Chapter 15+16: Innate Immune Response

What is the difference between nonspecific and specific immune responses?

Nonspecific immune responses are innate, meaning every response is the same, has no memory, and cannot differentiate between types of invasions. Specific immune responses are adaptive, meaning every response is unique and the second exposure to a pathogen results in a much faster response due to memory from previous encounters.

What does it mean that the nonspecific immune response has no memory?

It means that the immune system treats every pathogen the same, regardless of past encounters.

How does the specific immune response improve upon subsequent exposures to pathogens?

The specific immune response improves because it remembers the pathogen from previous encounters, leading to a faster and more effective response

What are the mechanical barriers of the innate immune response?

Mechanical barriers include skin and mucous membranes, tears, coughing, sneezing, and acidic secretions from the skin which destroy pathogens.

What is the overall function of the innate immune response?

The overall function is to prevent the entrance of pathogens into the body.

What happens when the skin is breached?

The mechanical barriers can be breached when the skin is broken, allowing pathogens to enter the body.

What role do neutrophils play in the innate immune response?

Neutrophils are phagocytes that are usually the first white blood cells (WBCs) to arrive at an infection, and they die after a single use, forming pus that contains dead neutrophils and pathogens.

How do macrophages function in the immune response?

Macrophages, which derive from monocytes in the blood, leave the blood and increase in number at the infection site, acting as clean-up cells and including various types like dendritic cells and microglia.

What is the function of basophils in the immune response?

Basophils are mobile cells that release chemotactic factors to attract more white blood cells to the site of infection.

What is the role of mast cells in the immune response?

Mast cells are nonmobile and found near potential pathogen influx sites, releasing chemotactic factors and can also phagocytose bacteria.

What do eosinophils do in the immune response?

Eosinophils act as moderators of the inflammatory response and kill parasites by releasing enzymes.

What types of cells are lymphocytes and what is their significance?

Lymphocytes include B cells and T cells; they play crucial roles in adaptive immunity. Natural Killer Cells (NKC) recognize and

What are the functions of antimicrobial proteins?

Antimicrobial proteins prevent entry into cells, cause vasodilation, increase permeability, attract white blood cells (WBCs), and enhance phagocytosis.

What is the role of interferon in the immune system?

Interferon protects the body against viral attacks by stimulating neighboring cells to produce antiviral proteins.

What is complement and its significance?

Complement is a group of about 20 proteins that circulate in the plasma in an inactive state. When activated, they bind to bacterial cells and cause them to lyse, functioning in both innate and adaptive immune responses.

What are Toll Like Receptors (TLRs)?

Toll Like Receptors (TLRs) are integral proteins found on the cell membrane of phagocytes that trigger immune responses to various bacterial and viral pathogens.

How do TLRs contribute to the immune response?

There are 10 different TLRs on human phagocytes that bind to Pathogen Associated Molecular Patterns (PAMPs), triggering infected cells to undergo apoptosis, initiate the inflammatory mechanism, or stimulate the adaptive immune response.

What are the three main functions of the inflammatory response?

1. Prevents the spread of damaging agents to nearby tissues. 2. Disposes of cell debris and pathogens. 3. Sets the stage for the repair process.

What are the cardinal signs of inflammation?

The cardinal signs of inflammation are redness, heat, swelling, and pain.

What two factors cause edema in the injured area during inflammation?

Vasodilation and increased vascular permeability allow protein-rich fluid to seep into the injury site, causing edema.

What is leukocytosis in the context of inflammation?

Leukocytosis is the increase in white blood cells (WBCs) in the blood as part of the inflammatory response.

What are chemotactic factors and their role in inflammation?

Chemotactic factors are released by injured cells to attract phagocytes to the infected area.

What triggers the systemic response known as fever?

Fever, or pyrexia, is triggered by the release of pyrogens such as IL-1 from macrophages and neutrophils exposed to foreign substances.

How does prostaglandin E (PGE) affect body temperature?

Prostaglandin E (PGE) raises the set point for the body's internal temperature, leading to fever.

What effects does fever have on the immune response?

Fever can promote interferon activity, elevate the metabolic rate to enhance healing, and inhibit the reproduction of pathogens.

What are the three key characteristics of the adaptive immune response?

