13- Clinical And Laboratory Immunology Flashcards
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
Serology
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
