Innate Immunity Overview

Defensive mechanisms that are active prior to infection and respond rapidly. It plays a crucial role in activating the adaptive immune response.

The adaptive immune response is inducible or tailor-made, involving T and B cells.

The innate immune response has a limited number of conserved germline-encoded receptors.

<p>The adaptive immune response is highly diverse, with a very large number of receptors arising from genetic recombination of receptor genes in each individual.</p> Signup and view all the answers

<p>The innate immune response has some memory in NK cells.</p> Signup and view all the answers

<p>The innate immune response is perfect in its discrimination between self and non-self. There are no microbe-specific self/non-self patterns in the host.</p> Signup and view all the answers

<p>The adaptive immune response is very good at self/non-self discrimination. Occasional failures of discrimination can result in autoimmune disorders.</p> Signup and view all the answers

<p>Antimicrobial peptides, proteins, and mediators are soluble components of the innate immune response in blood.</p> Signup and view all the answers

<p>Antibodies and cytokines are soluble components of the adaptive immune response in blood.</p> Signup and view all the answers

<p>The major cell types of the innate immune response include phagocytes (monocytes, macrophages, neutrophils, NK cells, other leukocytes, epithelial, and endothelial cells), and dendritic cells.</p> Signup and view all the answers

<p>The major cell types of the adaptive immune response include T cells, B cells, and antigen-presenting cells (APCs). B cells can also serve as APCs.</p> Signup and view all the answers

<p>Chemokines are smaller cytokines specialized in directing cell movement, acting like breadcrumbs leading to infection sites.</p> Signup and view all the answers

<p>Cytokines are involved in cell-to-cell communication and are essential for coordinating immune responses.</p> Signup and view all the answers

<p>ILC3 (A), ILC1 (B), Natural Killer Cells (C), ILC2 (D)</p> Signup and view all the answers

<p>ILCs recognize broad patterns and act like T cells until T cells can clonally expand. ILCs can already do much of what differentiated T cells can do to gain an early advantage.</p> Signup and view all the answers

<p>The skin serves as a barrier with several mechanisms: shedding outer layers removes attached organisms, slightly acidic pH (5-6) inhibits growth, high salt concentration is unfavorable, periodic drying discourages growth, and non-specific chemicals like psoriasin are present.</p> Signup and view all the answers

<p>Direct factors like nutrition, physiology, fever, age, and genetics, as well as indirect factors like hygiene, socioeconomic status, and living conditions can impact physical barriers.</p> Signup and view all the answers

<p>Physiological factors like fever are part of the innate immune system and function to slow down bacterial and viral replication. Macrophages release inflammatory cytokines (IL-1, IL-6, and TNF-α) to induce fever, which also makes macrophages more effective at phagocytosis.</p> Signup and view all the answers

<p>For a cell to respond to a cytokine, it must have the receptor that is able to recognize that cytokine. It requires both the cytokine and its corresponding receptor. Different cell types can have different cytokine receptors, allowing for specific responses to different stimuli.</p> Signup and view all the answers

<p>Phagocytosis is the process by which phagocytic cells recognize, ingest, and kill extracellular microbes.</p> Signup and view all the answers

<p>Monocytes, tissue macrophages, dendritic cells, and neutrophils are phagocytic cells.</p> Signup and view all the answers

<p>Phagocytosis helps cellular communication by breaking pathogens into 'breadcrumbs' that attract other phagocytic cells. Some of these 'breadcrumbs' are attached to MHC molecules, which can be presented to T cells.</p> Signup and view all the answers

<p>Phagocytosis occurs through the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Phagocytic cells have receptors that bind to these molecules.</p> Signup and view all the answers

<p>PAMPs are cell wall components, such as mannan, β-glucan, lipopolysaccharide, peptidoglycan, and proteins.</p> Signup and view all the answers

<p>Monocytes are macrophages that are present in the blood. When they travel to tissues, they differentiate into specialized tissue macrophages.</p> Signup and view all the answers

<p>Phagocytosis is crucial for clearing dead cells through the recognition of danger-associated molecular patterns (DAMPs).</p> Signup and view all the answers

<p>DAMPs are danger-associated molecular patterns. Cells undergoing cell death have plasma membrane inversions that expose molecules like annexins, phosphatidylserine, and altered carbohydrates, which are recognized by phagocytic cells.</p> Signup and view all the answers

<p>Phagocytic recognition can occur through opsonin-independent and opsonin-dependent mechanisms.</p> Signup and view all the answers

<p>Opsonins are molecules that bind to microorganisms and dead cells to form a 'tag' that can then be recognized by phagocytic cells.</p> Signup and view all the answers

<p>Examples of opsonins include complement components, mannose-binding lectin, C-reactive protein, and antibodies (produced by B cells).</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Opsonization significantly increases phagocytosis. The more tagging components (opsonins) are present, the higher the likelihood that the target will be recognized, internalized, and destroyed.</p> Signup and view all the answers

<p>Yes, even if there is no innate receptor recognizing a new molecule, the adaptive immune system can tailor a response to it.</p> Signup and view all the answers

<p>MHC class II is crucial for the activation of CD4 T cells, which are important for regulating the immune response.</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Neutrophils are an example of a polymorphonuclear phagocytic cell.</p> Signup and view all the answers

<p>Phagocytic cells utilize bleach and peroxide, which are oxygen-requiring compounds, to destroy microorganisms.</p> Signup and view all the answers

