Th2 cells

Definition

Th2 cells, or T helper 2 cells, are a subset of CD4+ T cells that play a vital role in the immune system by promoting antibody production and orchestrating the response to allergens and parasitic infections. These cells are crucial for activating B cells to produce immunoglobulins, particularly IgE, which is important in defending against parasites and mediating allergic responses. The activation of Th2 cells typically occurs through antigen presentation by dendritic cells and subsequent signaling from cytokines.

5 Must Know Facts For Your Next Test

1. Th2 cells secrete specific cytokines such as IL-4, IL-5, and IL-13, which help activate B cells and promote the production of IgE antibodies.
2. These cells are particularly important in the defense against helminth infections, as they help coordinate a strong immune response against parasitic worms.
3. The activation of Th2 cells can lead to allergic reactions when they respond to harmless environmental substances, resulting in conditions like asthma and hay fever.
4. In addition to promoting B cell differentiation, Th2 cytokines also recruit eosinophils and mast cells to sites of infection or inflammation.
5. An imbalance in Th1 and Th2 cell responses can contribute to various immune disorders, highlighting the importance of Th2 cells in maintaining immune homeostasis.

Review Questions

• How do Th2 cells contribute to the differentiation and activation of B cells in an immune response?
  • Th2 cells contribute to B cell differentiation by secreting cytokines such as IL-4 and IL-13, which are essential for stimulating B cells to produce antibodies. This process enhances the humoral immune response, particularly through the production of IgE antibodies that play a critical role in combating parasitic infections and mediating allergic responses. The interaction between Th2 cells and B cells is crucial for effective immunity against specific pathogens.
• Discuss the role of Th2 cells in allergic reactions and how they mediate these responses through cytokine release.
  • Th2 cells play a central role in allergic reactions by releasing cytokines such as IL-4 and IL-5, which promote IgE production and attract eosinophils. When an allergen is encountered, Th2 cells become activated and initiate a cascade of immune responses that lead to hypersensitivity. This process results in symptoms such as inflammation, mucus production, and tissue damage, illustrating the link between Th2 cell activation and allergic diseases.
• Evaluate the implications of Th2 cell imbalances in the context of immune system disorders and their potential treatments.
  • Imbalances between Th1 and Th2 cell responses can lead to various immune disorders. For instance, an overactive Th2 response can contribute to allergic diseases like asthma, while a weakened response may impair the body’s ability to fight off parasitic infections. Understanding these dynamics allows for targeted therapies that can modulate Th2 activity, offering potential treatments for allergies and related conditions by restoring balance in the immune system.

Related terms

Cytokines: Signaling proteins that are secreted by immune cells to communicate and regulate immune responses, influencing the activity of other immune cells.

B cells: A type of white blood cell that is responsible for producing antibodies in response to antigens, playing a key role in the adaptive immune response.

Allergy: An abnormal immune response to a normally harmless substance, often mediated by IgE antibodies produced in response to allergens due to Th2 cell activation.