Immuno 1 Flashcards

What is the main physiologic function of the immune system?

A. Regulate blood pressure

B. Prevent infection and cancer

C. Maintain glucose levels

D. Produce red blood cells

Which two major forms of immunity protect the body?

A. Innate and adaptive

B. Humoral and inflammatory

C. Cellular and passive

D. Natural and acquired antibodies

Which description best characterizes innate immunity?

A. Develops only after vaccination

B. Requires lymphocyte proliferation

C. Provides early ready-made defense

D. Produces long-term immune memory

Which lymphocyte is part of innate immunity?

A. Helper T cell

B. Plasma cell

C. Memory B cell

D. Natural killer cell

Natural killer cells primarily provide rapid defense by doing what?

A. Killing infected cells

B. Producing antibodies

C. Presenting peptide antigens

D. Forming memory cells

What are the two major cellular reactions of innate immunity?

A. Opsonization and neutralization

B. Inflammation and antiviral defense

C. Memory and differentiation

D. Humoral and cellular immunity

During innate immunity, what primarily induces inflammation?

A. Antibodies

B. Memory cells

C. Cytokines

D. T-cell receptors

Which components are central to innate antiviral defense?

A. B cells and antibodies

B. Neutrophils and complement

C. T cells and macrophages

D. Type I IFNs and NK cells

What activates lymphocytes during adaptive immune responses?

A. Microbial antigens

B. Host hormones

C. Plasma proteins

D. Clotting factors

After microbial antigen stimulation, lymphocytes undergo which changes?

A. Degranulation and phagocytosis

B. Proliferation and differentiation

C. Vasodilation and migration

D. Opsonization and lysis

Activated lymphocytes generate which two important cell populations?

A. Macrophages and neutrophils

B. Basophils and eosinophils

C. Effector and memory cells

D. Platelets and erythrocytes

What is the main function of adaptive immune effector cells?

A. Produce inflammatory edema

B. Store microbial antigens

C. Maintain immune tolerance

D. Eliminate microbes

Why are memory cells important during later microbial exposures?

A. They respond more effectively

B. They suppress all inflammation

C. They eliminate antigen specificity

D. They replace innate immunity

Which cells are responsible for adaptive immunity?

A. Neutrophils

B. Lymphocytes

C. Platelets

D. Mast cells

Which immunological feature uniquely distinguishes adaptive lymphocytes (T and B cells) from innate immune cells?

A. Secretion of signaling cytokines

B. Migration between blood and peripheral tissues

C. Clonally distributed antigen receptors generated by somatic recombination

D. Circulation within systemic blood vessels

The ability to distinguish millions of different antigens is called what?

A. Memory

B. Tolerance

C. Proliferation

D. Specificity

Which cells mediate humoral immunity?

A. B lymphocytes

B. T lymphocytes

C. Natural killer cells

D. Macrophages

Humoral immunity primarily eliminates which targets?

A. Intracellular microbes and toxins

B. Extracellular microbes and toxins

C. Host tumor cells and extracellular toxins

D. Infected host cells and intracellular toxins

Which cells mediate immunity against intracellular microbes?

A. B lymphocytes

B. Natural killer cells

C. T lymphocytes

D. Plasma cells

Which statement correctly compares B- and T-cell antigen recognition?

A. Both recognize only proteins

B. T cells recognize carbohydrates directly

C. B cells recognize displayed peptides

D. T cells recognize displayed peptides

A patient develops immunity after recovering from an infection. What type of immunity is this?

A. Passive immunity

B. Active immunity

C. Innate immunity

D. Tolerant immunity

A patient develops immunity after receiving a vaccine. What type of immunity is produced?

A. Active immunity

B. Passive immunity

C. Innate immunity

D. Maternal immunity

A newborn receives protective antibodies through breast milk. What type of immunity is this?

A. Active immunity

B. Adaptive tolerance

C. Passive immunity

D. Clonal immunity

Passive immunity results from transfer of what?

A. Antibodies or lymphocytes

B. Neutrophils or macrophages

C. Platelets or erythrocytes

D. Cytokines or complement

According to the clonal selection theory, when are antigen-specific lymphocyte clones (with unique surface receptors) generated in the body?

A. Only following exogenous antigen presentation or vaccination

B. Prior to any exposure to foreign antigen

C. Concurrently during the effector phase of antigen elimination

D. Exclusively during the differentiation of long-lived memory cells

Central to Burnet’s _____ selection theory is the principle that lymphocyte diversity is generated _____ and prior to antigen encounter via V(D)J recombination in primary lymphoid organs (bone marrow and thymus). Antigen exposure merely selects and expands an already-existing clone.

How does an antigen initiate a specific adaptive immune response?

