Unit 3 Flashcards
Activation of the humoral immune system can cause changes in antibody structure. What are the changes and what is the purpose of them?
affinity maturation and heavy chain can change structure (isotype switching). Purpose is to produce higher affinity antibodies
What are the 4 ways antibodies help fight infections?
neutralization, opsonization, antibody-dependent cellular toxicity, and complement activation
What is neutralization?
blocks viral binding sites so viruses longer interact and infect other cells
How does opsonization work?
all phagocytes have many different types of receptors allowing them to recognize, bind, and phagocytose microbes
What is antibody-dependent cellular cytotoxicity (ADCC)?
Fc gamma receptor binds to constant region of IgG. IgG antibodies stuck on surface. NK cells has gamma receptors that bind to IgG antibodies and kills the IgG
What is phagocytosis and how is it involved in complement activation?
What is inflammation and how is it involved in complement activation?
What is microbe lysis and how is it involved in complement activation?
What is the classical pathway and how is it involved in complement??
starts with antibodies bound to an antigen
What is the alternative pathway and how is it involved in complement?
random separation of c3a and c3b. C3b sticks to microbial surface and get same pathway as classical
What is the lectin pathway and how is it involved in complement?
mannose-binding lectin binds to mannose (PAMP). Sticks to surface of microbes and activates complement pathway
What happens if we recognize self-antibodies?
causes autoimmune disease
How can we take advantage of ADCC for therapeutic approaches?
antibodies can be used to target and kill cancer cells
NK cells have what kinds of receptors
gamma receptors
How are NK cells different from CD8 T cells?
NK cells are innate and do not have a T cell receptor and instead bind to constant region of IgG antibodies and kills infected cells.
antibodies are good for what three purposes?
blocking microbes from getting through epithelial barrier, block binding of toxin to cellular receptors, and prevent infection of cells
What is the main function of antibodies?
coat proteins to make it easier for phagocytes to eat up
What are the two main differences between innate and adaptive immunity?
- Innate: Nonspecific, responds quickly
- Adaptive: Specific, responds slowly the 1st time
What are the three ways complement activation is activated?
increases phagocytosis, recruitment of other cells, and osmotic lysis
What are the three ways of regulation of complement activation?
C3a and C3b, C5a and C5b, and membrane attack complex
What may happen if complement is dysregulated?
excessive inflammation
What pathway of complement requires antibody for activation?
classical pathway
What results in the activation of the classical pathway of complement?
antibody bound to antigen
What parts of complement are responsible for inflammation (recruiting immune cells to the site of infection)?
C3a and C5a
Is complement part of the innate or the adaptive humoral immune response?
innate
Complement activation results in inflammation, lysis of microbes and __________?
increased phagocytosis
What is the purpose of opsonization?
to make pathogens easier for phagocytes to recognize, bind and internalize
What cell type is responsible for antibody-dependent cellular cytotoxicity (ADCC)?
Natural Killer cells (NK)
How do phagocytes recognize antibody on microbes?
FcGamma receptors
Check yes or no for each of the following boxes from A to D (check - yes, x - no)
How (and why) do immune responses differ depending on the tissue involved?
How (and why) do immune responses differ depending on the tissue involved?
Mast cells play what role in mucosal immunity?
Macrophages and DCs play what role in mucosal immunity?
B cells (IgA secreting plasma cells) play what role in mucosal immunity?
What types of T cells are involved in mucosal immunity?
CD8 that live in epithelial barrier that can respond to virally infected cells and in the LP/PP, there are CD4 effector, memory, and regulatory T cells
What are the two main types of CD4 effector T cells that are involved and what role do they play in mucosal immunity?
Th17 cells which help to main epithelial barrier function and Th2 cells which enhance fluid and vomit out any parasites
What is the difference between innate and adaptive molecules?
How is mucosal immunity regulated?
TLRs and NLRs of intestinal epithelial cells detect PAMPs and allow commensal bacteria to not be stimulating the response. Regulatory T cells abundant in epithelial tissues control and dampen inflammatory response.
Why do we have regional immunity?
some areas are more vital to our survival than others
What is the general anatomical organization of epithelial barriers?
How does a regional immune system differ from the whole immune system?
