T-helper 1 type immune response

Definition

Target type: biologicalprocess

An immune response which is associated with resistance to intracellular bacteria, fungi, and protozoa, and pathological conditions such as arthritis, and which is typically orchestrated by the production of particular cytokines by T-helper 1 cells, most notably interferon-gamma, IL-2, and lymphotoxin. [GOC:add, ISBN:0781735149]

T-helper 1 (Th1) type immune response is a critical arm of the adaptive immune system, primarily targeting intracellular pathogens like viruses, bacteria, and parasites. It is characterized by the production of a distinct set of cytokines, primarily interferon-gamma (IFN-γ), which orchestrate the elimination of these invaders.

The initiation of a Th1 response begins with the encounter of antigen-presenting cells (APCs), such as macrophages and dendritic cells, with the pathogen. These APCs engulf and process the pathogen, displaying its antigens on their surface via major histocompatibility complex (MHC) class II molecules. This antigen presentation triggers the activation of naïve CD4+ T cells, which are the precursors to Th1 cells.

Upon activation, naïve CD4+ T cells differentiate into Th1 cells under the influence of specific cytokines. Interleukin-12 (IL-12) produced by APCs plays a crucial role in this differentiation process. IL-12, together with other signals, stimulates the transcription factor T-bet, a master regulator of Th1 differentiation.

Once differentiated, Th1 cells become potent effectors of the immune response. They secrete IFN-γ, which acts on a variety of target cells to eliminate the pathogen. IFN-γ enhances the microbicidal activity of macrophages, promoting their ability to engulf and destroy intracellular pathogens. It also activates natural killer (NK) cells, which are cytotoxic lymphocytes that directly kill infected cells.

Th1 cells also produce tumor necrosis factor-alpha (TNF-α), which contributes to inflammation and tissue damage. However, TNF-α also plays a role in activating macrophages and neutrophils, further contributing to the clearance of pathogens.

In addition to these direct effects, Th1 cells contribute to the development of long-lasting immunity. They help generate memory T cells, which are specialized cells that remember the specific pathogen and can rapidly mount a response upon re-exposure. This immune memory is essential for preventing reinfection and disease.

In summary, the Th1 type immune response is a highly effective defense mechanism against intracellular pathogens. It involves the differentiation of naïve CD4+ T cells into Th1 cells, the production of key cytokines like IFN-γ, and the activation of effector cells such as macrophages, NK cells, and neutrophils. This coordinated response effectively eliminates the pathogen while also generating long-lasting immune memory.'
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Proteins (2)

Compounds (9)