Unit 2 - AP2

Active Immunity

Immunity built up by the body's immune system in response to exposure to pathogens or vaccines, resulting in the production of memory cells and antibodies.

Acute Inflammation

The body’s rapid response to injury or infection, characterized by redness, heat, swelling, and pain. This process helps to eliminate pathogens and begin repair.

Adaptive Immune Response

A specific immune response where the body recognizes and targets specific pathogens through the activation of B-cells, T-cells, and antibodies. It results in the formation of memory cells, allowing for a quicker response to future infections.

Antibody

A protein released by mature B-cells, plasma cells, which binds to specific antigens. An immunoglobulin.

Afferent Lymphatic Vessels

Vessels that carry lymph fluid from peripheral tissues to lymph nodes, facilitating filtration and immune cell activation.

Antigen

A molecule or substance that is recognized by the immune system as foreign, triggering an immune response by activating B-cells and T-cells.

Antigen Processing

The intracellular breakdown of antigens into smaller peptide fragments that can bind to MHC molecules for presentation to T-cells, facilitating their activation.

Antigen Presentation

The display of processed antigen fragments on the surface of antigen-presenting cells (APCs) bound to MHC molecules, enabling T-cells to recognize and respond to the antigen.

Antigen Receptor

A specialized protein found on the surface of B and T-cells that recognizes and binds to specific antigens, initiating the immune response.

Antigenic Determinant (Epitope)

A specific region on an antigen that is recognized and bound by antigen receptors on B and T-cells, triggering an immune response.

B-Cells

Also called B-lymphocytes, oversee humoral immunity; their descendants differentiate into plasma cells and memory B-cells that produce antibodies.

Barrier Defenses

The body’s first line of defense against pathogens that prevent microorganisms from ‘entering the body and causing infection.

Bone Marrow

Tissue found inside bones that produces blood cells, including red blood cells, white blood cells, and platelets. The site of all blood cell differentiation and maturation of B lymphocytes.

Bronchus-Associated Lymphoid Tissue (BALT)

A collection of immune cells located in the lining of the bronchi that plays a crucial role in the immune response to inhaled pathogens.

Central Tolerance

The process by which developing B & T-cells are tested to ensure they do not react against the body's own tissues, preventing autoimmune responses.

Chemokine

A small signaling protein that attracts immune cells to sites of inflammation, injury, or infection.

Chronic Inflammation

A long term inflammatory response that lasts for months or years when the body is unable to eliminate the cause of injury, infection, or inflammation

Chyle

A milky, fat-rich substance formed in the small intestine during the digestion. It contains absorbed lipids and is transported through the lymphatic system to the bloodstream.

Cisterna Chyli

An enlarged sac at the base of the thoracic duct; the origin of the thoracic duct that collects chyle from the intestinal lymphatic vessels.

Class Switching

The process by which a B cell changes the class of antibody it produces, such as from IgM to IgG, without altering the specificity for the antigen.

Clonal Anergy

A state in which B or T cells become functionally inactive and unresponsive to their specific antigen, preventing autoimmunity.

Clonal Deletion

the process by which self-reactive B or T cells are eliminated through apoptosis during lymphocyte development to prevent autoimmunity.

Clonal Expansion

The rapid proliferation of activated B or T-cells into a large number of identical cells that respond to a specific antigen, enhancing the immune response.

Clonal Selection

The process by which specific B or T cells are activated and proliferate upon encountering their antigen, leading to an enhanced immune response.

Clone

Descendents of a single cell.

Complement

A group of proteins in the blood that assist in the destruction of pathogens by marking them for destruction or promoting inflammation.

Constant Region Domain

The part of an antibody whose amino acid sequence stays relatively the same among antibodies of the same class. Does not bind to antigens and is responsible for mediating effector functions.

Cytokine

Small proteins released by cells that communicate with immune cells, influencing their activity and response.

Cytotoxic T-Cells

A type of T-lymphocyte that directly kill damaged, infected, or cancerous cells in the body.

Delayed Hypersensitivity

(type IV) T cell-mediated immune response against pathogens infiltrating interstitial tissues, causing cellular infiltrate

Early Induced Immune Response

includes antimicrobial proteins stimulated during the first several days of an infection

Effector T-Cells

immune cells with a direct, adverse effect on a pathogen efferent lymphatic vessels

Graft-Versus-Host Disease

in bone marrow transplants; occurs when the transplanted cells mount an immune response against the recipient

Granzyme

apoptosis-inducing substance contained in granules of NK cells and cytotoxic T cells

Heavy chain

larger protein chain of an antibody

Helper T-Cells (Th)

T cells that secrete cytokines to enhance other immune responses, involved in activation of both B and T cell

Histamine

vasoactive mediator in granules of mast cells and is the primary cause of allergies and anaphylactic shock

IgA

antibody whose dimer is secreted by exocrine glands, is especially effective against digestive and respiratory pathogens, and can pass immunity to an infant through breastfeeding

IgD

class of antibody whose only known function is as a receptor on naive B cells; important in B cell activation

IgE

antibody that binds to mast cells and causes antigen-specific degranulation during an allergic response

IgG

main blood antibody of late primary and early secondary responses; passed from carrier to unborn child via placenta

IgM

antibody whose monomer is a surface receptor of naive B cells; the pentamer is the first antibody made blood plasma during primary responses

Immediate Hypersensitivity

(type I) IgE-mediated mast cell degranulation caused by crosslinking of surface IgE by antigen

