An antigen is defined as any substance capable of eliciting an immune response. Infectious organisms such as bacteria, foreign matter, and even tumor cells have antigens within their makeup and lining their outer surfaces. Since the body does not recognize such an antigen as one of its own, it mounts an immune response against it to try to eliminate it.
On initial exposure to an antigen, B lymphocytes start to divide and differentiate into their antibody-producing form. It might take up to 7 days before antibody production can be achieved. Even then, production is only moderate, and adequate levels generally last only about 3 weeks. In the meantime, however, other immune components, such as neutrophils, macrophages, and killer cells, are called in to fight off the invader.
If the invader is a tumor cell, foreign body, or an organism that lives and multiplies within body cells (such as viruses do), then the T lymphocytes start to multiply and prepare themselves for battle as well. As with the B lymphocytes, they are specific for each antigen; that is, a lymphocyte that responds to one type of antigen will not respond to any others. As a result, each different antigen that enters the body will stimulate its own group of antagonistic B and T lymphocytes.
Following this initial exposure, the lymphocytes that have been primed to the antigen retain “memory” of the experience. Sent to the front-line defenses, they simply wait for the antigen to show up again. If it ever does, the lymphocytes are ready for it, without the 7day lag time. Antibodies are produced in high levels almost immediately, and the T cells are primed and sent into action with minimal delay.
On initial exposure to an antigen, B lymphocytes start to divide and differentiate into their antibody-producing form. It might take up to 7 days before antibody production can be achieved. Even then, production is only moderate, and adequate levels generally last only about 3 weeks. In the meantime, however, other immune components, such as neutrophils, macrophages, and killer cells, are called in to fight off the invader.
If the invader is a tumor cell, foreign body, or an organism that lives and multiplies within body cells (such as viruses do), then the T lymphocytes start to multiply and prepare themselves for battle as well. As with the B lymphocytes, they are specific for each antigen; that is, a lymphocyte that responds to one type of antigen will not respond to any others. As a result, each different antigen that enters the body will stimulate its own group of antagonistic B and T lymphocytes.
Following this initial exposure, the lymphocytes that have been primed to the antigen retain “memory” of the experience. Sent to the front-line defenses, they simply wait for the antigen to show up again. If it ever does, the lymphocytes are ready for it, without the 7day lag time. Antibodies are produced in high levels almost immediately, and the T cells are primed and sent into action with minimal delay.
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