Exam 4 Flashcards
Cytotoxic T cells express what?
CD8 to recognize MHC 1 proteins on infected cell
How do cytotoxic T cells act?
they kill antigen-bearing target cells direclty
What do T-helper cells express?
CD4 to recognize MHC 2 protein on infected cell
How do T-helper cells act?
they act through cytokines to promote immune reactions
Cytokines signal what?
B-cells
What are the two subclasses of T-helper cells?
T-helper 1
T-helper 2
Which T-helper cell is less specific?
T-helper 1
How do T-helper 1 cells work?
they attract and activate macrophages for non-specific cellular defense
initiate inflammation
How do T-helper 2 cells work?
stimulate B-cells to produce antibodies
very specific
How do natural killer cells work?
they have no memory but recognize any foreign cells and kill the entire cell
Natural killer cells are an effective defense against what cells?
cancer and virus infected cells
What cells make antibodies?
B-cells
Where are antibodies found?
serum, milk, and gastric secretions
How do B-cells work?
antibodies on cell surface interacts with antigens & B-cell uses phagocytosis to ingest pathogen
Antibodies are also known as what?
immunoglobulins
What is the structure of antibodies?
two heavy chains
two light chains
What fragments of antibodies can bind antigens?
Fab fragments (top 2 parts of the Y shaped antibody)
What fragments of antibodies cannot bind antigens?
Fc fragment (bottom stem of the Y shaped antibody)
What is the protease that digests the antibody into its 3 fragments?
papain
What part of the Fab fragment on an antibody actually binds the antigen?
variable region
it varies from antibody to antibody
What are the 5 types of antibodies?
IgG
IgM
IgA
IgE
IgD
Which type of antibody is found in secretions from mucous membranes?
IgA
Which types of antibodies are found in blood?
IgG and IgM
Which type of antibody is found in serum & is involved in parasite immunity & allergies?
IgE
Which type of antibody is found on the surface of B-cells?
IgD
What is the most common antibody?
IgG
Structure of IgG antibody
2 long heavy chains
2 short light chains
heavy and light chains held together by disulfide bonds
Y shaped
Structure of IgM antibody
5 antibody molecules hooked together by J-chains
What is the first antibody to be made in response to bacterial infection?
IgM
Structure of IgA antibody
2 antibody molecules held together by a J-chain
Structure of IgE antibody
have an extra constant region
look like IgG
Structure of IgD
look like IgG
What are opsonins?
a substance that binds to foreign cells & makes them more susceptible to phagocytosis
What is opsonization?
an immune process that uses opsonins to tag foreign pathogens
What is complement activations mode of action?
- antibodies destroy foreign cells by forming holes in the membrane
- phagocytosis
- attract macrophages & neutrophils through chemotaxis
- inflammation
Define inflammation
a nonspecific response to toxins that is mediated by the release of cytokines & chemokines
is localized to the site of infection
What are the consequences of immune responses?
inflammation
septic shock
hypersensitivity
Define septic shock
a severe inflammatory response that spreads through the entire body
often caused by gram negative bacteria
What mediates type 1 (immediate) hypersensitivity?
IgE antibody
What are some immediate hypersensitivity allergens?
pollen
insect venom
certain foods
dust
animal dander
Describe type 1 (immediate) hypersensitivity
reaction occurs minutes after exposure to antigen
Describe type 2 hypersensitivity
IgG antibodies work against LOCAL antigens
Describe type 3 hypersensitivity
IgG antibodies work against CIRCULATING antigens
Describe type 4 (delayed) hypersensitivity
TH1 helper cells produced inflammatory responses that CAUSED tissue damage
symptoms appears hours after secondary exposure to antigens
What are superantigens?
class of ANTIGENS that can activate an excessive amount of T-cells
Describe active immunity
immune response that is stimulated by the presence of an antigen
causes permanent change
Describe natural active immunity
immunity following recovery from a disease
Describe artificial active immunity
induced by injection of antigen-immunization
Describe passive immunity
temporary immunity due to the presence of antibodies made by another person
Describe natural passive immunity
infants receive antibodies from their mother through milk
Describe artificial passive immunity
induced by injections of pre-formed antibodies
What happens during netosis?
neutrophils self destruct & release NET to stop spread of pathogen
What is the inflammasome?
a complex that senses the presence of nucleic acids from pathogens
What allows for the evolutionary progression of cancer?
cancer cells grow too fast, do not die, have independence from the environment, migrate, and have access to nutrient supply
What is metastasis caused by?
uncontrolled cell growth & evasion of apoptosis
What causes uncontrolled proliferation (cell division) generating a malignant cell?
mutation in APC suppressor gene
active Ras protein
loss of p53 suppressor gene
Production of which 2 proteins cause rapid tumor expression?
MYC and RasV12
What are the 3 steps of apoptosis?
- membrane forms irregular buds called blebs
- membrane protrusions form
- cell breaks apart into multiple apoptotic bodies
What apoptotic caspases are initiator caspases that send signals to active executioner caspases when the cell is under stress?
2, 8, 9, 10
Which apoptotic caspases are executioner caspases that degrade cell components?
3, 6, 7
What is pyroptosis?
form of programmed cell death that induces an immune response
When does pyroptosis happen?
in response to microbial infections & heart attacks
What are PDL proteins?
programmed cell death proteins that can bind to PD1 protein on T-cell & trigger apoptosis
