jess review

What is immunology?

The study of how a host or person responds to foreign substances and infectious agents.

What is an antigen (Ag)?

A foreign substance recognized by the immune system that can react with an antibody or sensitized T cell.

What is an antibody (Ab)?

A specific immunoglobulin produced by activated B cells in response to an antigen.

What is immunity?

The condition in which the body is resistant to infection or disease.

What is humoral immunity?

Antibody-mediated immunity; it depends mainly on B lymphocytes and the antibodies they produce.

What is cell-mediated immunity?

Immunity mediated by T lymphocytes and their effects on infected, abnormal, or foreign cells.

How is an immunogen different from an antigen?

An antigen can be recognized/react with immune products; an immunogen is an antigen capable of actively triggering an immune response.

What was variolation?

Deliberate exposure to material from smallpox lesions in hopes of producing protection against smallpox.

What did Edward Jenner observe?

People who had contracted cowpox were generally protected from smallpox.

What is cross-immunity?

Protection against one antigen produced by exposure to a related antigen.

What is vaccination?

Introducing infectious or antigenic material to stimulate immunity.

What is attenuation?

Weakening or modifying an infectious agent, such as by heat, aging, or chemical treatment, so it has reduced virulence but can stimulate immunity.

Who is credited with developing the first attenuated vaccine?

Louis Pasteur.

What are the key characteristics of innate immunity?

It is present at birth, nonspecific, does not require previous exposure, and acts as the body's first line of defense.

What are the key characteristics of adaptive immunity?

It develops after antigen exposure, is directed toward a particular antigen/pathogen, and has specificity and immunologic memory.

What are the two major arms of adaptive immunity?

Humoral immunity (B cells/antibodies) and cell-mediated immunity (T cells).

Give examples of external innate defenses.

Unbroken skin, mucous membranes, sweat, skin oils, acidic skin pH, respiratory mucus/cilia, urinary flushing, acidic urine, vaginal acidity, stomach acid, lysozyme, and normal flora.

How does normal flora protect the body?

It occupies attachment sites and competes with pathogens for nutrients and space.

What does lysozyme do and where is it found?

It is an antibacterial enzyme found in tears and saliva.

What do internal defenses do?

They act after an organism enters the body; examples include WBCs, phagocytosis, acute phase reactants, antibodies, and complement.

What are the two major properties of a complete antigen?

Immunogenicity (ability to stimulate an immune response) and reactivity (ability to react with products of that response).

What factors influence the strength of an immune response?

Age, health status, antigen dose, route of inoculation, genetics, foreignness, molecular size, chemical complexity, and processability.

Which types of molecules are usually strong antigens?

Proteins are usually strong antigens because they are large and structurally complex; polysaccharides are also often effective antigens.

What is an epitope?

The small portion of an antigen recognized by a B cell, antibody, or T cell; also called an antigenic determinant.

Why is epitope shape important?

Immune receptors must fit the epitope.

What is valence?

The number of antigenic determinants or antibody-binding sites available on an antigen.

What is a hapten?

A small molecule that usually cannot stimulate an immune response by itself.

What must happen for a hapten to become immunogenic?

It must attach to a larger carrier molecule.

A small molecule can bind antibody but cannot stimulate an immune response alone. What is it?

A hapten.

What is an autoantigen?

An antigen belonging to the person's own body.

What is an alloantigen?

An antigen from another person of the same species.

What is a heteroantigen?

An antigen from a different species.

What are heterophile antigens?

Identical or very similar antigens between different species that can cause cross-reactions.

What is an adjuvant?

A substance added to an antigen or vaccine to strengthen the immune response.

What are acute phase reactants?

Serum substances whose concentrations change during infection, injury, trauma, or inflammation.

What are major functions of acute phase reactants?

Enhance phagocytosis, promote opsonization and inflammation, activate complement, limit tissue damage, support clotting/wound healing, and bind/remove damaging substances.

Which cytokines stimulate production of acute phase reactants?

IL-1 beta, IL-6, and TNF-alpha.

What is CRP and when does it rise?

C-reactive protein is a nonspecific acute inflammatory marker that rises rapidly with infection, inflammation, surgery, trauma, tissue injury, and other inflammatory conditions.

What does CRP do?

Promotes opsonization and agglutination, activates complement, binds phagocytes, and increases phagocytosis.

Why can't an elevated CRP identify a specific disease?

CRP is a nonspecific indicator that rises in many inflammatory conditions.

What can a falling CRP suggest?

Treatment may be effective or inflammation may be resolving.

What is the significance of high-sensitivity CRP?

An elevated hs-CRP is associated with increased myocardial infarction risk.

What is serum amyloid A?

An acute phase reactant produced mainly by the liver that rises during infection/inflammation and assists with cleanup of damaged tissue.

What are the major functions of complement?

Opsonization, chemotaxis, cell lysis, and promotion of inflammation.

What does mannose-binding protein do?

Acts as an opsonin by binding mannose-containing structures on bacteria, yeasts, and viruses.

What is the major function of alpha-1 antitrypsin (AAT)?

It inhibits proteolytic enzymes, especially elastase, thereby limiting tissue damage and protecting lung tissue.

Why can AAT deficiency contribute to emphysema?

Without enough AAT, elastase can damage alveolar tissue.

