adaptive immune response

Definition

Target type: biologicalprocess

An immune response mediated by cells expressing specific receptors for antigens produced through a somatic diversification process, and allowing for an enhanced secondary response to subsequent exposures to the same antigen (immunological memory). [GO_REF:0000022, GOC:add, ISBN:0781735149]

Adaptive immune response is a highly specific and complex defense mechanism that allows the immune system to recognize and eliminate pathogens, such as bacteria, viruses, and parasites, as well as abnormal cells, like cancer cells. Unlike the innate immune response, which is non-specific and immediate, the adaptive immune response is acquired over time and provides long-lasting protection against specific threats.

The key features of the adaptive immune response are:

1. Specificity: Adaptive immune cells recognize and target specific antigens, which are unique molecules found on pathogens or abnormal cells. This specificity is achieved through the expression of diverse antigen receptors, such as antibodies and T cell receptors.
2. Memory: After an initial encounter with a pathogen, the adaptive immune system remembers the specific antigen and mounts a faster and more effective response upon subsequent exposures. This is due to the formation of memory cells, which persist for long periods and can rapidly proliferate and differentiate into effector cells upon re-exposure to the same antigen.
3. Tolerance: The adaptive immune system is able to distinguish between self and non-self antigens, preventing the destruction of healthy tissues. This self-tolerance is established during immune development and is maintained through various mechanisms, such as deletion of self-reactive lymphocytes and regulatory T cell suppression.

The adaptive immune response is mediated by two main types of lymphocytes: B cells and T cells.

B cells are responsible for humoral immunity, which involves the production of antibodies. Antibodies are proteins that circulate in the blood and lymph and bind specifically to antigens, neutralizing them or marking them for destruction by other immune cells. The process of antibody production is called humoral immunity.

T cells are responsible for cell-mediated immunity, which involves the direct killing of infected or abnormal cells. T cells express T cell receptors (TCRs) that recognize specific antigens presented on the surface of antigen-presenting cells (APCs). APCs, such as macrophages and dendritic cells, engulf pathogens and break them down into smaller peptide fragments, which are then displayed on MHC molecules. The TCR on T cells can bind to these MHC-peptide complexes and activate the T cells, leading to the destruction of infected or abnormal cells.

The adaptive immune response is a tightly regulated process that involves a complex interplay of different cell types and signaling molecules. Dysregulation of the adaptive immune response can lead to autoimmune diseases, allergies, and immunodeficiency disorders.

Here is a more detailed description of the steps involved in the adaptive immune response:

1. Antigen recognition: B cells and T cells express unique antigen receptors that allow them to recognize and bind to specific antigens.
2. Antigen presentation: APCs capture and process antigens and present them on their surface in conjunction with MHC molecules.
3. T cell activation: T cells recognize and bind to antigen-MHC complexes presented by APCs, leading to T cell activation and differentiation.
4. B cell activation: B cells recognize and bind to antigens, leading to B cell activation and differentiation into plasma cells, which secrete antibodies.
5. Antibody production: Plasma cells produce and secrete antibodies that specifically bind to the antigen.
6. Effector functions: Antibodies neutralize pathogens or mark them for destruction by other immune cells, while cytotoxic T cells directly kill infected or abnormal cells.
7. Memory cell formation: Some activated B cells and T cells differentiate into memory cells, which provide long-lasting protection against future infections.

This intricate process ensures that the immune system can effectively eliminate pathogens and maintain immune homeostasis.'
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Compounds (3,421)