Physiology, Active Immunity

Excerpt

The body’s immune system is crucial in preventing invasion and harm from a variety of microbiological organisms such as bacteria, viruses, fungi, and parasites. Many levels of protection are involved in this process. Physical barriers such as skin, mucous membranes, and the acidic environment of the gastrointestinal (GI) tract provide the initial defense. If these fail, the innate or non-specific immune system is next to respond.

Innate immunity involves the release of cytokines, complement, and chemokines, as well as neutrophils and macrophages to destroy the invading pathogens. When this is not enough, an antigen-specific or adaptive immune response becomes initiated, and antibodies, B cells, and T cells enter the battle. The generation of a specific response to an antigen is referred to as active immunity. Active immunity plays a vital role in immune responses in the event of re-exposure and our utilization of vaccines.