What does haptoglobin bind?

Free hemoglobin released during intravascular hemolysis.

Why is haptoglobin important?

It removes free hemoglobin that could damage tissues and promote oxidative injury.

What does fibrinogen do?

It is converted to fibrin during clotting; it strengthens wounds, supports healing, creates a barrier against bacterial entry, and promotes RBC aggregation.

What does ceruloplasmin do?

Transports copper and oxidizes iron from ferrous to ferric form.

Ceruloplasmin deficiency is associated with what disease?

Wilson disease.

What are the five major WBC types?

Neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

Which WBCs are granulocytes?

Neutrophils, eosinophils, and basophils.

Which granulocyte is especially effective at phagocytosis?

Neutrophil.

What is another name for a neutrophil?

Seg or polymorphonuclear neutrophil (PMN).

What is the typical nuclear appearance of a neutrophil?

Approximately 2–5 lobes.

What are primary neutrophil granules also called?

Azurophilic granules.

Name important contents of primary neutrophil granules.

Myeloperoxidase, elastase, proteinase 3, lysozyme, and other antimicrobial enzymes.

What do secondary neutrophil granules contain?

Collagenase, lactoferrin, lysozyme, and NADPH-related antimicrobial activity.

What is the marginating pool?

Neutrophils positioned near/attached to blood vessel walls rather than freely circulating.

What is the typical appearance of an eosinophil?

Bilobed nucleus with large orange-to-red-orange granules.

When are eosinophils commonly increased?

Allergic reactions and parasitic infections, especially helminths.

What are important eosinophil functions?

Help destroy parasites, participate in allergic inflammation, neutralize products of basophils/mast cells, and can perform limited phagocytosis.

What is the typical appearance of a basophil?

Coarse, deep blue or purple granules.

What important substances are stored in basophil granules?

Histamine, heparin, and eosinophil chemotactic factor A.

What does histamine do?

Causes blood vessel dilation and contracts smooth muscle.

What does heparin do?

Acts as an anticoagulant.

What does eosinophil chemotactic factor do?

Attracts eosinophils to the area.

Which immunoglobulin binds to basophil membranes during allergic reactions?

IgE.

What is the main immune role of basophils?

They help initiate and maintain immediate hypersensitivity reactions.

How are mast cells similar to basophils?

They bind IgE and release histamine, heparin, and other mediators during allergic/hypersensitivity reactions.

What happens to monocytes after they enter tissues?

They can become macrophages.

What are major macrophage functions?

Phagocytosis, destruction of intracellular parasites, removal of debris, antigen presentation to T cells, initiation of adaptive responses, and participation in inflammation/tissue cleanup.

What are macrophages called in the lungs?

Alveolar macrophages.

What are macrophages called in the liver?

Kupffer cells.

What are macrophages called in the brain?

Microglial cells.

What are macrophages called in connective tissue?

Histiocytes.

Why are dendritic cells important?

They phagocytize foreign material and present antigen fragments to helper T cells, linking innate recognition to adaptive activation.

Where are Langerhans cells found?

Skin and mucous membranes.

What do toll-like receptors recognize?

Molecular patterns associated with foreign organisms, helping initiate innate immune responses.

Define phagocytosis.

The process by which a cell surrounds, engulfs, digests, and removes foreign material.

What are the four main phases of phagocytosis?

1) Contact and engulfment, 2) phagosome formation, 3) phagolysosome formation, 4) digestion and exocytosis.

What is a phagosome?

An intracellular vesicle containing an engulfed particle.

How does a phagolysosome form?

Cytoplasmic granules and lysosomes fuse with the phagosome.

What is opsonization?

Coating a foreign antigen so phagocytes can recognize, attach to, and engulf it more easily.

Name important opsonins.

IgG antibodies, CRP, complement components, mannose-binding protein, and other acute phase reactants.

What happens during the respiratory/oxidative burst?

The phagocyte increases oxygen consumption and generates toxic oxygen products that kill engulfed microorganisms.

What is the oxidative-burst sequence emphasized in these notes?

NADP → NADPH → superoxide → hydrogen peroxide via superoxide dismutase → hypochlorite via myeloperoxidase plus chloride.

What bleach-like substance is produced during the oxidative burst?

Hypochlorite.

What are the four classic signs of inflammation?

Redness, swelling, heat, and pain.

Why does redness occur during inflammation?

Increased blood flow.

Why does swelling occur during inflammation?

Increased capillary permeability causes fluid and cells to move into tissues.

What causes heat during inflammation?

Increased blood flow and accumulation of immune cells.

What causes pain during inflammation?

Tissue swelling, inflammatory mediators, and local injury.

What does histamine do during acute inflammation?

Causes vasodilation and contributes to increased vascular permeability.

What are chemotaxins?

Chemical signals that direct WBCs toward an infection or injury.

What is diapedesis?

Movement of neutrophils and other WBCs through blood vessel walls into infected or injured tissue.

What is the primary cell in acute inflammation?

Neutrophil.

Put the key events of acute inflammation in order.

Injury/infection → mast-cell histamine release → vasodilation → increased blood flow → increased capillary permeability → fluid/WBC movement into tissue → chemotaxis → neutrophil diapedesis → macrophage activity → phagocytosis/cleanup.