to the receptors on its surface. They then divide into identical b-cell clones. Each cloned b-cell produces antibodies specifically for the particular antigen responsible for activation of the b-cell of origin. From this point, b-lymphocytes then differentiate either as plasma cells or will become memory cells.
Stationed permanently in the lymph nodes until cell death occurs, the job of a plasma cell is the secretion of antibodies, which move into the blood and lymph nodes, destined for the site of infection. Providing continued immunity long after the infection is gone, memory cells do not succumb to apoptosis, or programmed cell death, as plasma cells do. B memory cells have a gene activated within them, allowing them to live longer, so that if the particular microbe attempts to attack again later, the response will be faster.
Immunization provides an artificial means to develop continued active immunity, occurring as result of antigen exposure through the administration of a vaccine. Once a vaccine is given, adaptive immune responses are activated, producing b-cell clones, antibodies, plasma cells, and memory cells. Developed to cause immunity while not resulting in actual illness, vaccines are produced from pathogens that have been altered in some way, or killed. Proteins from pathogens are also used in the formulation of vaccines.