What triggers the classical pathway of the complement cascade?
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C1 reacts with antibodies that have bound an antigen.
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What triggers the classical pathway of the complement cascade?
C1 reacts with antibodies that have bound an antigen.
What happens to the immune reaction upon second exposure to an antigen?
It is much quicker and has a higher antibody yield.
What is the primary mechanism behind vaccines?
The presence of Memory B-Cells from the first immune response.
What is the third line of defense in the immune system?
Humoral and Cellular Immunity.
What activates macrophages, NK cells, T lymphocytes, and cytokines?
Antigens.
What role do macrophages and NK cells play in cellular immunity?
They destroy intracellular pathogens.
What is the function of T cells in cellular immunity?
They induce apoptosis of body cells with viruses, intracellular bacteria, or cancerous traits.
What do cytokines enhance in the immune response?
The inflammatory response and activation of other lymphocytes/macrophages.
What do leukocytes and macrophages secrete when exposed to foreign substances?
Pyrogens.
What is humoral immunity also known as?
Antibody-mediated immunity.
What are cytokines?
Proteins made by cells that affect the behavior of other cells.
What effect do pyrogens have on the body?
They increase the body's thermostat.
How can humoral immunity be transferred from person to person?
Via serum.
How do cytokines act on cells?
By binding with specific cytokine receptors.
What are the benefits of fever in the body?
Increases metabolic rate, kills microbes, and speeds up repair.
What do B cells produce?
Antibodies against soluble antigens.
What are antimicrobial proteins?
Proteins that either attack microbes directly or reduce their reproductive ability.
What triggers the release of cytokines in the immune system?
Activation of Toll-Like Receptors (TLRs).
What type of cells are Natural Killer (NK) cells?
Large, granular, lymphoid-derived cells.
What is the role of antibodies in the immune system?
They neutralize bacteria, toxins, and viruses, marking them for destruction by phagocytes or complement.
What role do interferons (IFNs) play in the immune response?
They protect uninfected cells by stimulating them to synthesize proteins that interfere with viral replication.
What are interleukins?
A group of over 35 cytokines that act on leukocytes and are primarily produced by Helper T-Lymphocytes.
What do Natural Killer cells target?
Malignant cells and cells infected by intracellular pathogens (viruses/bacteria).
How do Natural Killer cells kill their targets?
By latching onto invaders and inducing apoptosis.
What is the role of chemokines?
To induce chemotaxis (migration) in nearby cells.
How do interferons attract immune cells?
They attract macrophages and natural killer (NK) cells to destroy infected cells.
What triggers inflammation?
Physical trauma, intense heat, bad chemicals, or infection.
What are lymphokines?
Cytokines produced by lymphocytes, typically T-cells, that attract other immune cells to an infected site.
What do Natural Killer cells secrete to promote inflammation?
Potent chemicals.
What are complement proteins?
A group of over 30 small pro-enzymes produced by the liver, distributed through blood and tissues.
What do injured cells secrete during inflammation?
Cytokines.
What type of system is the immune system considered to be?
A functional system rather than an anatomical or organ-based system.
What are the three ways cytokines can act on cells?
Autocrine, paracrine, and endocrine manners.
What characteristic do Natural Killer cells use to identify their targets?
They target all cells that lack 'self' surface receptors (non-specific).
What initiates the complement system?
It is stimulated via one of three pathways: Classical, Alternative, and MB-Lectin.
What are the main components of the immune system?
A diverse array of molecules and trillions of immune cells, especially lymphocytes.
Which immune cells are attracted to the injured/infected area during inflammation?
Macrophages, Neutrophils, and Lymphocytes.
What determines the manner in which cytokines act?
Their ability to enter circulation and their half-life in blood.
Where do Natural Killer cells patrol in the body?
In blood and lymph.
What is opsonization in the context of the complement system?
The process where C3b targets foreign particles for phagocytosis.
Where do immune cells and molecules inhabit?
Lymphoid tissues and circulate in body fluids.
What are the characteristic signs of inflammation?
Heat, redness, pain, and swelling.
What is the function of the Membrane Attack Complex in the complement system?
It creates a pore in the plasma membrane of bacteria, leading to lysis of antibody-coated cells.