1. It is antigen-specific. 2. It is systemic. 3. It has memory.

What are the two major components of the adaptive immune response?

1. Humoral (antibody-mediated response) involving B cells. 2. Cell-mediated immunity involving T cells.

How are lymphocytes produced?

Lymphocytes are produced from lymphoblast precursors in red bone marrow.

Where do B cells mature?

B cells reach maturity in the bone marrow before being released into the bloodstream.

Where do immature T cells migrate for maturation?

Immature T cells migrate to the thymus to mature

What is an antigen?

An antigen (Ag, Antigen generating) is any molecule that triggers an immune response, usually with a fairly high molecular weight, and complex molecules unique to individuals, such as proteins, polysaccharides, glycoproteins, and glycolipids.

What types of antigens does the body typically attack?

The body usually only attacks 'non-self' antigens.

What is the difference between complete and incomplete antigens?

Complete antigens are both immunogenic and reactive (e.g., viruses, bacteria, fungi), while incomplete antigens, or haptens, are reactive but not immunogenic unless they bind to other proteins in the body.

What are haptens?

Haptens are incomplete antigens that can cause a reaction only when bound to other proteins in the body, such as pet dander, poison ivy, cosmetics, and perfumes.

Where do immature T cells migrate for maturation?

Thymus

What are antigenic determinants (epitopes)?

Antigenic determinants, or epitopes, are regions on the surface of an antigen that are immunogenic. Simple antigens may only have one or two epitopes, while more complex antigens may have hundreds that bind and activate different types of antibodies.

What are self antigens and how are they displayed?

Self antigens are displayed by all body cells, usually by MHC I complexes.

What is the role of MHC I and MHC II complexes in antigen recognition?

MHC I complexes are found in nucleated cells and raise a red flag if they display a foreign antigen, while MHC II complexes are found in macrophages, B cells, and monocytes, causing costimulation to occur when processed antigens are present.

How do invading pathogens differ from host cells in terms of antigenic determinants?

Invading pathogens have antigenic determinants on their surfaces that are different from those of the host.

What is required for lymphocytes to become immunocompetent and self-tolerant?

All lymphocytes must undergo education.

Where are T-cells created, and where do they mature?

T-cells are created in red bone marrow but mature in the thymus gland, where they undergo positive and negative selection.

What is the difference between positive and negative selection in T-cell maturation?

Negative selection culls T-cells that do not react to foreign antigens or react to self-antigens. Positive selection retains T-cells that react to foreign antigens but not to self-antigens.

Where do B-cells mature and how do they compare to T-cells?

B-cells mature in the bone marrow and undergo a similar selection process as T-cells, eventually colonizing similar tissues.

What are Antigen Presenting Cells (APCs) and their role?

APCs help T-cells detect antigens by engulfing them and presenting fragments attached to MHC complexes. Cells that act as APCs include dendritic cells, macrophages, and activated B

What happens to naïve B-cells when they encounter an antigen?

Naïve B-cells have receptors for an antigen on their surface. When challenged by the antigen, they activate specific receptors, beginning to divide.

What is clonal selection in B-cells?

Clonal selection rapidly creates plasma cells and memory cells in response to the antigen.

What do plasma cells do after they are formed?

Plasma cells secrete antibodies at rates up to 2000 per second for about 4-7 days.

What is the role of memory cells in antibody-mediated immunity?

Memory cells are long-lived and retain the imprint of the antigen, allowing them to respond almost immediately to future attacks.

What is the duration and characteristic of the primary response in antibody-mediated immunity?

The primary response occurs after first exposure to an antigen and takes about 3-7 days to form antibodies, usually making the individual feel sick, with antibody production peaking about 10 days later.

What characterizes the secondary response to an antigen?

The secondary response occurs upon re-exposure to the same antigen or a similar form, where B memory cells recognize it, resulting in a faster and greater magnitude response that is often not felt.

What do B cells produce in response to invasion?

B cells produce antibodies, which are specialized globulins known as immunoglobulins (Ig).

What are the two types of regions in an antibody's structure?

Antibodies have variable regions (heavy and light chains) that bind to antigens and constant regions that can bind and activate complement.

What are the five general classes of antibodies?

