L5 B cells and Humoral Immunity - Hudig Flashcards
What are the effectors of Humoral immunity>?
abs
HOw is humoral immunity transferred?
Transferred via serum containing Abs or by Abs alone (alone: tetanus toxoid or rattlesnake venom)
How long do cross-species Abs last?
5-7 days
What is the only way to transfer cellular immunity?
by transferring whole cells
Why is it not feasible to transfer cellular immunity?
If not inbred, t cells are rejecte because MHCI and II Ags are mismatches and lead to killing of the transferred cells
T/F: specific Ab concentrations are constant for life
false, they drop
What is the function of an adjuvant?
activates macrophages to produce IL1 and tNF-a
What does the release of TNF-a and IL1 from adjuvant stim’d macrophages cause?
activates helper T and b cells; keeps immunogen localized
An IM vaccine produces what Ig?
IgG
An oral vaccine produces what kind of Ig?
IgA
Is IV a good route for vaccine delivery?
NO
what is the effect of repeated exposure or boosting of an Ag?
incerased quantity and affinity for IgG and IgA
What are the three cases in which high AFFINITY is important?
- Anti-botulin toxin–Ab competition with the cell receptor for the toxin
- Anti-Ebola virus–maximal efficacy
- Tetanus toxoid–multiple boots, small amounts must be effective because of rapid clearance of the toxin
What two Ig’s need high avidity?
IgM and IgA
Define affinity?
binding strength of a single Fab Ag binding site for a single antigenic epitope
define avidity?
Avidity: total combined binding strength of a complete Ig molecule for a complex Ag
Like velcro: each tooth is affinity and the whole strip is avidity
Why is high avidity important for IgA and IgM?
Bacteria and viruses have repeating epitopes in membranes, flagella, and capsules–its where they bind
Which Ig’s have multiple subtypes and what are they?
IgA1-2, IgG1-4
What kinds of secretions have IgA?
Breast milk, gut tears, saliva, vagina
Where do you find IgA?
GI and respiratory tracts
What is the fate of maternal IgA in breast milk?
Maternal IgA from milk remains in baby’s gut, does not significantly enter the baby’s blood circulation
What is the half life of IgA?
6 days
What is the function of IgA?
Neutralization of microbes and toxins at sties of adhesion to the gut wall
how many binding sites do the Ig’s have?
A 4 D 2 E 2 G 2 M 10
Where do you find IgD?
VIRGIN b cells
does iGD have a J chain?
no
what modification does IgD have?
glycosylated
What is the first and second Abs Ig’s made in response to infection?
- IgM
2. IgG
What is the function of IgE
defense against helminths via mast cell degranulation
does igE have a j chainh?
no
what mod does IgE have?
glycosylation
IgG has (high/low) affinity for Abs
high
what is the half life of IgG1/2/4?
21-24 days
what is the halflife of IgG3?
7-8 days
what three Ig subclasses can fix C?
IgM, IgG1, IgG3
Which Ig crosses the placenta?
IgG
Describe the affinity and avidity of IgM
low affinity, high avidity
what is the half life of igM?
5 days
What Ig classes are found in secretions?
IgA and IgM
What are the five means by which IgG antibodies can preotect humans against pathogens?
- Neutralization of microbes and toxins by IgG binding
- Blocks bacterial adhesion in the gut;
- Blocks viral adhesion
- Complement activation
- Ab-dependent cellular cytotoxicity effected by NK cells
Describe the neutralization of microbes by igG binding?
Blocks binding of diphtheria and tetanus toxins–needs high affinity
Give an example of bacterial adhesion in the gut being blocked by aBs?
Salmonella into macrophages, pilin protein in Neisseria
What three big name viruses are blocked from adhering to the GI tract by abs?
poliovirus, rotavirus, enterovirus
What is the result of Ab activated complement?
a. Opsonization and phagocytosis of microbes with Abs by macrophages and neutrophils
what is the most common C protein used by Ab activated C?
C3
C3b, iC3b, C3dg, C3d are (blank) bound via thioester linkage to tag yeast or bacteria
covalently
Are bacteria and yeast likely to be LYSED by the C system?
NO
what is good example of complement causing lysis?
i. Anti-A and anti-B blood group Abs are IgM; good at lysing RBCs
what are the four criteria to activate ADCC? What cell is the effector?
1.Target cell must have membrane Ags
2.Must be IgG1 or IgG3
3.Need high avidity to the Fc receptor
4.CANNOT BE YEAST OR BACTERIA
effected by NK cells
What cells are normally recognized by ADCC?
our cells with virions budding out
what other two cell types do NK cells take care of?
tumor cells and virally infected cell in innate immunity
How can you measure targeted cell death in the lab?
release of radioactive 51Cr; all cells take it up but only lysed cells will release it and you can measure the amount of radiation produced
describe the process of transferring IgA into the gut lumen?
1.IgA moves across basement membranes, binds SECRETORY COMPONENT (poly-Ig receptor) bound to GI epithelial cell basal side
2. Endocytosis
3.Release of IgA dimer + secretory component into lumen
ONLY IN SECRETIONS is secretory component still bound
what other IgM in secretions has secretory component?
IgM
WHere do we find large numbers of mast cells?
lung, gut, and mucosa
(monomeric/multivalent) Ags are needed to trigger mast cells and basophils
MULTIVALENT
Multivalent Ag cross-links to bound Ig(blank)
IgE
Can monomeric Ags trigger degranulation?
NO
Are mast cells only loaded with a single type of IgE?
NO, they can respond to a variety of antigens
What receptor does IgE bind to on mast cells?
FcE receptor
what protein are people with penicillin allergies also allergic to?
egg proteins
What is passive immunity?
○ Rapidly confers immunity even before the individual is able to mount an active response; does not induce long-lived resistance to pathogen.
How the fuck does Rho-gam work?
Prevents RHDneg mom from reacting to RHDpos baby from mixing of blood at birth
Induced Ab feedback inhibition
1. IgG Ab to RHD ag given to mom
2. Ab binds to baby RhDpos RBCs 3. RBC-Ab complex binds to specific B cells IN MOM for RhD epitope
4. Binds Fc-IgG receptor
5. RhD specific B cell signaling is blocked; anti-RhD B cells in mom make no Ab
What triggers fusion of the virus with the cell and entry of viral DNA?
acidificatiion of the endosome
what protein do Abs bind to prevent bacterial adhesion?
adhesins, duh
What happens to toxins once they are endocytosed?
they dissociated from the toxin:receptor complex to free the active toxin chain
what are the two ways to diagnose IgE allergic responses?
intradermal skin prick or IgE serum tests (ImmunoCAP, Immunolite or HY Tec)
What system is used intracellularly in mast cells to cause degranulation?
kinase-phosphorylation system
What two Ig’s do virgin B cells show?
IgM and IgD
HOw many igG’s do you need close together to fix C?
2`
