Comprehensive Guide to Innate and Adaptive Immunity Systems

What is the primary function of the immune system?

To differentiate self from nonself and neutralize pathogenic organisms or substances.

What are the three main strategies the immune system uses to handle pathogens?

Kill, repel, and expel pathogens.

What is the primary role of the innate immune system?

To act as the first line of defense by providing nonspecific, immediate protection against a wide range of pathogens.

How does the response time of innate immunity compare to adaptive immunity?

Innate immunity is immediate (minutes to hours), while adaptive immunity is delayed (days) upon first exposure.

What is the difference in specificity between innate and adaptive immunity?

Innate immunity is non-specific and recognizes common microbial patterns, whereas adaptive immunity is highly specific and recognizes unique antigens.

Which system possesses immunological memory?

The adaptive immune system.

What are the main cell types involved in the innate immune system?

Neutrophils, macrophages, dendritic cells, and NK cells.

What are the major mechanisms of the innate immune system?

Phagocytosis, inflammation, complement, and NETs.

How does the innate immune system recognize pathogens?

Through pattern recognition receptors (PRRs) that detect common microbial molecules.

What are the primary recognition receptors for the adaptive immune system?

Antigen receptors, specifically BCRs and TCRs.

What is the function of a neutrophil?

To seek out, capture, and kill bacterial pathogens through phagocytosis.

What are the three layers of the skin?

The epidermis is the top layer, followed by the dermis and hypodermis (implied as the 3 layers).

What protein makes the epidermis mechanically tough?

Keratin.

Why is the skin an effective physical barrier against microbes?

It is dry, cool, salty, acidic due to fatty acids, and the outer layer is shed frequently.

What is the function of sebum?

It is an oil produced by sebaceous glands that physically blocks bacteria from invading sweat glands.

What is oleic acid's role in innate immunity?

It is a chemical mediator produced by the microbiome that helps inhibit microbial colonization.

What are chemical mediators?

Substances found in bodily fluids and tissues that inhibit microbial colonization and infection.

Do innate and adaptive immunity function independently?

No, they function as an integrated system that communicates to coordinate an effective immune response.

What is the main role of adaptive immunity?

To provide targeted, long-term protection.

What are the major mechanisms of adaptive immunity?

Antibody production and cytotoxic T cell killing.

What happens to the microbes on the surface of the skin when the outer layer is shed?

They are shed along with the dead skin cells.

Why is the innate immune system considered 'nonspecific'?

It does not target a specific pathogen but defends against a wide range of potential pathogens using common patterns.

What is the primary function of skin acidity?

It makes the surface inhospitable to many pathogenic microbes.

What enzyme in saliva and tears breaks down bacterial peptidoglycan?

Lysozyme.

How does the female reproductive system inhibit pathogen growth?

Lactobacilli produce lactic acid, which lowers the pH.

What is the function of cerumen in the ears?

It contains fatty acids that maintain an acidic pH to inhibit microbes.

What are the primary components of mucus?

Mucins (glycoproteins) and antimicrobial molecules like lysozyme, defensins, and antibodies.

What is mucociliary clearance?

The process where mucus traps microbes and cilia move them out of the respiratory tract.

What is the function of sebum and oleic acid on the skin?

They provide an oil barrier and lower the pH to inhibit pathogens.

How do lactoferrin and transferrin inhibit bacterial growth?

They bind and sequester iron.

What is the role of primary lymphoid organs?

They are the sites of immune cell development.

Where are all blood and immune cells produced?

In the bone marrow through hematopoiesis.

What is the function of the thymus?

It is the site where T cells mature.

What is thymus involution?

The process where the thymus gradually shrinks with age.

What is the primary function of lymph nodes?

They filter lymph fluid and allow immune cells to detect pathogens.

What is the role of the spleen in the immune system?

It filters blood and removes pathogens and damaged cells.

What are Peyer's patches?

Lymphoid tissues in the small intestine that monitor microbes entering via the digestive tract.

What are the two lineages derived from hematopoietic stem cells?

Myeloid cells and lymphoid cells.

Which cells differentiate from lymphoid stem cells?

B cells, T cells, and natural killer cells.

What is another name for polymorphonuclear leukocytes (PMNs)?

Granulocytes.

What are the three types of granulocytes?

Neutrophils, eosinophils, and basophils.

What are the four key functions of neutrophils?

Chemotaxis, killing with toxic chemicals, phagocytosis, and trapping pathogens in NETs.

What is a phagolysosome?

A structure formed by the fusion of a phagosome with a lysosome to digest a pathogen.

What are Neutrophil Extracellular Traps (NETs)?

Web-like lattices of DNA coated with antimicrobial proteins used to trap and kill pathogens.

What is NETosis?

The process by which neutrophils release their DNA to form NETs.

How do some pathogens like Neisseria gonorrhoeae escape NETs?

They produce nucleases that degrade the DNA in the traps.

What clinical condition is linked to excessive NET formation?

Autoimmune diseases such as systemic lupus erythematosus.

What is the function of platelets (thrombocytes)?

Blood clotting and tissue repair.

What is the primary consequence of neutrophil dysfunction?

Increased susceptibility to recurrent bacterial and fungal infections.

What is the underlying defect in Chronic Granulomatous Disease (CGD)?

Neutrophils cannot generate the reactive oxygen species required to kill microbes.

What characterizes Leukocyte Adhesion Deficiency (LAD)?

Neutrophils fail to adhere to blood vessel walls or migrate to infection sites, resulting in little to no pus formation.

What is the primary defect in Chediak-Higashi syndrome?

Defective lysosomal trafficking that prevents proper microbial killing.

What is the clinical term for a low neutrophil count?

