nr222 adaptive immune function (2/2)

Comprehensive practice flashcards covering adaptive immune response characteristics, B and T cell maturation, antigen types, leukocyte activation, antibody classes, and HIV/AIDS pathophysiology.

What are the two different branches of the adaptive immune response?

Antibody-mediated (humoral) immunity and cell-mediated immunity.

Which types of lymphocytes are involved in antibody-mediated immunity?

B-cell lymphocytes.

Which types of lymphocytes are involved in cell-mediated immunity?

T-cell lymphocytes.

How is 'specificity' defined in the context of adaptive immune response characteristics?

The response can be focused on a single antigen.

What does the characteristic of 'diversity' mean for the adaptive immune system?

There is always at least one cell that can react against any antigen.

What is the meaning of 'inducibility' in the adaptive immune response?

The response is only turned on when triggered by a specific pathogen.

Define 'clonality' as a characteristic of the adaptive immune response.

The generation of millions of cells with the same specificity once a response is triggered.

What is 'tolerance' in the adaptive immune system?

The ability to distinguish self cells from invading pathogens and not react with self antigens.

What is the function of 'memory' in the adaptive immune response?

The rapid mobilization of lymphocytes preprogrammed to recall their first engagement with an antigen, providing long-term immunity.

Where are both B-cells and T-cells initially produced?

In the red bone marrow.

Where do B-cells undergo maturation?

In the bone marrow.

Where do T-cells migrate to for maturation?

The thymus.

Where do B and T lymphocytes move to after maturation to become activated by foreign antigens?

Secondary lymphoid tissues such as lymph nodes.

Why do lymph nodes (swollen glands) enlarge during a respiratory infection?

Because lymphocytes are proliferating in them to fight the infection.

What are antigens?

Cells, chemicals, or particles that activate B-cells or T-cells and stimulate resistance to an infection.

What are examples of 'good' antigens that stimulate a strong immune response?

Large and complex molecules like proteins, lipoproteins, glycoproteins, nucleoproteins, and polysaccharides.

What are alloantigens?

Antigens that occur in some members of a species but not others, such as human blood types.

How are superantigens defined?

Antigens that activate an extremely strong response from T-cells.

What is an epitope?

The specific region on an antigen to which an antibody binds.

What is a hapten?

A small molecule (like a drug or metal) that cannot elicit an immune response alone but can when attached to a larger carrier protein.

Which cells serve as antigen-presenting cells (APCs)?

Macrophages, B-cells, and dendritic cells.

To which cell type do APCs present the MHC-II protein and antigen complex?

T helper ($CD4$) cells.

What chemicals do APCs secrete to stimulate $CD4$ cells to differentiate?

Cytokines.

To which cell type are antigens attached to MHC-I proteins presented?

Inactive $CD8$ cytotoxic T-cells.

Which interleukin is secreted by T helper cells to help activate $CD8$ cytotoxic T-cells?

$\text{Interleukin-2}$.

How do activated $CD8$ cytotoxic T-cells kill virally-infected cells?

By releasing the proteins perforin and granzyme.

Besides virally-infected cells, what other cells can cytotoxic T-cells attack?

Cancer cells and cells grafted from other humans or animals.

What is the result of cytotoxic T-cells attacking grafted tissue?

Graft versus host disease and tissue rejection.

What is T-independent activation of B-cells?

An interaction where the B-cell binds directly to a microbe antigen and is activated without T helper cell assistance.

What three types of advanced cells can an activated B-cell differentiate into?

Regulatory B-cells, memory B-cells, and plasma cells.

What is the function of plasma cells?

They act as antibody factories, secreting antibodies with the same specificity as the original B-cell.

What is the function of regulatory B-cells?

They proliferate and secrete $\text{IL-10}$ to regulate the T-cell response.

What is the structural composition of an antibody (immunoglobulin)?

A Y-shaped structure with four polypeptide chains (two heavy and two light) held together by disulfide bonds.

What are the Fab regions of an antibody?

Antigen-binding fragments located at the arms of the Y, composed of a heavy and light chain.

What is the Fc region of an antibody?

The crystallizable fragment or stem of the Y that attaches to immune system cells and molecules.

Which antibody isotype represents $80\%$ of all isotypes and can cross the placenta?

Immunoglobulin G ($IgG$).

Which antibody isotype is the first produced in an immune response and exists as a pentamer?

Immunoglobulin M ($IgM$).

Where is Immunoglobulin A ($IgA$) typically found?

In secretions (saliva, tears, mucus) as dimers or in breast milk and blood.

Which antibody isotype is associated with parasitic worm infections and allergic reactions?

Immunoglobulin E ($IgE$).

What is the characteristic role of Immunoglobulin D ($IgD$)?

It acts as a receptor on B-cells.

How long is the latent period between primary antigen exposure and the production of $IgM$ antibodies?

$7-10$ days.

What is the 'anamnestic response'?

A secondary immune response where memory cells are activated to almost immediately produce high levels of $IgG$.

When does natural active immunity occur?

In response to an infection, where the body creates its own antibodies and memory lymphocytes.

When does natural passive immunity occur?

Between mother and child pre-natally (placenta) and post-natally (breast milk).

What is artificial active immunity?

Immunity that occurs in response to vaccination with a pathogen antigen.

What is an example of artificial passive immunity?

The administration of antiserum (antibodies) to snake venom.

Which specific cells are infected by the human immunodeficiency virus (HIV)?

T helper ($CD4$) cells.

What happens to the HIV genome during its latent state in a T helper cell?

The viral genome is incorporated into the host's nuclear chromosome as a provirus.

Why does HIV lead to a wide range of infections in patients?

The loss of T helper cells inhibits both the antibody-mediated (B-cell) and cell-mediated (cytotoxic T-cell) branches of the adaptive immune response.

What does the acronym AIDS stand for?

Acquired immune deficiency syndrome.