What is the role of IL-6 in inflammation?
It has pyrogenic action on the hypothalamus, stimulates the acute phase response in the liver, and activates lymphocytes during antigen presentation.
What does the immune system protect the body from?
Infectious microorganisms, cancer cells, transplanted organs, grafts, and other foreign material.
What role does C5a play in the immune response?
It attracts phagocytic cells to the area, facilitating chemotaxis.
What is the role of mucous membranes in the immune system?
They trap bacteria and prevent their entry into the body.
What is the function of TNF-α in the inflammatory response?
It induces local inflammatory response, has pyrogenic action on the hypothalamus, and helps contain infection.
What enzyme found in saliva and tears destroys bacteria?
Lysozyme.
How does the complement system activate the adaptive immune system?
By enhancing the uptake of complement-coated antigens by antigen-presenting cells and the response of B-cells to these antigens.
What can be a maladaptive response during sepsis?
Systemic release of pro-inflammatory cytokines and pro-inflammatory complement, leading to vasodilation and septic shock.
How can the immune system act to protect the body?
Directly by cell attack or indirectly by releasing mobilizing chemicals and antibody molecules.
How does sticky mucus contribute to immunity?
It traps bacteria in the digestive and respiratory tracts.
What are acute phase proteins?
Proteins produced by the liver in response to inflammatory cytokines.
How does the Adaptive Immune System differ in terms of location of response?
It is systemic; immunity isn't restricted to the initial infection site.
What is a pathogen?
A microorganism that is able to cause disease.
What is the function of cilia in the respiratory system?
They sweep bacteria into the mouth to be swallowed.
What characteristic of the Adaptive Immune System allows it to mount stronger attacks on previously encountered pathogens?
It has memory.
What is the role of C-Reactive Protein (CRP) in inflammation?
It acts as an opsonizing agent for microbes and activates the classical pathway of the complement cascade.
What does pathogenicity refer to?
The ability of a microorganism to cause disease.
What is the role of acid secretion in the immune system?
It kills microbes on the skin, vagina, and stomach.
What does Mannose-binding Lectin (MBL) do?
It acts as an opsonizing agent for microbes and activates the lectin pathway in the complement cascade.
What does self-limitation in the Adaptive Immune System refer to?
The immune response wanes off following the elimination of antigens.
What is virulence?
The degree of pathogenicity.
What are macrophages?
Large phagocytic cells derived from bone marrow that engulf and kill microorganisms.
What are granulocytes characterized by?
They possess cytoplasmic granules and are named according to the staining ability of these granules. Eosinophils - Eosin dye. Basophils - Basic dyes
What is self-tolerance in the context of the Adaptive Immune System?
The immune system is non-reactive to self-antigens.
Why is the measurement of acute-phase proteins important?
It serves as a useful marker of inflammation.
How do macrophages respond to invading microorganisms?
They engulf and kill them innately.
What are opportunistic pathogens?
Bacteria that cause disease in a compromised host.
What is the significance of neutrophils in the blood?
They are the most numerous granulocyte, making up 40-75% of blood samples, and are the most important granulocyte.
What role does the Adaptive Immune System play in the inflammatory response?
It tremendously amplifies the inflammatory response.
What do macrophages do with microbes marked by an adaptive immune response?
They engulf and kill them.
What is normal flora?
Harmless bacteria consistently associated with the host.
What is the primary function of neutrophils?
They release toxic chemicals into the extracellular fluid, killing both the target and themselves.
What are the two types of immunity in the Adaptive Immune System?
Humoral immunity and cell-mediated immunity.
What additional roles do macrophages play in the immune response?
They scavenge dead cells, induce inflammation, and present antigens to T-helper cells.
What constitutes an infection?
When an organism breaches a body surface.
What is the life span of neutrophils?
5 days; they do not return to the blood and turn into pus.
What is the primary function of antibodies in humoral immunity?
To neutralize toxins and infectious organisms, can be transferred from one individual to another via serum
What do macrophages secrete to help induce inflammation?
Pro-inflammatory cytokines and chemokines.
What factors determine if an infection leads to disease?
Route of entry, number of pathogens, and immune status of the host.