A. Activates every lymphocyte equally

B. Suppresses all lymphocyte clones

C. Selects its specific lymphocyte clone

D. Converts neutrophils into lymphocytes

What occurs during clonal expansion after lymphocyte activation?

A. Activated lymphocytes proliferate

B. Lymphocytes undergo immediate apoptosis

C. Antigens become self antigens

D. Memory cells disappear

Clonal expansion can generate approximately what?

A. Several unrelated lymphocytes

B. Thousands of clonal progeny

C. Only one effector cell

D. Mostly innate immune cells

The host's own potentially antigenic molecules are called what?

A. Foreign antigens

B. Microbial epitopes

C. Self antigens

D. Clonal antigens

What term describes immune unresponsiveness to self antigens?

A. Immunological tolerance

B. Clonal expansion

C. Active immunity

D. Antigen elimination

Which cells mediate the immune response to first antigen exposure?

A. Memory lymphocytes

B. Effector macrophages

C. Naive lymphocytes

D. Plasma proteins

Which cells are activated during a secondary immune response?

A. Naive lymphocytes

B. Memory lymphocytes

C. Neutrophils

D. Mast cells

From which precursor cell population do long-lived memory lymphocytes directly originate during an adaptive immune response?

A. Progeny of naive lymphocytes activated by specific antigen exposure

B. Circulating myeloid lineage neutrophil precursors

C. Tissue-resident macrophage populations

D. Parenchymal hepatocyte populations

What happens to memory-cell numbers after repeated microbial encounters?

A. They progressively decline

B. They remain unchanged

C. They become naive cells

D. More memory cells are generated

Which feature allows memory cells to support long-term immunity?

A. They require constant antigen

B. They survive without antigen

C. They rapidly become neutrophils

D. They continuously secrete complement

What is the correct first step of the adaptive immune response?

A. Antigen elimination

B. Lymphocyte activation

C. Antigen recognition

D. Contraction

After antigen elimination, what phase reduces the expanded lymphocyte population?

A. Memory

B. Contraction by apoptosis

C. Clonal selection

D. Antigen recognition

Which three principal cell groups participate in adaptive immune responses?

A. Lymphocytes, APCs, effector cells

B. Neutrophils, platelets, erythrocytes

C. Mast cells, basophils, eosinophils

D. Fibroblasts, myocytes, endothelial cells

What are lymphocyte-specific surface proteins called?

A. MHC molecules

B. CD molecules

C. Fc receptors

D. Cytokine receptors

Which cells are the only antibody-producing lymphocytes?

A. B lymphocytes

B. T lymphocytes

C. NK cells

D. Macrophages

How do B lymphocytes directly recognize antigens?

A. Through secreted cytokines

B. Through MHC molecules

C. Through complement receptors

D. Through membrane antibodies

What directly activates a B lymphocyte?

A. Cytokine degradation

B. MHC destruction

C. Antigen binding membrane antibody

D. Neutrophil migration

What happens to B lymphocytes after activation?

A. They undergo proliferation

B. They become neutrophils

C. They lose antigen receptors

D. They stop dividing

Activated B-cell progeny can differentiate into what?

A. Macrophages

B. Plasma cells

C. Neutrophils

D. Dendritic cells

What are the effector cells of B-cell lineage?

A. Memory T cells

B. Helper T cells

C. Plasma cells

D. Natural killer cells

Where do plasma cells primarily remain?

A. Blood and skin

B. Lymphoid organs and marrow

C. Liver and kidney

D. Lung and intestine

After plasma cells secrete antibodies, where do antibodies go?

A. Into circulation

B. Into thymic cortex

C. Into bone matrix

D. Into intracellular vesicles

Polysaccharide and lipid antigens mainly stimulate which antibody?

A. IgG

B. IgA

C. IgE

D. IgM

Helper T cells can improve antibody binding strength through what process?

A. Affinity maturation

B. Clonal deletion

C. Antigen presentation

D. Class suppression

What changes during affinity maturation?

A. Antibody quantity increases

B. Antibody affinity increases

C. Antigen size decreases

D. MHC expression decreases

What type of antigen do T cells recognize?

A. Free bacterial lipids

B. Soluble polysaccharides

C. Intact extracellular proteins

D. Displayed peptide fragments

Which molecules display protein-derived peptides to T cells?

A. CD molecules

B. Fc receptors

C. MHC molecules

D. Immunoglobulins

What is another name for CD4+ T cells?

A. Helper T cells

B. Cytotoxic T cells

C. Regulatory B cells

D. Plasma cells

How do helper T cells assist humoral immunity?

A. Kill extracellular bacteria directly

B. Help B cells make antibodies

C. Produce membrane antibodies

D. Form complement proteins

How do helper T cells assist phagocytes?

