7.5 Immune Flashcards
What causes the immune response to fever? Function?
Pyrogens – secreted by macrophages
Cause hypothalamus to elevate the body’s set temperature (fever)
Moderate fever can be beneficial, as it causes:
The liver and spleen to sequester iron and zinc (needed by microorganisms to grow and divide)
Increase rate of chemical reactions which speeds up tissue repair
How does early inflammation work?
Inflammatory Chemical Release
Vasodilation and Increased Vascular Permeability
Phagocyte Mobilization
What are cytokines? What are associated with inflammation?
Immune signaller
Interleukins
Tumor necrosis factor
What are acute phase proteins?
Inflammatory proteins released by the liver
C-reactive Protein: ** lab test for inflammation
fibrinogen ** causes increased red blood cell sedimentation – lab test for inflammation
What is the difference between acute and chronic inflammation?
Acute Inflammation: rapid response to cell injury
removes agent of injury
enhances healing
terminates quickly
Chronic Inflammation: persistent inflammation
inhibits healing
continued cellular damage and/or organ dysfunction
In general, what are the characteristics of the adaptive immune system?
antigen-specific - requires the production of specific lymphocytes and antibodies against a specific antigen
systemic - not restricted to the initial infection site
has memory -second encounter causes a more rapid and vigorous response
What are B-cells? Which kind of immunity?
Born AND mature in the Bone Marrow
Housed in lymphoid tissues
Recognize free pathogens (bacteria, toxins, viruses)
Involved in Antibody-mediated Immunity
What are T-cells? Which kind of immunity?
Born in Bone Marrow, mature in Thymus
Housed in lymphoid tissues
Recognize infected or cancerous body cells
Involved in Cell-Mediated Immunity
Involved in activating total, combined immune responses
What is an antigen?
are any molecule or partial molecule that can trigger an immune response
How do B/T-cells become immune competent?
To display receptor- have to become immunocompetent= display a unique receptor for a single pathogen
THEN, go to lymphoid tissue where may encounter antigen, only become mature/activated AFTER binding to antigen
Where do lymphocytes originate and mature?
origin: bone marrow, hematopoietic stem cells
maturation: bone marrow (B-cells) or thymus (T-cells)
Why do lymphocytes need to be able to ID “self”?
able to recognize “self” cells and be unresponsive to self-antigens
positive selection: maintain only cells that recognize “self” proteins - MHC
negative selection: remove cells that are reactive to “self” - self-antigen
How do lymphocytes activate? What happens next?
activation: happens when they actually encounter their specific antigen in the body
proliferation & differentiation: once activated, they will increase in number and make other immune cells (ex: memory cells)
How are B-cells activated?
Specific B-Cell with BCR recognizes specific pathogen and makes:
Plasma Cells: produce specific antibodies for that pathogen
2000 antibodies per second
Lifespan 5-7 days
Memory Cells: store memory of antigens to produce antibodies upon later infection, lay dormant until 2nd infection by same pathogen
How do B-cells proliferate and differentiate?
Plasma Cells: produce specific antibodies for that pathogen
2000 antibodies per second
Lifespan 5-7 days
Memory Cells: store memory of antigens to produce antibodies upon later infection, lay dormant until 2nd infection by same pathogen
What are the 5 types of antibodies?
IgM- B-Cell receptor
IgG- Most common, high after a second exposure
IgA- mostly in mucous membrane
IgE- parasitic/allergic; hypersensitivity
IgD- hypersensitivity
How does an antibody-mediated response get rid of a pathogen?
Neutralization: combine with molecules, viruses to physically prevent them from interacting with cells
Agglutination: clump molecules, bacterial cells together, render non-functional
Precipitation: separate them from solution like a chemical precipitate
Tagging for destruction: mark free pathogens, attract other cells to destroy them
What kind of cell makes antibodies?
Plasma cells
What is the primary response in antibody-mediated response?
first exposure to an antigen is slow
several weeks before antibodies reach their peak concentration
In the meantime symptoms can get worse, even death depending on pathogen strength
What is the secondary response in antibody-mediated response?
second or later exposures to antigen, memory cells can respond quickly, powerfully
within a few days
May not even have symptoms upon 2nd and later exposures
What is the difference between active and passive immunity?
Active Immunity occurs when antibodies are made actively by memory cells, present as long as memory cells intact
natural- due to infection with pathogen
artificial – vaccines with attenuated pathogens
Passive Immunity occurs when antibodies are put into the body without memory cells, gone when supply is gone.
natural – breastmilk, IgA
artificial – serum injection
How do T-cells recognize self vs other?
MHC proteins on cell surface signify “Self”
Antigens displayed via “Antigen Presenting Cells”
What are the 3 types of T-cells?
Cytotoxic T-Cells (CD8)
Helper T-Cells (CD4)
Regulatory T-Cells (CD4-25)
What is a dendritic cell? Significance?
Dendritic cells are specialized macrophages that engulf pathogens
Pathogen broken down into antigens in the lysosome, then an MHC II protein is used to display pathogen on cell surface
Dendritic Cell is now an Antigen Presenting Cell (APC)
What are the 2 types of MHC proteins?
MHC-I shows the cell is self; can show that self is infected
MHC-II only on antigen presenting cell= pathogen found and identified
How do cytotoxic T-cells work?
also called CD8 cells, recognize body cells infected by pathogens by binding to MHC I-self-antigen complexes
Cytotoxic T-cells will then destroy infected body cells by lysis, or granzymes that induce apoptosis
What do helper T-cells do?
Look for MHC-II (antigen-presenting cell), then mount immune response, trigger immune system to react to the antigen, in general
** Work with surveillance cells to activate immune response
What do regulatory T-cells do?
also known as CD4-25 inhibit innate and adaptive immune responses to keep the system in check
What is a Type-1 immediate hypersensitivity?
IgE reaction, “allergy”, atopy, can be local or systemic response
CD4 cells respond to allergen presentation, mast cells release histamine, inflammatory mediators
ex: peanut allergy, animal dander allergy
What is a type-II cytotoxic hypersensitivity?
antigens within cell membrane
triggers cell destruction, phagocytosis
ex: drug reaction, transfusion reaction
What is a type III immune complex disorder?
antigen-Ig complex deposits in tissues – antigen may be unknown
organ, joint dysfunction
ex: systemic lupus erythematosus, rheumatoid arthritis
What is a type IV delayed hypersensitivity?
delayed T-cell response to antigen
ex: poison ivy, transplant reactions
