Chapter 1 Overview Of Immune System Flashcards
What is immunology
It is the study of how the body distinguishes between self and non-self, and how it protects our body from foreign invaders
Define immunity
All the mechanisms used by the body as protection from agents foreign to body
Describe innate immunity
Genetically determined and doesn’t require prior exposure or memory. Non-specific and present at birth
Describe adaptive immunity
Gained after birth, produced by the host or donor, specific protection against specific antigens
What are the first 2 lines of immune defense?
Innate and immediate. Both are non-specific. Innate defense involves anatomical and biochemical barriers whilst immediate defense is the inflammatory response
What are some anatomical barriers in the innate immune system?
Skin, keratin, tracheal cilia
What are some biochemical barriers in innate immune system?
Sebaceous glands, mucous membrane, lysozymes, gastric juices, pH, salt concentrations, fever, cytokines, interferons
What is the body’s 3rd line of defense? Describe it
Adaptive immunity. It’s slow and provides specific protection (days and weeks). Takes longer to react than innate system
How long does priming take?
1-2 weeks
What is priming?
Priming is the process of the body learning, assessing, and adapting to foreign antigen. Part of adaptive defense
Describe what complement protein is and does
It’s an opsonin, or binding enhancer, that helps to make phagocytosis easier by neutralizing the negative charge on antigens since immune cells also have negatively charged proteins
What does lactoferrin do and why is it important?
It is a compound that binds iron and removes it from being a bacterial nutrient source
What does alpha-anti trypsin do and why is it important? Which enzyme does it control?
This compound inhibits bacterial enzymes, such as proteases, from breaking down and damaging the lungs. It especially controls the activity of NEUTROPHIL ELASTASE, which normally functions to break down foreign proteins but it can break down alveolar components of allowed to be active for too long
Name the 2 most common binding enhancers AKA opsonins
Antibodies and complement proteins
Name types of phagocytes
Neutrophils, macrophages, dendritic cells
Which type of phagocyte is the most abundant ? What do they typically scavenge for? How long do they last?
Neutrophils. They mostly look for bacteria. Die fighting so don’t last long
Describe natural killer cells. Which progenitor cell generates them?
They come from lymphoid progenitor cells and DO NOT phagocytose! NOT phagocytosis-capable! They instead attack cells that lack the self-surface receptor (likely MHC class molecules?) and induce apoptosis in cancer cells because they lost the self-surface receptor. They contain granules full of chemicals that enhance inflammatory response or are toxic to pathogen
Describe the inflammatory response. What causes it? How does it manifest? What is its function? Which immune defense system does it alert?
Caused by damage to body tissue. There are 4 main manifestations: 1) heat, 2) redness, 3) swelling, and 4) pain. The swelling is due to fluid buildup in tissues (edema). It functions to prevent the spread of damaging agents so it disposes of cell debris and pathogens. Alerts adaptive immune system. Vasodilation.
List the 4 stages of phagocyte mobilization (innate to internal defenses)
1) Leukocytosis
2) Margination
3) Diapedesis
4) Positive chemotaxis
What is leukocytosis?
Excess white blood cell count. In phagocytic mobilization, neutrophils leave the bone marrow and enter the bloodstream
Describe margination. Which surface proteins allow for this process to occur?
It’s when phagocytes, such as neutrophils, cling to the capillary well. CAMs (cell adhesion molecules) are surface proteins that allow them to stick.
Describe diapedesis
This is when phagocytes, such as neutrophils, flatten and squeeze out of capillaries to arrive to site of tissue damage/foreign pathogen
Describe chemotaxis
This is when chemical concentration leads to cell or organism to either go toward or away the chemical stimulus. In the case of phagocytic mobilization, neutrophils demonstrate positive chemotaxis, so they go toward the chemical trail left by inflammatory response
Describe some proteins involved in inflammatory response
Antimicrobial proteins such as interferons (IFNs) and complement proteins. They directly attack microbes and hinder their ability to reproduce. Interferons are named for their ability to “interfere” with viral replication
Describe the complement system. Is it innate or adaptive? How is it controlled?
It is innate. It contains a collection of proteins (C1-C9, factors B, D, and P, and regulatory proteins). It’s a major mechanism of destroying foreign invaders. Body controls it through “complementation activation inhibitors”. It unleashes inflammatory chemicals that amplify ALL aspects of inflammatory response. Enhances both innate and adaptive defenses. Kills bacteria by cell lysis
What activates the complement system? End result?
Reaction between antigen and antibody. End result is lysis of target (bacteria) or enhanced phagocytosis by neutrophils
What is fever useful for? Is it local or system?
It’s useful to increase metabolic rate, thus leads to faster tissue repair. It’s a systemic response.
What does the adaptive response amplify and activate?
Amplifies inflammatory response and activates complement system
Describe 3 traits of adaptive defenses
1) Specific
2) Systemic (not restricted to initial site)
3) Memory (through priming)
What are the 3 types of cells in adaptive immune system?
1) B lymphocytes
2) T lymphocytes
3) Antigen presenting cells (don’t respond to specific antigens)
Is neutralization by antibodies temporary or permanent? What does this signal?
Temporary. Signals for destruction by phagocytes or complement
What are the two ways that T cells (cellular immune response) act against target cells?
Direct killing or indirect killing by the release of chemicals (cytokines) that enhance inflammatory response, or activate other lymphocytes or macrophages
What are the targets of B and T lymphocytes?
B cell = extra cellular antigens
T cell = cellular level. Direct!
Difference between immunogen and antigen?
Immunogens generate immune response. All immunogens are antigens.
Antigens may or may not generate immune response. Not all are immunogens
What is a pathogen?
Any substance that causes disease
Most antigens are ______?
Proteins. But can be nuclei acids, lipids, or polysaccharides
Describe antigens?
Can mobilize adaptive immune response and are large, complex molecules not found in the body normally
Describe functional properties of complete antigens
They have immunogenicity, meaning that they can stimulate the proliferation of specific lymphocytes. They also have reactivity, meaning that they can react with activated lymphocytes and secreted antibodies
What size molecule is recognized as complete antigen?
Greater than 6000 Daltons
What is a hapten? Is it immunogenic on its own?
Incomplete antigen. Typically small molecules that are NOT immunogenic on their own but can be if attached to carrier proteins
Examples of haptens
Pollen, penicillin, poison ivy, animal dander, detergents, cosmetics, and aspirin
Size of haptens?
Less than 1000 Daltons
What are antigenic determinants?
They are epitopes, or part of antigen that antibodies and lymphocyte receptors bind like enzyme binds substrate. They are immunogenic. Only some parts of antigen are immunogenic, and those are the antigenic determinants
Examples of self-antigens?
MHC (major histocompatibility complex) glycoproteins. They are unique to the individual and twins are not 100% identical for these genes
Are self-antigens antigenic?
Not to self but they can be in transfusions or grafts
Function of MHC I and II glycoproteins?
Signposts that display fragmented pieces of antigen on host cell (antigen presenting cell) surface
Where do B cells and T cells mature/get educated/proliferate?
B cells mature in the bone marrow
T cells mature in the thymus
Traits of mature lymphocytes?
Immunocompetent = recognize/bind to ONE specific antigen
Self-tolerant = unresponsive to self/auto-antigens
List the stages of lymphocyte development
- Origin in bone marrow
- Maturation (develop immunocompetence and self-tolerance)
- Seeding secondary lymphoid organs and circulation
- Antigen encounter and activation
- Proliferation and differentiation (differentiate into effector and memory cells)