A. Suppress microbial ingestion

B. Block cytokine release

C. Destroy phagocytes

D. Help destroy ingested microbes

Which molecules do helper T cells secrete to activate immune cells?

A. Antibodies

B. Complement proteins

C. Cytokines

D. Peptidoglycans

A T lymphocyte directly kills a host cell containing cytoplasmic microbes. Which lymphocyte is responsible?

A. CD8+ cytotoxic T cell

B. CD4+ regulatory T cell

C. Naive B lymphocyte

D. Plasma cell

What is another name for a CD8+ T cell?

A. Helper T lymphocyte

B. Regulatory T lymphocyte

C. Cytotoxic T lymphocyte

D. Plasma cell

Which target is eliminated by cytotoxic T lymphocytes?

A. Free extracellular toxins

B. Cells harboring intracellular microbes

C. Circulating antibodies

D. Soluble microbial antigens

Regulatory T lymphocytes belong to which T-cell category?

A. CD8+ cells

B. Plasma cells

C. Naive B cells

D. CD4+ cells

What is the main function of regulatory T lymphocytes?

A. Limit immune responses

B. Secrete antibodies

C. Kill infected cells

D. Capture microbial antigens

A lymphocyte has an antigen receptor but cannot yet eliminate antigen. What type is it?

A. Effector lymphocyte

B. Naive lymphocyte

C. Plasma cell

D. Regulatory lymphocyte

What must happen before a naive lymphocyte becomes an effector cell?

A. It must lose receptors

B. It must enter marrow

C. It must recognize antigen

D. It must secrete antibodies

Besides antigen recognition, naive lymphocyte activation requires what?

A. Microbe-induced additional signals

B. Antibody secretion

C. Complement activation

D. Plasma-cell differentiation

After activation, naive lymphocytes first undergo what major process?

A. Apoptosis

B. Proliferation

C. Phagocytosis

D. Degranulation

Activated naive lymphocytes can differentiate into which two populations?

A. Neutrophils and macrophages

B. Plasma and dendritic cells

C. Effector and memory cells

D. Regulatory and epithelial cells

What happens to naive lymphocytes that remain unactivated for weeks to months?

A. They become plasma cells

B. They become macrophages

C. They remain indefinitely

D. They die and are replaced

What is the primary function of effector cells?

A. Eliminate microbes

B. Maintain tolerance

C. Store antigens

D. Produce naive lymphocytes

Effector lymphocytes arise directly from what?

A. Dendritic cells

B. Differentiated naive-cell progeny

C. Tissue macrophages

D. Regulatory T cells

What distinguishes effector lymphocytes from naive lymphocytes?

A. They lack antigen receptors

B. They remain only in marrow

C. They produce antigen-eliminating molecules

D. They cannot enter tissues

Where do effector T lymphocytes travel after activation?

A. Bone marrow

B. Peripheral infection sites

C. Thymic cortex

D. Blood

What happens to effector T cells after antigen elimination?

A. They become macrophages

B. They remain permanently active

C. They die

D. They become plasma cells

What is a major function of antigen-presenting cells?

A. Capture and display microbial antigens

B. Secrete antibodies into circulation

C. Kill cytoplasmic microbes directly

D. Suppress all T-cell responses

Which cells are listed as antigen-presenting cells?

A. Neutrophils and eosinophils

B. B cells and plasma cells

C. Mast cells and basophils

D. Dendritic cells and macrophages

What distinguishes a professional antigen-presenting cell from a cell that only displays antigen?

A. It also provides activating signals

B. It secretes antibodies

C. It destroys all microbes

D. It produces complement

Which cells are directly activated by dendritic cells?

A. B lymphocytes

B. T lymphocytes

C. Neutrophils

D. Mast cells

Which signal provided by dendritic cells works together with antigen to activate T cells?

A. Costimulation

B. Histamine

C. Antibody

D. Heparin

Besides antigen and costimulation, what else supports T-cell proliferation and differentiation?

A. Platelets

B. Cytokines

C. Erythrocytes

D. Fibrin

Where are follicular dendritic cells located?

A. Thymic cortex

B. Bone marrow

C. Germinal centers

D. Blood vessels

What do follicular dendritic cells display in germinal centers?

A. Cytokines

B. Antigens

C. Antibodies

D. Complement only

Antigen displayed by follicular dendritic cells stimulates differentiation of which cells?

A. T cells

B. Neutrophils

C. B cells

D. Macrophages

Most immune cells originate from progenitors located where?

A. Bone marrow

B. Thymus

C. Spleen

D. Lymph nodes

Most immune cells are broadly divided into which two groups?