Where are epithelial barriers found?
What are the three immunological properties of the GI tract?
mucus layer, antibiotic peptides, and secretory IgA
What is the structure of the gastrointestinal system?
How does the gut prevent infections?
Epithelial cells are joined by what?
tight junctions
Epithelial cells are joined by what?
tight junctions
What are the six chemical barriers to pathogens?
Fatty acids in skin, low pH, pulmonary surfactant, enzymes in tears and saliva, defensins, and normal microbiota
What is the function of defensins?
Prevent establishment of bacteria
What is the function of defensins?
Prevent establishment of bacteria
Secretory IgA is a _____?
dimer
How is IgA secreted?
After affinity maturation and isotype switching, constant region of IgA binds to Poly-Ig receptor. Poly-Ig receptor chaperones IgA molecule across epithelial barrier where it’s released into the lumen
What is the role of Peyer’s Patches in adaptive immunity?
provide a mini lymph node where B and T cells interact within the tissues. B cells are activated from IgM to IgA without T cell help
Commensal microbiome are necessary for what?
proper immune development
Commensal microbiome are required for what?
innate immune responses in the gut
Commensal microbiome influence _____ and ________ adaptive immune responses
local; systemic
How does the immune system balance immune defense against intestinal pathogens vs. tolerance to food and commensals?
Treg cells
What is the dominant secreted immunoglobulin in reproductive tract immunity?
IgG
Reproductive tract immunity is regulated by what?
sex hormones
What is immune privilege?
What four sites are immune privileged and why?
brain, eyes (visually oriented), spinal cord, and sex organs (pregnant uterus and testicles)
How is immune privilege maintained?
What happens if immune privilege is broken?
What are the benefits/risks of this immune privilege?
What three consistent strategies for immune tolerance?
physical barrier, Tregs, and regulatory cytokines
What are the three structural features of the eye in ocular immune privilege?
Retinal pigment epithelium, reduced MHC expression, and avascular and alymphatic cornea
What are the two reasons testicles need to be immune privileged?
limit inflammation that may impair male fertility and many self antigens in adult testis are first expressed at puberty
How does testicular immune privilege work?
- blood-tissue barrier to keep out immune cells
- hormones (androgens) –> low inflammation via macrophages
- Local regulatory cytokine production
What is the function of complement regulatory proteins?
to ensure complement cannot activate in specific localized areas
CTLA4 is a regulatory protein that binds to
B7
What prevents naive cells from becoming inflammatory T cells and activation of neighboring T cells?
IDO
What macrophages develop in the brain?
microglia
What are the consequences of losing immune privilege?
inflammation in immune privileged sites
What is sympathetic ophthalmia?
trauma hits the eye releasing some self antigens causing antibody production and blindness to both eyes
What is a situation when immune privilege is detrimental to health?
viral encephalitis
What is the tumor micro-enviornment (TME)?
tumor-associated macrophages produce regulatory cytokines inhibiting activation of NK cells and T cells to keep the immune system from responding to those macrophages
What is the metabolic pathway that leads to regulation of immune cells in pregnancy and cancer?
tryptophan
What are the tolerance-inducing receptors?
Fas-FasL, TRAIL-TRAILr, and PDL/PDL1
What are the basic mechanics of the immune response to SARS-CoV2?
virus particles infect mucosal epithelial cells via ACE 2 receptor. Innate response is activated through DAMPs and PAMPs released by infected cells. Innate response releases cytokines and leads to the adaptive immune response
What are the 3 main ways immune mechanisms interact with the CNS?
coagulopathies and thrombus formation, direct viral invasion of neurons and cerebrovascular endothelial cells, and overproduction of cytokines
What are the CNS related outcomes of the immune response to SARS-CoV2?
viral replication causing neuron injury, higher BBB permeability, increase in adhesion molecules, and decrease in tight junction proteins
What are some examples of recent treatment approaches?
Type I IFN is a key _______ response
antiviral
What is a cytokine storm?
overproduction of inflammatory cytokines
What is the adaptive response to SARS-CoV-2?
WBC with viral antigen displayed on surface. Antigen presented to helper T cells activating cytotoxic T cells and B cells to produce antibodies