What roles do eosinophils play in the immune system?
They are involved in anti-parasite and anti-fungal roles, weakly phagocytic, and can kill extracellular organisms by excreting toxic chemicals.
What is the primary function of activated cells in cell-mediated immunity?
To destroy infected or foreign cells, can be transferred from one individual to another via effector cells
What are the three main components of the immune system?
External barrier, innate immune response, and adaptive immune response.
What is the life span of eosinophils in tissues and blood?
12 days in tissues or 30 minutes in blood.
What occurs during the recognition phase of the Adaptive Immune System?
TLRs and PRRs on macrophages and dendritic cells recognize PAMPs on antigens and engulf them via phagocytosis. The antigen is processed and parts are displayed on cell surfaces. Macrophages and damaged epithelia secrete pro-inflammatory cytokines to attract more immune cells
What are basophils associated with?
Hypersensitivity and allergic reactions.
What happens during the activation phase of the Adaptive Immune System?
Activated dendritic cells migrate to lymph nodes, activating naive T-cells, which then activate naive B-cells to secrete antibodies.
What do basophils release that contributes to inflammation?
Histamine, serotonin, and prostaglandins, which increase inflammation and capillary permeability.
What is the effector phase in the Adaptive Immune System?
Active T-cells and secreted antibodies leave the lymph node to fight the infection via the lymph and blood.
What is the role of Antigen-Presenting Cells (APCs) in the immune system?
They engulf and process antigens, then present fragments on their surfaces for recognition by T-Cells.
How do basophils affect phagocyte migration?
They increase phagocyte migration to the site of infection.
What are the important cytokines involved in the Acute Phase Response?
IL-1, IL-6, and TNF-alpha.
What is the role of IL-1, IL-6, and TNF-alpha in the Acute Phase Response?
They are critical for the synthesis of Acute Phase Proteins and mobilizing neutrophils from bone marrow.
Why do T-Cells require Antigen Presentation?
T-Cells are unable to independently recognize antigens.
What effect do IL-1, IL-6, and TNF-alpha have on the hypothalamus?
They have pyrogenic effects.
What is the most efficient type of Antigen-Presenting Cell?
Dendritic Cell.
What are the two main types of immune systems?
Innate and Adaptive immune systems.
What is the function of IL-8?
It is a chemokine that attracts granulocytes, monocytes, and CD8+ T-cells.
What is a characteristic of the Innate immune system?
It is non-specific and responds rapidly.
Which cells secrete IL-8?
Monocytes, macrophages, and injured epithelium.
What is the first line of defense in the Innate immune system?
Surface barriers like skin and epithelia.
How do Dendritic Cells present antigens?
They present antigens bound to MHC-I or MHC-II on their cell surface.
What is the major cytokine activator of macrophages?
IFN-gamma (Interferon-gamma).
What type of cells are involved in the Innate immune system?
Phagocytes and Natural Killer (NK) cells.
What happens after Dendritic Cells activate 'Naive' T-Cells?
The T-Cells leave the lymph nodes and travel to the site of infection.
Which cells produce IFN-gamma?
T-helper cells, T-cytotoxic cells, and NK cells.
What role do Macrophages play in the immune response?
They recognize patterns on foreign organisms and process/present antigens via MHC-II.
What is the role of the Adaptive immune system?
To provide specific responses to pathogens and develop memory.
What type of immunity involves lymphocytes and antibodies?
Adaptive immunity.
What is the specificity of the Innate immune system?
Non-specific; it responds to all foreign substances.
What do TLRs (Toll-like Receptors) on Macrophages recognize?
Patterns (PAMPs) on foreign organisms.
Does the Innate immune system have memory?
No.
What is the least efficient type of Antigen-Presenting Cell?
B-Lymphocytes.
Does the Adaptive immune system have memory?
Yes.
How do B-Lymphocytes recognize specific antigens?
Through their immunoglobulin-based surface receptors.
What is the role of skin in the Innate immune system?
It prevents the entry of pathogens.
What is the process that occurs after B-Lymphocytes ingest an antigen?
They present the antigen via MHC-II to T-Helper Cells, which then activate the B-Cell to differentiate into a Plasma Cell that secretes antibodies.