Neutropenia.

What is the primary function of eosinophils?

Defense against large parasites, such as helminths, and control of allergic inflammation.

How do eosinophils kill multicellular parasites?

By releasing toxic granule proteins like major basic protein and eosinophil peroxidase.

Which cytokines do eosinophils regulate to influence tissue repair and immune response?

IL-4, IL-5, and IL-13.

Where are basophils primarily found?

In the blood.

What is the function of histamine released by basophils?

It acts as a signaling molecule that causes vasodilation, increased vessel permeability, mucus production, bronchoconstriction, and itching.

What role do basophils play in the adaptive immune response?

They produce IL-4 and IL-13 to help initiate Th2 immune responses.

Where are mast cells primarily located?

In tissues such as the skin, lungs, gut, and areas near blood vessels.

What is Mast Cell Activation Syndrome (MCAS)?

A condition where mast cells release inflammatory mediators inappropriately, causing chronic allergic-like symptoms.

What is anaphylaxis in the context of mast cells?

A severe systemic activation of mast cells leading to rapid histamine release, vasodilation, swelling, and airway constriction.

What is the primary difference in lifespan between mast cells and basophils?

Mast cells are long-lived (weeks to months), while basophils are short-lived (days).

Which cell type is responsible for triggering immediate allergic reactions in tissues?

Mast cells.

Which cell type is considered a rare white blood cell (less than 1% of WBCs)?

Basophils.

What are the two primary cell types that monocytes differentiate into after migrating to tissues?

Macrophages and dendritic cells.

What are the four key functions of macrophages?

Phagocytosis, removal of dead cells/debris, release of cytokines, and antigen presentation.

What is antigen processing?

The process by which macrophages break down engulfed pathogens into smaller peptide fragments.

Why are macrophages classified as antigen-presenting cells (APCs)?

Because they display processed antigen fragments on their surface to activate T cells.

What is the role of activated T cells in the adaptive immune response?

They stimulate B cells to produce antibodies and can become cytotoxic T cells to destroy infected host cells.

How do mast cells and basophils differ in their role during an allergic reaction?

Mast cells trigger the immediate local response in tissues, while basophils help amplify the immune response in the blood.

What is the primary mediator released by both mast cells and basophils?

Histamine.

What is the result of mastocytosis?

An accumulation of excess mast cells in tissues, leading to symptoms like flushing, itching, and abdominal pain.

What are the primary functions of macrophages?

Phagocytosis, pathogen killing, inflammation, and coordination of immune responses.

What cytokines are produced by macrophages to recruit other immune cells?

TNF-a, IL-1, and IL-6.

What is the clinical consequence of Mycobacterium tuberculosis surviving inside macrophages?

Chronic infection and granuloma formation.

What characterizes Chronic Granulomatous Disease (CGD)?

A defect in the oxidative burst in phagocytes, leading to recurrent bacterial and fungal infections.

What occurs in Gaucher Disease regarding macrophages?

Lipid-filled macrophages accumulate in the liver, spleen, and bone marrow due to lysosomal dysfunction.

How do macrophages contribute to atherosclerosis?

They ingest excess cholesterol and become foam cells, contributing to plaque formation in arteries.

What is the primary role of dendritic cells in the immune system?

They act as professional antigen-presenting cells that connect the innate and adaptive immune systems.

How do dendritic cells differ from macrophages in their antigen uptake?

Dendritic cells take up small soluble antigens in addition to phagocytosing whole bacteria.

What is the consequence of dendritic cell dysfunction on T cells?

Impaired activation of naive T cells and weak adaptive immune responses.

What is the role of GATA2 in the immune system?

It is a genetic factor whose deficiency affects dendritic cells, monocytes, and NK cells, increasing infection and leukemia risk.

How do tumors evade the immune system via dendritic cells?

Tumors may suppress dendritic cell activity to prevent effective anti-tumor T cell responses.

What are the structural characteristics of platelets?

They are small fragments that lack a nucleus and develop from megakaryoblasts.

What is the process of blood clot formation involving platelets?

Platelets stick to damaged endothelial cells, clump together, and are trapped by fibrin.

What are petechiae?

Small red or purple spots on the skin caused by capillary bleeding.

What is Immune Thrombocytopenic Purpura (ITP)?

An autoimmune disorder characterized by the destruction of platelets.

What is the difference between Bernard-Soulier Syndrome and Glanzmann Thrombasthenia?

Bernard-Soulier affects platelet adhesion, while Glanzmann Thrombasthenia prevents proper platelet aggregation.

Which cells arise from lymphoid stem cells?

B cells, T cells, and natural killer (NK) cells.

Where do B cells and T cells undergo final maturation?

B cells mature in the bone marrow, and T cells mature in the thymus.

What are the primary targets of Natural Killer (NK) cells?

Virus-infected cells and tumor cells.

What are the two main ways NK cells recognize their targets?

By detecting missing self molecules or identifying antibodies attached to host cells.

What is the function of MHC I molecules?

They act as a 'self-maker' signal that tells NK cells not to attack a cell.

What happens when an NK cell encounters a cell with MHC I?

The NK cell detects the self signal and does not attack the cell.

What triggers an NK cell to attack a host cell?

The loss of MHC I molecules on the surface of the host cell.

What is the role of platelets in innate defense?

They release antimicrobial peptides and can trigger NET formation in neutrophils.

Why is sepsis considered a consequence of macrophage dysfunction?

Dysregulated cytokine release can cause systemic inflammation and organ failure.

What two conditions trigger an NK cell attack on a host cell?

The cell lacks MHC I markers and displays activating signals.

What is the function of perforin released by NK cells?

It creates pores in the target cell membrane.