The five classes of antibodies are IgG, IgM, IgA, IgE, and IgD.

What is the function of IgM in the immune response?

IgM often fixes complement, is usually the first antibody produced, and is a strong agglutinating agent.

How does IgA function in the immune system?

IgA is secreted into tears and mucous, protecting body surfaces, and is also found in colostrum.

What is the role of IgG antibodies?

IgG is the most abundant antibody in plasma, activates complement, is the main antibody in primary and secondary responses, and can cross the placenta.

What effects do antibodies have on antigens?

Antibodies can neutralize antigens, agglutinate them, precipitate small soluble ant

What is the neutralization effect of antibodies?

Antibodies can bind directly to the antigenic determinant and interfere with or deactivate the antigen.

What is the agglutination effect of antibodies?

Antibodies can combine with the antigenic determinants on two antigens, rendering them ineffective and making them more susceptible to phagocytosis.

What does precipitation refer to in the context of antibody action?

Precipitation is when small water-soluble antigens settle out of solution and are then engulfed.

How do antibodies activate the complement system?

Antibodies can activate the complement cascade and release factors that induce inflammatory responses and cell lysis.

Where do immature T cells migrate for maturation?

Immature T cells migrate to the thymus gland for maturation.

What are T-cells most effective against?

T-cells are most effective against intracellular microorganisms such as viruses, fungi, bacteria, and parasites.

How are T-cells activated?

Activation of T-cells is regulated by antigen-presenting cells and helper T-cells.

What are the major types of T-cells?

The major types of T-cells are Cytotoxic (CD8), Helper (CD4), and Memory T cells.

What is the function of Cytotoxic T-cells?

Cytotoxic T-cells, also known as Killer or CD8 T-cells, directly kill infected host cells.

What role do Helper T-cells (CD4) play in immune response?

Helper T-cells activate CD8 T-cells and stimulate antibody mechanisms.

What do Memory T-cells do?

Memory T-cells remember pathogens and provide faster responses upon re-exposure.

What is the role of MHC I in T-cell activation?

MHC I is found on nucleated cells and raises a red flag when displaying a foreign antigen.

What is the role of MHC II in T-cell activation?

MHC II is found in antigen-presenting cells and its interaction leads to costimulation of T-cells.

What is costimulation in T-cell activation?

Costimulation occurs when the MHC II complex of an APC binds with a helper T-cell, stimulating cytokine release.

What are the two possible outcomes of helper T-cell activation through costimulation?

Helper T-cells can either proliferate and produce more helper T-cells or stimulate B or T cells.

What effects do Cytotoxic T-cells have on infected cells?

Cytotoxic T-cells cause cells to lyse (contact killing) by releasing perforins and attract other immune cells through cytokines, initiating an inflammatory response.

How are Cytotoxic T-cells produced?

The production of Cytotoxic T-cells is regulated by helper T-cells and antigen-presenting cells. Once activated, they proliferate to produce more Killer T-cells and memory T-cells.

What are Memory T-cells and their activation requirements?

Memory T-cells are long-lived cells that require less activation to respond compared to other APCs.

What is the primary response in T-cell activation?

The primary response occurs after the first exposure to an antigen, leading to the creation of Killer T-cells and memory cells, usually taking about 3-7 days.

What distinguishes the secondary response from the primary response?

The secondary response occurs upon repeated exposure to the same or similar antigen, where memory cells recognize it, resulting in a faster and stronger response.

What is active immunity?

Active immunity is when individuals produce their own antibodies in response to exposure to antigens.

How is passive immunity different from active immunity?

Passive immunity involves the injection of antibodies from another source, rather than the individual's immune system producing them.

What is Active Natural immunity?

Active Natural immunity occurs when an individual is exposed to an antigen naturally and develops antibodies and memory cells.

What is Active Artificial immunity and how is it achieved?

Active Artificial immunity is achieved through vaccination, where an altered form of an antigen is introduced, leading to the formation of memory cells without causing disease.

What is Passive Natural immunity?

Passive Natural immunity is when antibodies are passed from mother to fetus/newborn through the placenta or breast milk, such as IgA.

What is Passive Artificial immunity?

Passive Artificial immunity occurs when antibodies from another source are given through vaccination, providing immediate but temporary