CPR - Immunology {4.03}

What is the primary goal of the lung immune system regarding activation and regulation?

To achieve a balance between protective activation against pathogens and regulation to avoid excessive responses that impair function.

Which specific hair-like structures in the upper respiratory tract provide physical filtration of inhaled particles?

Nasal vibrissae.

The lower respiratory tract is generally considered a _____ environment.

Sterile

What structures hold airway epithelial cells together to prevent pathogen entry into the tissue space?

Tight junctions.

Which two sources in the airway produce mucus to act as a viscous physical barrier?

Goblet cells and submucosal glands.

According to the source material, what mucus-related impairment occurs in patients with cystic fibrosis?

Impaired mucus production.

What is the primary function of ciliated epithelial cells in the innate immune defense?

To perform mucociliary transport to move mucus and trapped microbes up and out of the lung.

Which genetic disorder results in increased susceptibility to pneumonia due to a lack of ciliary function?

Primary ciliary dyskinesia (PCD).

What common chemical exposure is a major cause of acquired lack of ciliary function?

Smoking.

Term: Mucins

Definition: Glycoprotein constituents of mucus that are constitutively produced by Goblet cells.

How do defensins, stored in neutrophils, physically eliminate pathogens?

By forming multimeric pores within the bacterial cell membrane, leading to leakage of contents.

How do surfactants play an immunosuppressive role regarding alveolar macrophages?

They inhibit the phagocytic activity and TLR activation of alveolar macrophages.

Surfactants bind to carbohydrate _____ on pathogen surfaces to facilitate their clearance from the alveoli.

PAMPs

Which pattern recognition receptors (PRRs) do airway epithelial cells use to recognize infections?

Toll-like receptors (TLRs) and Nod-like receptors (NLRs).

A deficiency in which complement component is specifically associated with increased upper respiratory tract infections?

Complement component C3.

What are the three primary outcomes of complement activation in the lung?

Opsonization, direct lysis (via MAC), and proinflammatory effects (via anaphylatoxins).

What is the role of anaphylatoxins such as C3a and C5a in lung immunity?

They activate immune cell recruitment for a proinflammatory effect.

What phenotype do alveolar macrophages typically maintain during homeostasis?

An anti-inflammatory or immunosuppressive phenotype.

Which two anti-inflammatory cytokines are expressed in high concentrations by homeostatic alveolar macrophages?

IL-10 and TGF-β.

Classically activated macrophages (M1) are primarily associated with which type of T helper response?

Th1 type response.

Which cytokine is the primary driver for M1 macrophage activation?

IFN-γ.

Alternatively activated macrophages (M2) are associated with which type of T helper response?

Th2 response.

What is the primary role of M2 macrophages in lung inflammation?

Resolution of inflammation and tissue repair.

Which two cytokines induce the M2 macrophage phenotype?

IL-13 and IL-4.

During homeostasis, lung dendritic cells preferentially drive the differentiation of naive T cells into which subset?

Th2 cells.

In what specific lymphoid tissue does naive B cell activation and class-switching typically occur in the lung?

Bronchial-associated lymphoid tissue (BALT).

Which antibody class is the primary provider of protection in mucosal lung tissue?

IgA.

What receptor is responsible for transporting IgA across the airway epithelium?

Poly-IgA receptor.

In which part of the respiratory tract does secretory IgA (sIgA) play its most important role?

The upper airway.

Which T cell subset is essential for maintaining the lung's immunosuppressive environment to avoid excessive responses?

Regulatory T cells (Tregs).

What is the general effect of a Th1 response on lung tissue?

It is proinflammatory and often leads to tissue destruction.

What is the general effect of a Th2 response regarding the epithelial barrier?

It protects the epithelial barrier and promotes tissue repair.

What is the general effect of a Th17 response on lung tissue architecture?

It is proinflammatory and leads to tissue remodeling.

Why is a Th2 response often preferred in the lung environment?

To protect the epithelial barrier and prevent tissue damage.

Allergies and asthma are classified as which type of hypersensitivity reaction?

Type I hypersensitivity.

Which antibody class mediates the mast cell activation seen in allergic asthma?

IgE.

What receptor does IgE bind to on the surface of mast cells?

Fcϵ receptor (FcϵR).

What immediate event occurs when IgE is crosslinked by an allergen on a mast cell?

Degranulation and release of histamines and other mediators.

How long after allergen exposure does an 'Immediate' Type I hypersensitivity reaction typically manifest?

Within 30 minutes.

What characterizes the 'Late phase reaction' in an asthma attack?

An inflammatory infiltrate rich in neutrophils, eosinophils, and T cells.

Which two Th2 cytokines induce goblet cell hyperplasia leading to mucus over-production in asthma?

IL-4 and IL-13.

Which cytokine is responsible for the generation and activation of eosinophils in the Th2 response?

IL-5.

Which mediators, induced by IL-5 and IL-13, are responsible for recruiting eosinophils to the lung?

Eotaxins.

What is the clinical effect of histamine on the bronchioles during an allergic reaction?

Bronchoconstriction.

Which asthma treatment class works by inhibiting the transcription of proinflammatory genes?

Corticosteroids.

Which asthma treatment class is specifically used to reverse bronchoconstriction by acting as agonists?

β-adrenergic agonists (Bronchodilators).

Against which types of pathogens is the Th17 response primarily directed?

Extracellular bacteria and fungi.

Which cytokine in the Th17 response induces increased epithelial barrier function?

IL-22.

In chronic Th17 responses like COPD, what two enzymes released by neutrophils cause tissue remodeling?

MMP12 and neutrophil elastase.

Term: Emphysema

Definition: A long-term, progressive lung disease caused by tissue remodeling that primarily results in shortness of breath.

What is the primary immunological mediator of mucus hypersecretion in chronic bronchitis associated with Th17 responses?

IL-17 (leading to neutrophil-mediated effects).

Which T cell subset is primarily responsible for clearing viral infections in the lung?

CD8+ T cells (CTLs).

What type of T cell response is typically required for clearing intracellular bacterial infections?

Th1 response.

Which immune cells are the 'first line' recruited to the site of an acute infection to kill pathogens via ROS?

Neutrophils.

What are the three hallmark cells involved in the Th1 mediated clearance of intracellular bacteria?

Neutrophils, macrophages, and CD4+ T cells.

The release of _____ from mast cells is the initial trigger for airway hyperresponsiveness in allergies.

Histamine

What is the immunological consequence of a deficiency in neutrophil quantity (neutropenia)?

Predisposition to lung pathogens due to the loss of the second line of defense.

Which T cell-derived factor is crucial for M1 macrophage-mediated 'enhanced microbial killing'?

IFN-γ.

Which Th2 cytokine is primarily responsible for driving B cells to class-switch to IgE production?

IL-4.

What determines whether an immunologically naive individual develops asthma or a protective response according to the Hygiene Hypothesis?

Environmental factors (e.g., farm living vs. industrialized society) and genetic predisposition.

Which innate cell type residing near blood vessels and nerves is central to the pathogenesis of asthma through IgE binding?

Mast cells.