Lymphoid

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Questions and Answers

Which enzyme hydrolyzes bacterial cell wall components, killing those cells?

Cytokines

Defensins

Lysozyme (correct)

Interferons

What is the main function of complement in innate immunity?

Aiding removal of bacteria by reacting with bacterial surface components (correct)

Signaling NK cells to kill virus-infected cells

Stimulating phagocytosis

Killing bacteria by disrupting the cell walls

What is the characteristic of adaptive immune responses that sets them apart from innate immunity?

Nonspecific response

Rapid memory lymphocyte production

Fast response time

Specific microbial invaders (correct)

What is the primary function of natural killer cells in innate immunity?

Killing virus-infected cells Signup and view all the answers

What is the role of antibodies in the immune response to antigens?

Interacting specifically with antigenic determinants Signup and view all the answers

In what way do adaptive immune responses differ from innate immunity?

Involvement of B and T lymphocytes Signup and view all the answers

What is the main function of the immune system?

To protect the organism from the effects of all nonself substances Signup and view all the answers

Which type of immunity involves immediate, nonspecific actions?

Innate immunity Signup and view all the answers

Which cells destroy various unhealthy host cells?

Natural killer cells Signup and view all the answers

What do Toll-like receptors (TLRs) on leukocytes allow?

Recognition and binding of surface components of invaders Signup and view all the answers

Which leukocytes remove invaders that manage to penetrate physical barriers?

Neutrophils Signup and view all the answers

What is the term for the immune response that is adaptive and acquired?

(Acquired) Adaptive immunity Signup and view all the answers

What is the function of Helper T cells?

Producing cytokines that promote differentiation of B cells into plasma cells Signup and view all the answers

Which molecule do Helper T cells bind to with their TCR for promoting immune responses?

MHC class II molecules Signup and view all the answers

What is the specific function of CTLs?

Killing infected or abnormal cells Signup and view all the answers

Which coreceptor is involved in the binding of CTLs to specific antigens?

CD8 Signup and view all the answers

Why are T lymphocytes said to be MHC restricted?

Because they recognize antigenic peptides only when presented as part of MHC molecules Signup and view all the answers

What is a characteristic feature of memory helper T cells?

They allow a more rapid response if the antigen appears again later Signup and view all the answers

Where are MHC class II proteins synthesized and transported to the cell surface?

In cells of the mononuclear phagocyte system and certain other cells under some conditions Signup and view all the answers

What is the function of MHC class I molecules presenting 'self-antigens' on the surfaces of cells?

To ignore those cells by T cells Signup and view all the answers

Which cells are responsible for antigen presentation to lymphocytes?

Dendritic cells and lymphocytes Signup and view all the answers

What is the role of interferon-γ in certain local cells during inflammation?

Inducing the expression of MHC class II molecules Signup and view all the answers

What is the primary function of T-cell receptors (TCRs)?

Binding antigens directly Signup and view all the answers

Where do B lymphocytes mature and differentiate further?

In the bone marrow Signup and view all the answers

Which part of the antibody molecule is recognized by cell surface receptors on basophils and mast cells?

Constant Fc region Signup and view all the answers

Which class of antibody is highly soluble, stable, and able to cross the placental barrier into the fetal circulation?

IgG Signup and view all the answers

Which antibody class is mainly produced in an initial response to an antigen and is the most effective in activating the complement system?

IgM Signup and view all the answers

Which immunoglobulin is much less abundant in the circulation and exists bound at its Fc region to receptors on the surface of mast cells and basophils, triggering allergic reactions?

IgE Signup and view all the answers

What is the least abundant immunoglobulin in plasma and acts as an antigen receptor in triggering B-cell activation?

IgD Signup and view all the answers

Which action of antibodies refers to the ability to bind specifically and neutralize certain viral particles and bacterial toxins, agglutinate many bacterial cells, and precipitate most soluble antigens?

Opsonization Signup and view all the answers

Study Notes

Enzymatic Action and Immune Responses

Lysozyme hydrolyzes bacterial cell wall components, leading to cell death.
Complement plays a crucial role in innate immunity by enhancing opsonization, promoting inflammation, and directly lysing pathogens.

Differences Between Immune Responses

Adaptive immune responses are characterized by specificity and memory, differentiating them from rapid and nonspecific innate immunity.
Immediate, nonspecific actions are associated with innate immunity.

Cellular Components and Functions

Natural killer cells destroy various unhealthy host cells, including tumor and virus-infected cells.
Toll-like receptors (TLRs) enable leukocytes to recognize pathogen-associated molecular patterns (PAMPs), activating immune responses.
Phagocytic leukocytes like macrophages and neutrophils remove invaders that breach physical barriers.

Adaptive Immunity Dynamics

The adaptive immune response is also known as acquired immunity, featuring specific responses to pathogens.
Helper T cells bind to MHC class II molecules on antigen-presenting cells (APCs) with their TCR, promoting immune responses.

T Cell Functions and Characteristics

Cytotoxic T lymphocytes (CTLs) specifically kill infected or abnormal cells.
CTLs utilize CD8 coreceptors to enhance binding to target antigens presented by MHC class I molecules.
T lymphocytes are MHC restricted, meaning they recognize antigens only if presented by MHC molecules.
Memory helper T cells persist long-term after an initial immune response, facilitating faster responses to future infections.

Antigen Presentation and Immune Mechanisms

MHC class II proteins are synthesized in the endoplasmic reticulum and transported to the cell surface for antigen presentation.
MHC class I molecules present 'self-antigens' to help the immune system differentiate between healthy and unhealthy cells.
Antigen-presenting cells such as dendritic cells, macrophages, and B cells present antigens to lymphocytes.

Cytokines and Their Roles

Interferon-γ modulates the activity of certain local cells during inflammation, enhancing immune responses.

B Cells and Antibody Functions

B lymphocytes mature in bone marrow and further differentiate to produce antibodies.
The Fc region of antibodies is recognized by cell surface receptors on basophils and mast cells, triggering allergic reactions.
IgG is a stable, highly soluble antibody capable of crossing the placental barrier, providing fetal immunity.
IgM is produced primarily during the initial immune response and is effective in activating the complement system.
IgE, though less abundant, binds to mast cells and basophils, playing a key role in allergic reactions.
IgD, the least abundant immunoglobulin, serves as an antigen receptor that triggers B-cell activation.

Functions of Antibodies

Antibodies can specifically bind to and neutralize viruses and toxins, agglutinate bacterial cells, and precipitate soluble antigens, demonstrating diverse protective roles in the immune response.

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Description

Test your knowledge about the structure and functions of immunoglobulins, including the design of antibody molecules, the Fc region, and their recognition by cell surface receptors. This quiz covers essential concepts related to immunoglobulins.