5. Adaptive Immunity

What are the three main characteristics of adaptive immunity

Specificity, adaptation, and memory

What does specificity in adaptive immunity refer to

The immune response is specific for individual antigens

How does adaptation occur in adaptive immunity

The immune system modifies its response upon contact with an antigen

What is immunological memory

Previous contact with an antigen changes the subsequent response both qualitatively and quantitatively

What are the two types of lymphoid organs

Primary and secondary lymphoid organs

What are two primary lymphoid organs

Bone marrow and thymus

List three secondary lymphoid organs

Lymph nodes, spleen, and Peyer's patches

What is MALT

Mucosa-Associated Lymphoid Tissues

What does APC stand for

Antigen Presenting Cell

What is the main function of MHC molecules

To bind and present antigens to T cells

What are the two main classes of MHC molecules

MHC class I and MHC class II

Which cells express MHC class II molecules

Macrophages, dendritic cells, and B cells

What do B cells produce

Antibodies

What are the two main types of T cells

CD4+ T cells and CD8+ T cells

What do T cells recognize

Antigen bound to MHC molecules

What do B cells recognize

Free, linear, and 3D antigen structures

What is clonal selection

The process of activating specific lymphocytes that recognize a particular antigen

What is affinity maturation

The process of increasing antibody affinity for antigens over time

What is isotype switching

Changing the antibody class without altering antigen specificity

What are the main components of an antibody

Two heavy chains and two light chains

What are the five main antibody isotypes

IgA, IgG, IgM, IgD, and IgE

What is the function of the variable region in antibodies

To bind specific antigens

What is the function of the constant region (Fc) in antibodies

To interact with immune cells and activate complement

What do CD4+ T cells primarily do

Regulate adaptive immunity and produce cytokines

What is the main function of CD8+ T cells

Cytotoxic cell killing

Which MHC class do CD4+ T cells recognize

MHC class II

Which MHC class do CD8+ T cells recognize

MHC class I

What is an antigen

A piece of pathogen or molecule that binds to antibodies or TCRs.

What is an APC's role in immunity

To process and present antigens to T cells.

What does MHC stand for

Major Histocompatibility Complex.

What is isotype switching in antibodies

The alteration of an antibody's constant region without changing its specificity.

What does clonal selection refer to in immunology

The activation of specific lymphocytes that recognize a particular antigen.

What occurs in the primary lymphoid organs

Development and maturation of lymphocytes

What occurs in the secondary lymphoid organs

Mature lymphocytes encounter antigens and initiate immune responses

What are encapsulated tissues

Lymph nodes and spleen

What are unencapsulated tissues

Mucosa-Associated Lymphoid Tissues (MALT) and cutaneous surfaces

What do B lymphocytes do in primary lymphoid organs

Undergo development in the bone marrow

What happens to immature T cells in primary lymphoid organs

They are exported to the thymus for final maturation

What happens in the lymph nodes

Immune responses to tissue pathogens and most vaccines are induced

What happens in the spleen

It filters the blood and is a major site for detecting and responding to blood-borne pathogens

What happens in the MALT

It combats infections that enter the body via mucosal surfaces

What is an antigen

Any molecule recognized by specific receptors of the adaptive immune system on T cells and B cells

What is an immunogen

A molecule capable of eliciting an immune response

What is an epitope

The portion of an antigen that makes contact with a particular antibody or T cell receptor

What is a hapten

A low molecular weight compound that is not immunogenic by itself but can elicit immune responses when coupled to a carrier

What is the Major Histocompatibility Complex (MHC)

Cell surface molecules that present antigens to T cells and induce adaptive immune responses

What are lymphatic organs

Tissues where leukocytes mature, differentiate, and proliferate

What are primary lymphoid organs

Major sites of lymphopoiesis where B and T lymphocytes differentiate from stem cells

What are secondary lymphoid organs

Where mature lymphocytes fight off germs and foreign substances

What is somatic recombination

Gene rearrangement in the variable region of antigen receptors during early B and T cell development

What is clonal selection

The process of activating specific lymphocytes with receptors recognizing a particular antigen

What is clonal expansion

Rapid division of selected lymphocytes to produce a large number of identical cells

What are lymphocyte clones

Groups of identical lymphocytes derived from a single parent cell with the same antigen receptor

What are monoclonal antibodies

Identical antibodies produced by a single clone of B cells, targeting the same specific epitope

What are polyclonal antibodies

A mixture of antibodies produced by different B cell clones, recognizing multiple epitopes on the same antigen

What is antibody affinity

The binding strength between an antibody and its specific antigen

What is somatic hypermutation

A process of high-rate point mutations in antibody gene variable regions to generate higher-affinity antibodies

What is affinity maturation

The process of selecting and proliferating B cells with higher-affinity antibodies over time

What is class switching

A process allowing mature B cells to change antibody class without altering antigen specificity

What is the Fab region of an antibody

The arm region that binds to the antigen, consisting of one light chain and part of one heavy chain

What is the Fc region of an antibody

The tail region that interacts with cell surface receptors and complement proteins

What is agglutination

The clumping of particles due to cross-linking action of antibodies binding to multiple particles

What is precipitation in immunology

The aggregation of soluble antigens and antibodies, forming immune complexes that settle out of solution

What is neutralization in immunology

The process of antibodies binding to pathogens or toxins, blocking their ability to infect cells or exert harmful effects

IgG

Highest conc in blood, escape blood vessels easily, activate classical complement pathway, causes agglutination and opsonization

IgM

Produced during primary immune response, secreted as pentamer, do not enter tissue fluids, activate classical complement pathway

Is IgG or IgM more efficient at complementing activation?

IgM

IgA

Produced by plasma cells, go into intestine, bronchi or milk, major immunoglobulin in external secretions of nonruminants, agglutinate particulate antigens and neutralize viruses

IgE

Mostly bound to tissue mast cells, eliminate parasitic worms, does not act like other immunoglobulins do