13- Clinical And Laboratory Immunology Flashcards Preview

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Flashcards in 13- Clinical And Laboratory Immunology Deck (21):

What are the features of an effective vaccine?

1) safe: vaccine must not cause illness or death itself
2) protective: must protect against illness resulting from exposure to live antigen
3) gives sustained protection: B and T cell activation (result in memory cells)
4) induces neutralizing antibody: prevent infection of cells that cannot be replaced (neurons)
5) induces protective T cells: pathogens better dealt with by cell mediated (such as intracellular)
6) practical: low cost per dose, stable biologically, easily administered, few side effects


What is agglutination?

The clumping of INSOLUBLE particles

cross-linking of antibodies with particulate antigens causes agglutination

Ex: RBC typing, diagnosing pneumococcus, meningitis, etc.


What is precipitation?

Aggregation of SOLUBLE molecules


Describe immunodiffusion

Determines the optimal antibody and antigen concentrations

-A precipitation test
-Serological test
-antigens and antibody mixed in proper proportion form precipitates= pull out soluble antigens

Precipitation test (antibody and antigen in separate wells) distance traveled~concentrations



Study of serum and other bodily fluids

In practice, refers to diagnostic identification of antibodies in serum


Compare active, passive, natural, and artificial immunity

Active: own response
Passive: other response/ result of someone else's
Natural: your response creates memory
Artificial: given to you

Active natural=getting sick (memory)
Active artificial= live vaccines (memory)
Passive natural= breastfeeding (no memory)
Passive artificial= antitoxins (given antibodies but not the immunity, no memory)


Describe a precipitation test

Antibody and antigen are put in. Separate wells

Equivalence point is where precipitation occurs

Concentration is comparable to distance travelled from starting point (because they must dilute to correct amounts)


Describe radial immunodiffusion

Determined the concentration of an antigen in an unknown sample when compared to known concentrations

Same principle as precipitation test, but now have different wells

Larger diameter ring of precipitation means higher concentration of antigen

Measure all diameters, plot, estimate


Describe complement fixation: what does it do?

-Based on generation of membrane attack complexes during complement activation
-detect presence of specific antibodies in an individual's serum
-can detect amounts too small to detect by agglutination


Describe complement fixation: how does it work/ Los-neg result?

1) compliment to patient serum and control
2) add antigen to both
3) patient serum is C-fixed, control is not
4) add sheep RBC and anti-sheep RBC antibodies
patient serum: complement is already fixed, so sheep RBC and antibody agglutinate (AGGLUTINATION = +)
Control: complement fixed to sheep blood antibodies--> negative test has not agglutination and blood is dispersed in sample


Describe RIA

Like ELISA, main difference is that RIA has a radioactive label

Stands for radioimmunoassay

Very sensitive, can quantify and detect amounts of antibody or antigen

Used to detect hormones, drugs, infectious agents, or antibodies


Describe ELISA

If have antigen, detect antibody, or vice versa

Initial screening test for HIV

Stands for enzyme-linked immunosorbent assay

Difference from RIA: chromates or fluorescent tag!


Describe western blotting

Technique to detect antibodies against multiple antigens

Advantages: can detect more types of antibodies, less subject to misinterpretation

Looks like gel electrophoresis


Describe FACS

Fluorescence activated cell sorter

Mix of cells are labeled with fluorescent antibody

Sorts and shows in graph which antibodies/cells are most concentrated

Think of graph as quadrants
IgM: immature B cells
Both IgM and IgB: mature b
Neither: non B cell
IgD is unlikely


What are some agglutination tests?

Blood typing: well that agglutinates is positive and has that blood antigen, no agglutination means negative for that antigen

Coombs test: another blood test to see if mother has antibodies against fetal RBCs

Positive for indirect or direct: issue the drug


Live attenuated verses dead inactivated?

Live attenuated: weakened, cannot complete replication cycle, cannot cause infection, helps innate response to respond better, intranasal flu is example

Dead inactivated: things too dangerous for live


How does a titer work?

Serial dilution agglutination test to see if somebody has immunity

Test blood when sick and recovered:
-Sick=acute phase serum
-Recovered= convalescent phase serum

Want to increase titer AT LEAST 4 FOLD FROM SICK TO RECOVERED (agglutination at smaller antigen concentration)


Monoclonal vs polyclonal antibodies?

Monoclonal: product of a single B cell clone, mono specific: only react with target epitope
-good for treatment and diagnostics

-due to multiple clones
-good for animal, bad for lab tests due to false positives
-often produce high titers (last visible dilution)
-but may cross react


How are monoclonal antibodies generated?

Combine nonhuman/animal (often mouse) spleen cells producing antibody m, immunized with antigen A WITH immortal cells lacking antibody secretion and the enzyme HGPRT

Result: cells that don't die AND make single antibody


Antibody types:


Omab:fully mouse antibody
Ximab: chimeric: human constant, mouse variable regions
Zumab: humanized, only hyper adorable regions are mouse, rest human
Umab: fully human


3 categories of immune suppressive drugs

1) Anti-inflammatory: over counter, antihistamines, corticosteroids, n-SAIDS
2) cytotoxic drugs: inhibit DNA synthesis, often for cancer, azathriopine interferes with CD8 costim
3) fungal and bacterial derivatives: inhibit T cell signaling, used for transplant stuff