Biology Chapter 11: Immune System Flashcards
Humoral immunity
refers to the effects of antibodies and B-cells
Cell-mediated immunity
Involved with T-Cells
phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
Antibodies are also called
Immunoglobulins
MHC class I expressed on what type of cells
MHC class I is a protein expressed on the plasma membrane of all nucleated cells (not RBC) that is unique to each individual cell
How would a T-cell respond to a cell expressing MHC class I a) healthy b) virally infected
A) healthy- the cell would display a protein fragment from inside and express it extracellularly- Tcell would not respond
B) Viral - T cells would recognize viral antigens on MHC class I and inject to kill it
Also T cells are likely to recognize new tumour cells
MHC class II expressed on what type of cells?
Immune cells such as macrophages, macrophages-like cells such as dendritic cells and B cells
Describe how MHC class II initiates an immune response
1) MHC II is found on immune cells such as macrophages. If the macrophage consumes a foreign pathogen, some protein fragments will be displayed on the MHC complex of the immune cell
2) helper T cells recognize the MHC II complex and start a large immune response
Epitope
Site on an ANTIGEN that is recognized by an antibody
Characteristics of all white blood cells
- have an immune function
- are nucleated
- made in the bone marrow
Most abundant leukocyte
Neutrophil - make up 60% of all leukocytes
Neutrophil
the most abundant WBC (60% of all WBC).
Main role: phagocytose invading bacteria (first responders to infection)
Lymphocytes are
second most abundant WBC
(30% of WBC)
Includes B-cells, T-cells and Natural Killer Cells
Span BOTH innate and adaptive immune systems
Natural Killer Cells
Considered part of the innate immune system BUT can also help the adaptive immune system because they respond to cells that have been tagged by antibodies and destroy them
respond to cells infected by viruses and tumor cells
monocytes
make up 5% of WBC
role: travel to tissues and differentiate into macrophages and dendritic cells
largest WBC by size
Macrophages
WBC
Differentiated from Monocyte
Role: phagocytes that dispose of cellular debris and non-cellular foreign material
Dendritic Cell
WBC
Differentiated from monocytes
found in cells with contact with external environment
bridge gap between adaptive and innate immune system
interact with external substances to present antigens to T cells
Eonsinophils
3% of WBC
target parasitic infections
Basophils
1% of WBC
Allergic response
release histamine and heparin (anticoagulant- reduces blood clotting) as part of inflammatory response
Mast Cells
simialr to basophils but tend to be located in mucous membranes and connective tissue
Hematopoesis
Production of red and white blood cells
Summarize importance of spleen for the immune system
-has white pulp, rich in lympocytes
-important sites of B cell activation
Summarize importance of thymus for the immune system
Small organ in the chest Where T cells mature
Lympathic System
system of vessels that helps transport fluids and immune cells throughout the body
Lymph
colorless, lipid-rich fluid that flows through lympathic system
Lymph nodes
Pockets of lympathic tissue that house high concentrations of T and B cells
Swell during infection
Function of Lympathic System
1) Maintaining fluid balance
2) Collecting and returning interstitial fluid to circulation
3) Transporting cells and biomolecules within lymph
4) Producing lympocytes
what enzyme does saliva contain to break down pathogens
lyzoyme - breaks down bacterial cell wall
Phagocyte vs macrophages
Phagocyte = any cell that engages in phagocytosis
Ie neutrophils, monocytes, macrophages, dendritic cells and mast cells
So macrophages are a type of phagotype
Complement System
signalling cascade of 30 proteins that tag pathogens for destruction (opsonization)
complement cascade is a part of the innate immune system, but it also interacts with antibodies from the adaptive immune system to enhance immune responses.
Leukocytes induce
inflammation
Cytokines
diverse class of signalling proteins that are involved in coordinating the immune response and inflammation
Interferons
subset of cytokines that are known to have antiviral effects
Adaptive immune system made up of
T cells and B cells (antigen specific)
T Cell Positive Selection
T-cells with appropriate immune response are selected while t-cells that don’t respond to putative antigens are eliminated
T-Cell Negative Selection
T-cells that show too strong of a response are eliminated
What is the T-cell response to a cell presenting an abnormal fragment its MHC I receptor
CD8+ cytotoxic T cells (killer T-cells) kill cells with abnormal MHC class I (virus/tumor)
inject cells with substances that induce apoptosis
Antigen-presenting cells
Dendritic cells
macrophages
B cells
What happens when an antigen-presenting immune cell has a foreign antigen on its MHC II receptor?
CD4+ surface receptor on helper T cells recognize foreign pathogen
helper t cell secretes cytokines to recruit other immune cells to strengthen the response, including innate immune cells like neutrophils, macrophages
how to remember which MHC goes with which CD
numbers multiple to get 8
ie MHC II * 4 = 8
MHC I * 8 = 8
After immune response, CD8 and CD4 T cells
become memory t cells to more quickly respond to infections (ie vaccines)
Role of B cell
learn to recognize antigens and to differentiate into plasma cells which secrete large amounts of antibodies in response
After being produced in the bone marrow, where do B cells go?
To the lymph nodes and spleen
What are b cells called before they’ve seen an antigen
naive b cells
Once a b cell is presented with a matching antigen (such as by an antigen presenting cell like a dendritic cell) what happens
b cell proliferates (conal expansion)
2 fates of activated b cells
1) become plasma cells (short lived cells that produce massive amounts of antibodies in an infection)
2) memory cells (persist for the entire life of the host) - remember the antigen they were activated by
passive immunity.
the transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another.
Antibodies have how many light chains and heavy chains per antibody?
2 light chain and 2 heavy chain
conserved antigen
means that it does not change significantly over time.
These antigens are essential for viral survival, so the virus cannot easily mutate them without damaging itself.
Targeting conserved antigens is effective because the virus cannot escape easily through mutation.
