Helper T Cells: TH1 cells, TH2 cells, TH17 cells, TFH cells and Treg cells (FL-Immuno/32)

Summary

This video explores the diverse roles of helper T cells in the immune response. It highlights five main subsets: Th1, Th2, Th17, regulatory T cells, and follicular helper T cells. Each subset plays a unique role in combating specific pathogens such as intracellular bacteria, parasites, fungi, and extracellular bacteria. Th1 cells help fight intracellular infections, Th2 cells target parasites, and Th17 cells deal with fungal and bacterial infections. Regulatory T cells suppress immune responses to prevent autoimmunity, while follicular helper T cells assist B cells in antibody production. Understanding these subsets is crucial for better immune system function and response.

Takeaways

• 😀 Helper T cells play a critical role in the immune system by aiding other immune cells to eliminate pathogens.
• 😀 Helper T cells are categorized into several subsets, each defined by the cytokines they produce, which influence their function.
• 😀 T helper type 1 cells help fight intracellular infections (like viruses and bacteria) by producing interferon gamma and interleukin 2.
• 😀 T helper type 2 cells are crucial for immune responses against parasites (like helminths) and stimulate eosinophils and mast cells.
• 😀 T helper type 2 cells release interleukin 4, 5, and 13 to promote immune defense, including antibody production and mucus secretion.
• 😀 T helper 17 cells are involved in combating fungal and extracellular bacterial infections, secreting interleukin 17 and 22.
• 😀 Interleukin 17 helps recruit neutrophils to the infection site and induces inflammation to combat infections.
• 😀 Regulatory T cells play a role in preventing autoimmunity by limiting excessive immune responses and tissue damage after an infection is cleared.
• 😀 Follicular helper T cells assist B cells in producing the correct antibodies to clear infections, primarily by secreting interleukin 21.
• 😀 The immune system needs diverse helper T cell subsets because different pathogens (viruses, bacteria, parasites) require specific immune responses.
• 😀 The cytokines produced by helper T cells not only regulate the differentiation of other T cells but also help activate other immune cells to eliminate pathogens effectively.

Q & A

What are Helper T cells, and why are they important for the immune system?

Helper T cells, specifically CD4 positive T cells, are crucial for coordinating the immune response. They help activate other immune cells to eliminate pathogens by secreting cytokines that communicate with and enhance the activity of various immune cells.

What is the role of the Master transcriptional regulator in Helper T cell differentiation?

The Master transcriptional regulator controls the expression of cytokines specific to each Helper T cell subset. This regulation ensures that each subset produces the appropriate cytokines necessary for defending against different types of pathogens.

Why are diverse types of Helper T cells necessary for our immune system?

Our body encounters various types of pathogens that differ in the sites they infect, the cells they target, and their ability to resist immune responses. Different Helper T cell subsets are needed to tailor immune responses to these varied pathogens.

How do Helper T cells contribute to fighting intracellular infections?

In response to intracellular infections like viruses or bacteria, Helper T cells, particularly TH1 cells, secrete interferon gamma, which activates macrophages to kill ingested pathogens. They also help produce antibodies that enhance phagocytosis through a process called opsonization.

What is the function of T helper type 2 cells in response to parasitic infections?

T helper type 2 cells are activated in response to parasitic infections, such as helminths. They secrete cytokines like IL-4, IL-5, and IL-13, which stimulate B cells to produce antibodies, activate eosinophils and mast cells, and help expel parasites from the body via mucus production.

What is the role of IL-17 in the immune response, particularly in the context of T helper 17 cells?

IL-17, produced by T helper 17 cells, plays a key role in defending against fungal and extracellular bacterial infections. It recruits neutrophils to the infection site, induces inflammation, and helps activate epithelial cells to produce antimicrobial peptides.

How do T helper 17 cells differ from other T helper subsets?

T helper 17 cells are distinguished by the cytokine IL-17, which they secrete. They are primarily involved in combating fungal and extracellular bacterial infections, whereas other T helper subsets focus on different types of infections like intracellular pathogens or parasites.

What are regulatory T cells, and how do they prevent autoimmunity?

Regulatory T cells help maintain immune balance by suppressing overactive immune responses. After an infection is cleared, they limit tissue damage by inhibiting excessive inflammation, preventing autoimmunity, and promoting immune system regulation.

What cytokines do regulatory T cells produce, and what is their function?

Regulatory T cells produce transforming growth factor beta (TGF-beta) and IL-10. These cytokines help suppress inflammation and immune responses, ensuring that the immune system does not overreact or attack the body's own cells.

How do follicular helper T cells assist B cells in clearing infections?

Follicular helper T cells secrete IL-21, which guides B cells to produce antibodies that are effective in eliminating infections. These cells play a key role in the humoral immune response by enhancing B cell activation and antibody production.