immune response

Definition

Target type: biologicalprocess

Any immune system process that functions in the calibrated response of an organism to a potential internal or invasive threat. [GO_REF:0000022, GOC:add]

The immune response is a complex biological process that involves the coordinated action of various cells and molecules to defend the body against pathogens and other foreign invaders. This intricate defense mechanism encompasses several steps, including:

1. **Recognition of pathogens:** The immune system distinguishes self from non-self through specialized immune cells called antigen-presenting cells (APCs), such as macrophages and dendritic cells. These cells engulf pathogens and break them down into smaller fragments, called antigens, which are displayed on the surface of the APC.
2. **Activation of immune cells:** When an antigen is presented, it triggers the activation of specific immune cells, namely T lymphocytes (T cells) and B lymphocytes (B cells). T cells are responsible for cell-mediated immunity, while B cells are responsible for antibody-mediated immunity.
3. **T cell activation and differentiation:** Helper T cells (TH cells) are activated upon recognizing the antigen presented by APCs. These activated TH cells release cytokines, which are signaling molecules that stimulate the proliferation and differentiation of other immune cells, including cytotoxic T cells (TC cells) and B cells.
4. **B cell activation and antibody production:** B cells are activated by the interaction with antigens and with help from TH cells. Activated B cells differentiate into plasma cells, which produce and secrete antibodies specific to the antigen.
5. **Elimination of pathogens:** Antibodies produced by B cells bind to pathogens, neutralizing their infectivity, marking them for destruction by other immune cells, or activating the complement system, which leads to lysis of the pathogen. TC cells directly kill infected cells or cancerous cells by releasing cytotoxic molecules.
6. **Memory response:** Following an initial encounter with a pathogen, the immune system develops memory cells, which are long-lived T and B cells specific to the pathogen. This allows for a faster and more efficient response upon subsequent exposures to the same pathogen.

This highly coordinated response ensures effective elimination of pathogens and protection from future infections. The immune response is a dynamic and adaptive process, constantly evolving and improving its ability to protect the body from a wide range of threats.'
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Proteins (76)

Compounds (2,623)