The Immune System

The Immune system is a set of mechanisms that help protect your body against certain types of germs, which can cause infection and disease. It is divided into an innate immune system and an adaptive immune system.

In the innate immune system, many cells, chemicals and proteins act together to detect pathogens. These mechanisms work within a few hours or days after an antigen appears in the body and prevent them from entering the bloodstream. They also remove and destroy any bacteria or viruses that are already in the body.

Individual lymphocytes, which are the most important part of the innate immune response, express a single type of receptor molecule on their surface that allows them to bind to a specific peptide (antigen) from a foreign substance or an abnormal cell. Each lymphocyte has enough copies of this receptor to recognize more than one billion different peptides.

Another component of the innate immune system is the phagocytic response, which involves special white blood cells that engulf and kill germs. These cells are called phagocytic lymphocytes and include neutrophils, monocytes and eosinophils.

These white blood cells are made in the bone marrow, where they originate and migrate to lymph nodes and other tissues throughout the body. They ingest antigens from the environment and then release cytokines that trigger other immune cells to react.

Besides these main types of white blood cells, there are several other cell types that are involved in the innate immune response as well. They include complement proteins, innate leukocytes and phagocytic cells.

In this response, the innate immune system is activated when an antigen-presenting cell (APC) recognizes a specific peptide from the pathogen and begins to present it to the lymphocytes. This enlists the help of the adaptive immune system by causing B and T cells to become activated, producing antibodies and cytotoxic T cells.

This antibody and cytotoxic cell response is also known as humoral immunity. The antigen-specific antibodies produced by B cells bind to the pathogen and neutralize it so that it cannot infect other cells. The cytotoxic T cells then seek out any infected body cells and destroy them.

The adaptive immune system is activated when the innate immune system fails to clear the pathogen from the body. It also works to develop an immunity for a new pathogen by recognizing it and generating immunologic memory. This enables it to quickly and effectively respond to future invaders by targeting them.

A key component of the adaptive immune system is the development of antigen-specific T and B cell receptors generated by gene rearrangements during development. These varying receptors produce an array of immune responses to pathogens and enhance the immune response to subsequent encounters with that pathogen through the formation of immunologic memory–i.e. “learning” from the initial encounter.

Adaptive immunity is important in combating disease because it uses the ability of immune cells to distinguish between the body’s own cells and unwanted invaders. It also helps prevent cancer by eliminating cells that become mutated and appear to be foreign. It is the immune cells’ capacity to identify cancerous cells that are a major reason why vaccinations provide lasting protection against disease.

KNOW MORE  : Labrada Mass Gainer