The major histocompatibility complex (MHC) class I molecules present antigen to which cells?

Which antibody isotype crosses the placenta?

Which complement pathway is activated by antigen–antibody complexes?

Which cell type is most important for killing virally infected cells without prior sensitization?

Which immunoglobulin is the first antibody produced in a primary immune response?

Which cytokine is primarily responsible for T helper 1 (Th1) differentiation?

The spleen is the primary site for removal of which of the following?

Which of the following is a cell-surface marker characteristic of B lymphocytes?

Passive immunity can be obtained by which of the following?

Toll-like receptors (TLRs) are part of which immune system?

Which hypersensitivity reaction is mediated by immune complexes (antigen–antibody) deposited in tissues?

The process by which neutrophils move toward a site of infection in response to chemical signals is called:

Which molecule opsonizes pathogens to enhance phagocytosis?

Class switching in B cells from IgM to IgG requires help from which cell type?

Which immunoglobulin is secreted in mucosal secretions and provides mucosal immunity?

The central tolerance mechanism that eliminates self-reactive T cells during development occurs in the:

Which of the following cytokines is a major antiviral interferon produced by virally infected cells?

Herd immunity is best described as:

An immediate allergic reaction like anaphylaxis is mediated mainly by which antibody?

Which cell presents antigen to naïve T cells and is known as the professional antigen-presenting cell?

The Fc portion of an antibody is responsible for:

Which immunodeficiency is characterized by recurrent bacterial infections and very low B cell counts?

Which lab test measures cell-mediated immunity by injecting purified protein derivative (PPD)?

Which immune cell type is primarily involved in allergic responses and parasitic helminth infections?

Which receptor on T cells recognizes antigen presented by MHC molecules?

Live attenuated vaccines are least appropriate for which group?

Which enzyme is found in phagolysosomes and helps kill ingested microbes via respiratory burst?

Which immunoglobulin is a pentamer in its serum form and is efficient at activating complement?

Antigenic variation in pathogens is a mechanism to:

Which cell-surface molecule is required for T-cell co-stimulation provided by antigen-presenting cells?

Which glycoprotein on cytotoxic T lymphocytes induces apoptosis in target cells by binding to Fas?

Which of the following is a thymic epithelial cell product important for T-cell maturation?

Serum sickness is an example of which hypersensitivity type?

Which antibody is chiefly involved in sensitization of mast cells in allergic reactions?

DiGeorge syndrome is characterized by which of the following?

Antigen-presenting cells load peptides onto MHC class II molecules in which intracellular compartment?

The hallmark of chronic inflammation often includes which cell type?

Which molecule acts as a chemokine for neutrophils during acute inflammation?

Which immune mechanism provides specific recognition and memory?

Which antibody test is commonly used to detect recent infection by measuring IgM levels?

Which is the main function of regulatory T (Treg) cells?

Complement deficiency of C5–C9 predisposes to infections by which organism?

Which test measures specific antibody response to a vaccine antigen?

Anergy to common recall antigens suggests dysfunction of which immunity arm?

Which immunoglobulin is mainly responsible for opsonization and complement activation in early immune responses?

Which immune receptor recognizes bacterial lipopolysaccharide (LPS)?

Immune complex-mediated glomerulonephritis is most closely associated with which hypersensitivity?

Which molecule is the primary opsonin produced by the complement system?

Antibody-dependent cell-mediated cytotoxicity (ADCC) primarily involves which effector cells?

Which vitamin is crucial for normal immune function and acts as an antioxidant?

Which autoimmune disease is associated with autoantibodies against acetylcholine receptors?

What is the primary role of interferon-gamma (IFN-γ) in immunity?

Which vaccine type contains purified toxoid (inactivated toxin)?

Chronic granulomatous disease results from defect in which phagocyte function?

Which lymphoid organ is the site of B cell maturation and germinal center formation?

Which cell produces histamine and heparin and is involved in immediate allergic reactions?

Which structure separates the thoracic and abdominal cavities and is the primary muscle of inspiration?

The functional unit of gas exchange in the lung is the:

Normal partial pressure of oxygen (PaO2) in arterial blood at sea level is approximately:

The majority of carbon dioxide in blood is transported as:

Which law describes the inverse relationship between pressure and volume for gases?

At the alveolar level, gas diffusion is best described by which principle?

Which value represents normal tidal volume (approximate) in a healthy adult?

The oxygen–hemoglobin dissociation curve shifts to the right with which of the following?

Which muscle group is most active during forced expiration?

The primary chemoreceptors that respond to changes in PaCO2 are located in the:

Which value is the approximate normal respiratory rate in an adult at rest?

In emphysema, which change is typically seen in the lungs?

The majority of oxygen transported in blood is:

Which value approximates normal functional residual capacity (FRC) in an adult?

Hypoxemia with normal A–a gradient suggests which cause?

What does a high alveolar-arterial (A–a) gradient indicate?

The major muscle recruited during quiet inspiration is the:

Which gas law explains the partial pressure of a gas in a mixture?

In the oxygen-hemoglobin dissociation curve, a left shift indicates:

Pulmonary surfactant reduces surface tension and is produced by which cells?

Which of the following increases oxygen delivery to tissues?

Which value best describes the normal arterial PCO2 (PaCO2)?

The Bohr effect describes:

Which receptor senses arterial oxygen tension and contributes to ventilatory drive at low PaO2?

Ventilation-perfusion (V/Q) ratio is lowest in which lung region in an upright person?

In restrictive lung disease, which spirometric pattern is typical?

