What is the primary function of the thymus in T-cell development?

The thymus is the site where progenitor T-cells migrate for maturation, involving positive and negative selection.

Which of the following is a primary lymphoid organ? A) Lymph node B) Spleen C) Thymus D) MALT

C) Thymus

What percentage of double positive T-cells undergo positive selection in the thymus?

Approximately 5% of double positive T-cells undergo positive selection.

Define the role of Hassall's corpuscles in the thymus.

Hassall's corpuscles are layers of degenerating epithelial cells found in the medulla of the thymus.

Which cytokine is primarily responsible for influencing TH cell responses?

Interleukin-1 (IL-1) is primarily responsible for influencing TH cell responses.

What are the two main types of effector T-cells?

The two main types of effector T-cells are CD4+ helper T-cells and CD8+ cytotoxic T-cells.

Which type of immune cell is primarily responsible for the destruction of infected cells?

CD8+ cytotoxic T-cells are primarily responsible for the destruction of infected cells.

What are the components of the white pulp in the spleen?

The white pulp of the spleen consists of the periarteriolar lymphoid sheath (T-cell area) and the marginal zone (B-cell area).

Which of the following is NOT a characteristic of Natural Killer (NK) cells? A) Antigen specificity B) Cytotoxic activity C) Part of innate immunity D) No prior antigen exposure required

A) Antigen specificity

What is the primary role of antibody-dependent cellular cytotoxicity (ADCC)?

ADCC facilitates the destruction of target cells marked by antibodies by various immune cells.

What distinguishes primary lymphoid follicles from secondary lymphoid follicles in lymph nodes?

Primary lymphoid follicles contain resting B-cells, while secondary lymphoid follicles contain activated B-cells after antigen exposure.

Which cells are primarily involved in the humoral immune response?

B-cells are primarily involved in the humoral immune response.

What is the function of M cells in mucosa-associated lymphoid tissue (MALT)?

M cells serve as entry points for microbes and are involved in the transport of antigens across the epithelial barrier.

Which cytokines do TH1 cells primarily release to promote cell-mediated immunity?

TH1 cells primarily release cytokines such as IL-2 and interferon-gamma (IFN-γ) to promote cell-mediated immunity.

Which type of antigen-presenting cells are highly efficient in presenting antigens to T-helper cells?

Professional antigen-presenting cells, including macrophages, dendritic cells, and B-cells, are highly efficient in antigen presentation.

What unique receptor do γδ T-cells express instead of the more common α/β chains?

Γδ T-cells express γ/δ T-cell receptor chains instead of α/β chains.

What is the role of cytokines in the activation of B-cells during the humoral immune response?

Cytokines produced by activated TH cells provide necessary signals for the activation and differentiation of B-cells.

Which type of B-cell primarily produces antibodies during the immune response?

Plasma cells, differentiated from activated B-cells, primarily produce antibodies.

What happens to T-cells that fail to recognize self-MHC molecules during maturation?

T-cells that fail to recognize self-MHC molecules undergo apoptosis, a process known as death by neglect.

Which immune response is primarily responsible for protecting against intracellular pathogens?

Cell-mediated immunity (CMI) is primarily responsible for protecting against intracellular pathogens.

What is the significance of the germinal center in secondary lymphoid follicles?

The germinal center is where B-cells undergo activation, proliferation, and differentiation into plasma and memory cells.

Which molecules are involved in the costimulatory signal during TH cell activation?

CD28 on TH cells interacts with B7 molecules on antigen-presenting cells to provide the costimulatory signal.

What type of hypersensitivity reaction is delayed by cell-mediated immunity?

Type IV hypersensitivity reactions are delayed by cell-mediated immunity.

What is the primary function of complement factors coded by MHC region III?

Complement factors coded by MHC region III are involved in enhancing the immune response and promoting pathogen destruction.

Which cytokine is critical for the proliferation and activation of cytotoxic T-cells?

Interleukin-2 (IL-2) is critical for the proliferation and activation of cytotoxic T-cells.

Which immune cells are involved in antibody-dependent cell-mediated cytotoxicity (ADCC)?

NK cells, neutrophils, eosinophils, and macrophages are involved in ADCC.

What is the primary source of macrophages in the immune system?

Macrophages originate from monocytes, which are derived from granulocyte-monocyte progenitor cells in the bone marrow.

Which lymphocytes are identified by the surface markers CD4, CD25, and Foxp3?

Regulatory T-cells (TREG) are identified by the surface markers CD4, CD25, and Foxp3.

Which layer of the thymus contains densely packed thymocytes?

The cortex of the thymus contains densely packed thymocytes.

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

Dendritic cells serve as antigen-presenting cells that capture and present antigens to T-cells.