Immunology DSA Flashcards by Arnold Delpilar

What is the Estimated Osmolarity Equation?

Osmolarity Equation= 2* [Na] + Glucose/18 + BUN/2.8

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What are the 7 solutes and what are their intracellular and extracellular concentrations?

Sodium 14/140
Potassium .  120/4
Chloride .   10/105
Calcium .   0.0001/2.5
Bicarbonate .   10/24
Proteins .   -/7
Osmolarity .    290/290

Some
People
Can
Come
But
Penises
Only

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What is the definition of an antigen?

A molecule that is recognized by the immune system and is associated with the adaptive response.

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What is the definition of an immunogen?

An antigen that evokes a specific immune response.

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What is the definition of a tolerogen?

An antigen that induces immunologic tolerance.

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What is the definition of a pathogen.

An organism that causes disease.

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What is the difference between endogenous and exogenous types of antigens?

Endogenous is the body’s own cellular components or intracellular pathogens.

Exogenous is antigens that can enter the body and freely circulate and are trapped by APCs by phagocytosis.

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What are the 3 subcategories of endogenous antigens.

Autoantigens- self antigens

Alloantigens- tissue specific antigens Ex. HLA, ABO

Intracellular Pathogens- viruses, intracellular bacteria and parasites

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What is an epitope?

Part of the antigen that comes into contact with the Ag-binding site of an Ab

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What are T-dependent Ags?

An antigen that requires both helper T cells and B cells to stimulate an Ab response

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What are T-independent Ags?

Non-protein antigens like polysaccharides and lipids that can stimulate an Ab response without the use of helper T cells.

Usually these have multiple identical epitopes that can cross-link BCRs (B-cell receptors)

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TCRs recognize the _____ sequence of amino acids in proteins (____ ______)

Primary

Linear Epitopes

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What kind of peptides are not recognized by TCRs?

Free peptides

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What are the 2 types of T cell receptors? Which one is dominantly found in the body?

Alpha-Beta TCRs (dominant)

Gamma-Delta TCRs

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What kind of antigens do Gamma-Delta TCRs recognize?

Are they restricted to MHC/HLA?

Recognition of lipid antigens

Also recognize DAMPs

No, they are not restricted to HLA/MHC

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What is the definition of a hapten?

Small molecules that cannot induce an immune reponse alone, therefore they cannot activate T-cells

Univalent so they cannot activate B cells

What are haptens used for?

Drug allergies

Making Vaccines

What do Superantigens bind to on the TCR? What do they cause the release of?

Bind directly to HLA class II molecules and the variable beta portion of the TCR.

Stimulate the release of cytokines by activating T cells

What is the structure of an Antibody?

4 Polypeptide chains:

2 Heavy chains- Variable (Fab), Constant (Fc)
2 Light chains- Variable (Fab), Constant (Fc)

Which part of the antibody chains have biological activity and which binds to the antigen?

Constant (Fc) region has biological activity, meaning it elicits a reaction within the cell

Variable (Fab) region binds to the antigen

What 2 molecules are used to digest antibodies?

What does each digest the antibody into?

Papain- 2 Fabs, 1 Fc

Pepsin- F(ab’)_2

*Note that Pepsin retains single bivalent Ag binding capability

What is the definition of an idiotype?

Antigenic determinants on the variable regions.

When do we see high amounts of IgMs? What is unique about their structure?

IgMs are the first antibody produced in a PRIMARY response to an antigen.

Pentameric structure with a J chain- can bing to 10 different antigen binding sites.

What are the 2 Ab’s that have J chains? What is the function of a J chain?

IgMs
IgAs

J Chains is part of the Fc region and allows for the binding to mucosal sites

When are high amounts of IgG found? What is unique about these antibodies?

Predominant Ab found during secondary immune responses. Most abundant class in the serum (80% of antibodies) Only antibody that can cross the placenta

What is structurally important about IgAs and how does this affect where they are found? They also have one structural aspect that is unique to all 5 Abs. What is it? What is unique about this antibody in terms of how it may be transferred?

IgAs have J chains, which allow them to be found in mucosal sites. They also have a secretory component, which is not found in any other Ab. Can be transferred to newborns during breast feeding

What do IgE antibodies bind to and through what receptor?

Basophils and Mast cells via FceRI Elicit protection against helminths infections, asthma, and allergies

What are the 2 types of antibodies found on the membrane of B cells?

IgD | IgM

Which 2 antibodies and component(s) of the complement system initiates the classical pathway?

IgG and IgM C1q

What is the only receptor with inhibitory function of B cells?

FcyRIIB

What are the 4 non-covalent bonds used for Ag/Ab binding?

Hydrogen bonds Electrostatic bonds Van Der Waals Forces Hydrophobic Forces *Note that each of these bonds is weak, but together they have a high affinity interaction

What is the difference between Affinity and Avidity? Give an example of Ab that defines each.

Affinity- Strength of an interaction between an epitope of an antigen and the paratope of the antibody. Ex. IgG has a high affinity, but a low avidity. Avidity- Strength of the interaction between an antigen and an antibody. This is dependent on the affinities for each of the individual antigen binding sites and how many sites there are (Affinity + #binding sites). Ex. IgM has a high Avidity, but a low affinity

What is the definition of isotype switching?

Process by which the antibody class and binding affinity changes after the activation of a B cell. *Note that this requires T cell help