The primary function of type I pneumocytes is:

Which condition produces a right-to-left shunt causing severe hypoxemia that is difficult to correct with supplemental oxygen?

During exercise, which of the following occurs to meet increased metabolic demands?

Pulmonary embolism classically causes which initial gas exchange abnormality?

The equation for alveolar gas (PAO2) includes which of the following variables?

Which nerve provides motor innervation to the diaphragm?

Diffusing capacity for carbon monoxide (DLCO) is decreased in which condition?

Ventilation is most effectively increased by which of the following changes?

In obstructive lung disease, which spirometry finding is typical?

Hyperventilation leads to which acid-base disturbance?

The most important determinant of airway resistance in small airways is:

The spleen filters blood and removes senescent or damaged RBCs.

CD19 is a pan-B-cell marker used to identify B lymphocytes.

Transfer of IgG from mother to fetus or IgA via breast milk confers passive immunity.

TLRs are pattern recognition receptors of the innate immune system.

Type III hypersensitivity involves immune complex deposition and complement activation.

Chemotaxis describes directional migration of leukocytes toward chemical cues.

C3b binds microbes and promotes phagocytosis by phagocytes (opsonization).

T helper cells provide cytokines and CD40L signals necessary for isotype switching.

Secretory IgA is the dominant antibody in mucosal secretions.

Negative selection in the thymus removes strongly self-reactive T cells.

Type I interferons (IFN-α and IFN-β) have antiviral actions.

Herd immunity reduces transmission, protecting those who are not immune.

IgE bound to mast cells mediates type I hypersensitivity and anaphylaxis.

Dendritic cells are the most potent professional antigen-presenting cells.

The Fc region mediates effector functions like binding Fc receptors and activating complement.

Bruton's agammaglobulinemia causes absent B cells and low immunoglobulins, causing recurrent bacterial infections.

The tuberculin skin test assesses delayed-type (cell-mediated) hypersensitivity to TB antigens.

Eosinophils are prominent in parasitic infections and allergic inflammation.

The TCR recognizes peptide antigens displayed on MHC molecules.

Live attenuated vaccines are contraindicated in pregnancy due to theoretical risk to fetus.

NADPH oxidase generates reactive oxygen species in the respiratory burst to kill microbes.

IgM is pentameric in serum and activates complement efficiently via classical pathway.

Antigenic variation alters surface antigens to avoid recognition by host antibodies.

CD80/CD86 (B7) on APCs bind CD28 on T cells providing necessary co-stimulatory signals.

FasL on CTLs binds Fas on target cells to trigger apoptosis (Fas-mediated death).

AIRE expressed in thymic medullary epithelial cells promotes presentation of tissue antigens for negative selection.

Serum sickness results from immune complex deposition (type III hypersensitivity).

IgE binds to FcεRI on mast cells leading to degranulation upon antigen exposure.

DiGeorge (22q11.2 deletion) causes thymic aplasia leading to T-cell deficiency and hypocalcemia.

Exogenous antigens are processed in endosomes/lysosomes and loaded onto MHC II.

Chronic inflammation typically involves lymphocytes and macrophages.

IL-8 (CXCL8) is a major neutrophil chemoattractant.

Adaptive immunity (B and T cells) provides antigen-specific responses and memory.

IgM-specific ELISA indicates recent or acute infection.

Tregs (e.g., CD4+CD25+FOXP3+) suppress immune responses and help maintain tolerance.

Terminal complement (C5–C9) deficiency increases risk of Neisseria meningitidis infections.

Antibody titer (e.g., by ELISA) measures specific humoral response post-vaccination.

Anergy (lack of skin test reactivity) indicates impaired cell-mediated immunity (T cell).

IgM is effective at activating complement and opsonizing pathogens early in responses.

TLR4 recognizes LPS (with MD-2 and CD14) triggering innate immune responses.

Type III hypersensitivity causes immune complex deposition in glomeruli leading to GN.

C3b coats pathogens and functions as an opsonin to enhance phagocytosis.

NK cells recognize antibody-coated target cells via Fc receptors and kill them (ADCC).

Vitamin C supports immune cell function and acts as an antioxidant.

Dendritic cells express MHC II and co-stimulatory molecules to activate CD4+ T cells.

Fcγ receptors on phagocytes bind IgG Fc regions to enhance phagocytosis.

Boosters elicit a faster, higher-titer secondary immune response due to immunologic memory.

Myasthenia gravis involves autoantibodies against nicotinic ACh receptors at the neuromuscular junction.

IFN-γ activates macrophages and supports Th1-mediated cellular immunity.

Toxoid vaccines use inactivated bacterial toxins to provoke protective immunity.

CGD is due to defective NADPH oxidase, impairing the respiratory burst to kill microbes.

Secondary lymphoid organs (lymph nodes, spleen) host germinal centers where B cells proliferate and undergo affinity maturation.

Mast cells (and basophils) release histamine and heparin during type I hypersensitivity.

The diaphragm contracts to increase thoracic volume and drive inspiration.

Alveoli are the primary sites for gas exchange between air and blood.

Normal arterial PaO2 at sea level is roughly 95–100 mmHg.

Most CO2 is converted to bicarbonate by carbonic anhydrase in red blood cells for transport.

Boyle's law: at constant temperature, pressure and volume are inversely related.

Fick's law governs diffusion rate proportional to surface area and concentration gradient.

Tidal volume in adults at rest is about 400–500 mL per breath.

Increases in 2,3-BPG, temperature, and CO2 shift the curve right, facilitating oxygen release.

Forced expiration uses internal intercostals and abdominal muscles to increase intrathoracic pressure.