A. Innate and adaptive

B. Myeloid and lymphoid

C. Humoral and cellular

D. Mature and immature

Which cells belong to the myeloid lineage?

A. Neutrophils and macrophages

B. B cells and T cells

C. Plasma cells and lymphocytes

D. Helper and cytotoxic cells

Which antigen-presenting cell is classified as myeloid?

A. Plasma cell

B. Dendritic cell

C. B lymphocyte

D. T lymphocyte

Which additional immune cell belongs to the myeloid group?

A. Mast cell

B. Memory B cell

C. Helper T cell

D. Plasma cell

What is the main function of generative lymphoid organs?

A. Initiate inflammation

B. Produce mature lymphocytes

C. Destroy extracellular microbes

D. Secrete antibodies

What is the main role of secondary lymphoid organs?

A. Produce erythrocytes

B. Mature neutrophils

C. Allow lymphocytes to meet antigens

D. Store platelets

Where are lymphocytes and APCs organized to initiate immune responses?

A. Secondary lymphoid organs

B. Bone cortex

C. Skeletal muscle

D. Renal tissue

Which site is a secondary lymphoid organ?

A. Bone marrow

B. Lymph node

C. Thymus

D. Liver

Which body-wide immune system is classified as secondary lymphoid tissue?

A. Cutaneous immune system

B. Endocrine system

C. Cardiovascular system

D. Renal system

Which immune system protects mucosal surfaces and functions as secondary lymphoid tissue?

A. Reticuloendothelial system

B. Mucosal immune system

C. Complement system

D. Coagulation system

At which sites are adaptive immune responses primarily initiated and developed?

A. Generative lymphoid organs

B. Secondary lymphoid organs

C. Bone marrow only

D. Thymus only

Which description best defines a lymph node?

A. Diffuse collection of circulating leukocytes

B. Encapsulated aggregate of lymphoid tissue

C. Vascular reservoir of blood cells

D. Primary site of erythrocyte production

Where are lymph nodes distributed throughout the body?

A. Along major arteries

B. Within bone marrow cavities

C. Around peripheral nerves

D. Along lymphatic channels

Within a lymph node, B lymphocytes are concentrated in what structures?

A. Follicles

B. Sinusoids

C. Medullary cords

D. High endothelial venules

Where are B-cell follicles located within lymph nodes?

_____

What keeps B lymphocytes attracted to and retained within follicles?

A. Chemokines

B. Antibodies

C. Complement proteins

D. Cytokines

Which chemokine receptor on B cells promotes migration into follicles?

A. CCR7

B. CD4

C. CXCR5

D. CD8

Which cells provide chemokine signals recognized by B-cell CXCR5?

A. Macrophages

B. Follicular dendritic cells

C. Neutrophils

D. Helper T cells

A lightly staining central region appears within an activated B-cell follicle. What is it?

A. Paracortex

B. Medullary sinus

C. Hilum

D. Germinal center

Under which condition is a germinal center most likely to form in the secondary lymphoid organs?

A. Following T-cell–dependent antigen activation of B cells

B. Prior to initial antigen exposure in naive B cells

C. During acute neutrophil recruitment in early innate inflammation

D. During erythropoiesis and erythrocyte maturation in the bone marrow

Formation of a germinal center requires B cells to receive signals from whom?

A. Helper T cells

B. Neutrophils

C. Natural killer cells

D. Basophils

Where are T lymphocytes and dendritic cells concentrated within lymph nodes?

_____

Which chemokine receptor helps draw T cells into lymphoid organs?

A. CXCR5

B. CCR7

C. CD25

D. FcεRI

Naive T lymphocytes mature in which organ before entering circulation?

A. Bone marrow

B. Spleen

C. Thymus

D. Lymph node

How do naive T cells enter lymph nodes from blood?

A. Through lymphatic capillaries

B. By phagocytosing endothelium

C. By binding HEV molecules

D. Through splenic sinusoids

What type of vessel allows naive lymphocytes to enter lymph nodes?

A. High endothelial venule

B. Muscular artery

C. Central vein

D. Lymphatic sinus

Where are high endothelial venules located within lymph nodes?

A. Medullary cords

B. Germinal centers

C. Lymphatic follicles

D. Parafollicular cortex

Naive lymphocytes continuously circulate between blood and what?

A. Bone marrow

B. Secondary lymphoid organs

C. Peripheral infection sites

D. Thymus

After activation in lymphoid tissue, where do effector lymphocytes migrate?

A. Bone marrow

B. Thymus

C. Sites of infection

D. Germinal centers only

The spleen primarily mounts immune responses against what?

A. Blood-borne antigens

B. Lymph-borne antigens

C. Skin-bound antigens

D. Bone marrow antigens