Cell Mediated Immunity and Hypersensitivity

A collection of flashcards designed to help review key concepts in Cell Mediated Immunity and Hypersensitivity.

What is the definition of hypersensitivity in immunology?

An exaggerated or inappropriate immune response causing tissue damage.

What are the four classic types of hypersensitivity?

Type 1 = allergic, Type 2 = mediated by antibodies, Type 3 = mediated by antigen-antibody complexes, Type 4 = cell mediated.

What cell type is primarily involved in the coordination of immune responses?

CD4+ T cells.

What function do cytokines perform?

They act as secreted glycoproteins with local actions, modulating various immune responses.

What is the primary role of CD4+ T cells?

To help B cells produce antibodies and to activate macrophages and cytotoxic T cells.

What condition is caused by maternal anti-RhD antibodies during pregnancy?

Haemolytic disease of the newborn.

What are the three main types of cells that CD4+ T cells can help activate?

B cells, macrophages, and CD8+ cytotoxic T cells.

What is the Mantoux test used for?

To assess whether antigen-specific Th1 cells are present, indicating latent TB infection.

What is the result of neutralization by antibodies?

Antibodies prevent pathogens from binding to cell surfaces.

What type of hypersensitivity involves IgE antibodies?

Type I hypersensitivity.

Which subtype of T helper cells promotes antibody formation?

T follicular helper (TFH) cells.

What role do macrophages play in the immune response?

They phagocytize pathogens and present antigens to T cells.

How do neutralizing antibodies function against toxins?

They prevent toxins from binding to cell surface receptors.

What is the relationship between B cells and T follicular helper cells?

TFH cells help B cells produce optimal types and quantities of antibodies.

What mediates Type II hypersensitivity?

Antibodies (IgG, IgM) against antigens on the surface of affected cells.

What is the result of excessive CD4+ T cell function?

Autoimmune diseases and allergic reactions.

What type of hypersensitivity involves antigen-antibody complexes?

Type III hypersensitivity.

Examples of conditions related to Type IV hypersensitivity include:

Insulin-dependent diabetes mellitus, multiple sclerosis, and Hashimoto’s thyroiditis.

What is the primary mediator in cell-mediated hypersensitivity?

Th1 cells.

What is the significance of the term 'pro-inflammatory cytokines'?

They can be blocked in inflammatory disorders.

What is one characteristic of helper T cells (CD4+ T cells)?

They do not directly attack pathogens but help other cells in the immune response.

What is an antigen presenting cell (APC)?

A cell that presents antigens to T cells, crucial for immune activation.

What do cytotoxic T cells primarily target?

Infected or cancerous cells.

Which cytokine is crucial for activating macrophages?

Interferon-gamma (IFN-γ).

In which circumstance are immunological memory responses not typically induced?

When a tetanus booster is given to someone without sufficient neutralizing antibodies.

What are the potential consequences of allergic reactions?

Tissue damage and inflammatory responses.

What characterizes a Type I hypersensitivity response?

IgE-mediated release of histamines from mast cells.

Which immune cells are responsible for producing antibodies?

B cells.

What is the role of CD8+ T cells in the immune system?

To kill infected or tumorous cells.

What is one effect of the complement system in phagocytosis?

It enhances the ingestion of antigen-antibody complexes by phagocytes.

What defines Type III hypersensitivity reactions?

The deposition of antigen-antibody complexes in tissues.

What type of immune response occurs in infections like tuberculosis?

Delayed-type cell-mediated hypersensitivity.

What type of antibodies are effective in mucosal immunity?

Secreted IgA.

What is a common clinical test for tuberculosis exposure?

The Mantoux test.

What triggers the release of INF-γ in the immune response?

Activation of Th1 cells by antigen presentation.

What is the function of regulatory T (Treg) cells?

To limit immune responses and prevent autoimmunity.

What type of transplants may be affected by Type II hypersensitivity?

Mismatched blood transfusions.

How do vaccines utilize the immune response?

By stimulating the production of memory B and T cells.

What is tissue damage due to autoantibodies classified as?

Type II hypersensitivity.

What immune component is often involved in allergic responses?

IgE antibodies.

What is the role of Th2 cells in the immune system?

They stimulate responses against extracellular parasites and promote allergic reactions.

What kind of immune response is characterized by a peak 24-48 hours after exposure?

Type IV or delayed-type hypersensitivity.

What is the main target of vaccines in the immune system?

To produce long-lasting immunity through memory cells.

How is tissue inflammation mediated in Type III hypersensitivity?

By Fc receptor activation and complement pathways.

What are the potential risks of a mismatched blood transfusion?

Type II hypersensitivity reaction leading to hemolysis.

What do autoreactive T and B cells contribute to?

The development of autoimmune diseases.

How can excessive inflammation in the body be managed?

By targeting and blocking pro-inflammatory cytokines.

What do cytokines such as interleukins primarily act on?

Leukocytes to modulate immune responses.

How does the immune system protect against viral infections?

By neutralizing antibodies and T cell responses.