Immune System

series of barriers, cells, and soluble mediators that combine to response to infections of the body with pathogenic organisms

Immunoglobulin

protein antibody; occurs as one of five main classes

Immunological Memory

ability of the adaptive immune response to mount a stronger and faster immune response upon re-exposure to a pathogen

Inflammation

basic innate immune response characterized by heat, redness, pain, and swelling

Innate Immune Response

rapid but relatively nonspecific immune response

Interferons

early induced proteins made in virally infected cells that cause nearby cells to make antiviral proteins

Light Chain

small protein chain of an antibody

Lymph

fluid contained within the lymphatic system

Lymph Node

one of the bean-shaped organs found associated with the lymphatic vessels

Lymphatic Capillaries

smallest of the lymphatic vessels and the origin of lymph flow

Lymphatic System

network of lymphatic vessels, lymph nodes, and ducts that carries lymph from the tissues and back to the bloodstream.

Lymphatic Trunks

large lymphatics that collect lymph from smaller lymphatic vessels and empties into the blood via lymphatic ducts

Lymphocytes

white blood cells characterized by a large nucleus and small rim of cytoplasm

Lymphoid nodules

unencapsulated patches of lymphoid tissue found throughout the body

Macrophage

ameboid phagocyte found in several tissues throughout the body

Macrophage Oxidative Metabolism

metabolism turned on in macrophages by T cell signals that help destroy intracellular bacteria

Major Histocompatibility Complex (MHC)

gene cluster whose proteins present antigens to T cells

Mast Cell

cell found in the skin and the lining of body cells that contains cytoplasmic granules with vasoactive mediators such as histamine

Memory T-Cells

long-lived immune cell reserved for future exposure to a pathogen

MHC Class I

found on most cells of the body, it binds to the CD8 molecule on T cells

MHC Class II

found on macrophages, dendritic cells, and B cells, it binds to CD4 molecules on T cells

MHC Polygeny

multiple MHC genes and their proteins found in body cells

Monocyte

precursor to macrophages and dendritic cells seen in the blood

Mucosa-Associated Lymphoid Tissue (MALT)

lymphoid nodule associated with the mucosa

Natural Killer Cell (NK)

cytotoxic lymphocyte of innate immune response

Naïve Lymphocyte

mature B or T cell that has not yet encountered antigen for the first time

Negative Selection

selection against thymocytes in the thymus that react with self-antigen

Neutralization

inactivation of a virus by the binding of specific antibody

Neutrophil

phagocytic white blood cell recruited from the bloodstream to the site of infection via the bloodstream

Opsonization

enhancement of phagocytosis by the binding of antibody or antimicrobial protein

Passive Immunity

transfer of immunity to a pathogen to an individual that lacks immunity to this pathogen usually by the injection of antibodies

Pattern Recognition Receptor (PRR)

leukocyte receptor that binds to specific cell wall components of different bacterial species

Perforin

molecule in NK cell and cytotoxic T cell granules that form pores in the membrane of a target cell

Peripheral Tolerance

mature B cell made tolerant by lack of T cell help

Phagocytosis

movement of material from the outside to the inside of the cells via vesicles made from invaginations of the plasma membrane

Plasma Cell

differentiated B cell that is actively secreting antibody

Polyclonal Response

response by multiple clones to a complex antigen with many determinants

Positive Selection

selection of thymocytes within the thymus that interact with self, but not non-self, MHC molecules

Primary Adaptive Response

immune system’s response to the first exposure to a pathogen

Primary Lymphoid Organ

site where lymphocytes mature and proliferate; red bone marrow and thymus gland

Regulatory T-Cells (Treg)

(also, suppressor T cells) class of CD4 T cells that regulates other T cell responses

Right Lymphatic Duct

drains lymph fluid from the upper right side of body into the right subclavian vein

Secondary Adaptive Response

immune response observed upon re-exposure to a pathogen, which is stronger and faster than a primary response

Secondary Lymphoid Organs

sites where lymphocytes mount adaptive immune responses; examples include lymph nodes and spleen

Sensitization

first exposure to an antigen

Spleen

secondary lymphoid organ that filters pathogens from the blood (white pulp) and removes degenerating or damaged blood cells (red pulp)

T-Cell

lymphocyte that acts by secreting molecules that regulate the immune system or by causing the destruction of foreign cells, viruses, and cancer cells

T-Cell Tolerance

process during T cell differentiation where most T cells that recognize antigens from one’s own body are destroyed

T-Cell-Dependent Antigen

antigen that binds to B cells, which requires signals from T cells to make antibody

T-Cell-Independent Antigen

binds to B cells, which do not require signals from T cells to make antibody

Th1 Cells

cells that secrete cytokines that enhance the activity of macrophages and other cells

Th2 Cells

cells that secrete cytokines that induce B cells to differentiate into antibody-secreting plasma cells

Thoracic Duct

large duct that drains lymph from the lower limbs, left thorax, left upper limb, and the left side of the head

Thymus

primary lymphoid organ; where T lymphocytes proliferate and mature

Tissue Typing

typing of MHC molecules between a recipient and donor for use in a potential transplantation procedure

Tonsils

lymphoid nodules associated with the nasopharynx

Type I Hypersensitivity

immediate response mediated by mast cell degranulation caused by the crosslinking of the antigen-specific IgE molecules on the mast cell surface