<p>A TLR is a toll-like receptor involved in recognizing pathogen-associated molecular patterns (PAMPs) but not always internalization. TLRs are essential for generating inflammatory responses.</p> Signup and view all the answers

<p>Tissue macrophages, blood monocytes, neutrophils, eosinophils, and dendritic cells all perform endocytosis. Eosinophils are the only cell not included in the phagocytic example.</p> Signup and view all the answers

<p>Lysozyme is an enzyme that hydrolyzes peptidoglycan, a major component of bacterial cell walls.</p> Signup and view all the answers

<p>Lactoferrin/transferrin are important for binding iron, which is an essential nutrient for bacteria.</p> Signup and view all the answers

<p>Calprotectin chelates zinc in Staphylococcus aureus, which is a common bacterial pathogen.</p> Signup and view all the answers

<p>Psoriasin is an antimicrobial peptide produced by human skin and tongue that is effective against Escherichia coli.</p> Signup and view all the answers

<p>Cationic peptides disrupt cell membranes, leading to cell death.</p> Signup and view all the answers

<p>Bacteriocins are peptides produced by normal microbiota, which can be lethal to related bacterial species.</p> Signup and view all the answers

<p>Escherichia coli produces colicins.</p> Signup and view all the answers

<p>Lantibiotics are antimicrobial peptides produced by a variety of Gram-positive genera.</p> Signup and view all the answers

<p>Complement is a series of proteins that act as an opsonin, enhancing the immune response.</p> Signup and view all the answers

<p>Complement includes more than 30 serum proteins.</p> Signup and view all the answers

<p>Complement primarily defends against bacterial infections, bridges innate and adaptive immunity, and disposes of cellular waste.</p> Signup and view all the answers

<p>Complement is named so because it augments (complements) the antibacterial activity of antibodies.</p> Signup and view all the answers

<p>Complement activation begins in different ways, each with specific proteins, but they share the same outcomes. All pathways are activated as a cascade, where the activation of one protein initiates the activation of the next.</p> Signup and view all the answers

<p>Complement activation leads to opsonization (tagging pathogens for destruction), stimulation of inflammatory mediators, and lysis (breaking down) of microbes.</p> Signup and view all the answers

<p>Interferons are classified into three types: type I, type II, and type III.</p> Signup and view all the answers

<p>Interferons induce an antiviral state within cells, making them less susceptible to viral infection.</p> Signup and view all the answers

<p>Many cell types can produce Type I interferons (α, β, and τ), but Type I IFNs are mainly produced by virally infected cells.</p> Signup and view all the answers

<p>IFN II refers to a single interferon, IFNγ.</p> Signup and view all the answers

<p>IFNγ is mainly produced by natural killer (NK) cells and T cells.</p> Signup and view all the answers

<p>The inflammatory response is triggered by foreign substances. It involves capillary expansion (redness), increased vascular permeability (swelling), and leukocyte and plasma protein leakage (edema) to recruit immune cells and fight infection.</p> Signup and view all the answers

<p>CD4 T cells recognize environmental antigens presented on MHC II.</p> Signup and view all the answers

<p>B cells are the primary cellular component of humoral immunity, responsible for producing antibodies.</p> Signup and view all the answers

<p>T cells, particularly CD4 and CD8 T cells, are the key players in cellular immunity.</p> Signup and view all the answers

<p>Natural killer cells and γδ (gamma delta) T cells bridge innate and adaptive immunity.</p> Signup and view all the answers

<p>Granulocytes (basophils, eosinophils, neutrophils), mast cells, NK cells, complement proteins, macrophages, and dendritic cells are all part of the innate immune system.</p> Signup and view all the answers

<p>Basophils, eosinophils, and neutrophils are all categorized as granulocytes.</p> Signup and view all the answers

<p>An antigen is any substance that can elicit an immune response. Similar compounds often trigger the production of distinct and highly specific antibodies.</p> Signup and view all the answers

<p>B cells are the only cells that can make antibodies, which are essential for humoral immunity.</p> Signup and view all the answers

<p>B cells have a B cell receptor (BCR) on their surface, essentially a transmembrane antibody.</p> Signup and view all the answers

<p>B cells can recognize a wider range of antigens, including proteins, carbohydrates, lipids, and nucleic acids. T cells primarily recognize proteins and peptides.</p> Signup and view all the answers

<p>B cells express MHC class II, which presents antigens to CD4 T cells. This is essential for the activation and differentiation of B cells into antibody-producing cells.</p> Signup and view all the answers

<p>CD4 T cells help B cells produce the right isotype of antibodies, tailored to the specific antigen.</p> Signup and view all the answers

<p>The light and heavy chains of a B cell contribute to the recognition of the antigen. They form the antigen-binding site of the antibody, determining the specificity of the antibody.</p> Signup and view all the answers

<p>MHC class I is expressed on virtually every nucleated cell within the body.</p> Signup and view all the answers

<p>MHC class I is involved in the recognition of foreign antigens on infected cells by CD8 T cells.</p> Signup and view all the answers

<p>IL-1, IL-6, and TNF-α are often referred to as the 'inflammatory trio'.</p> Signup and view all the answers

<p>Phagocytosis involves the following steps: 1) Pseudopods engulf bacteria; 2) Bacteria enters the phagosome; 3) Lysosome fuses with the phagosome to create the phagolysosome; 4) Lysosome components degrade bacteria; 5) Degraded bacteria are presented on MHC II to T cells.</p> Signup and view all the answers

<p>Antibodies are secreted as soluble proteins, allowing them to circulate in the blood and lymph to reach target pathogens.</p> Signup and view all the answers