Chapter 18 - Practical Applications of Immunology Flashcards
What are some comon practical applications (uses) of immunology?
- Vaccination: inject Ag to trigger immune repsonse (make Ab)
- Serological Testing: test PT blood (serum) and look for Ag OR Ab (IgM) = timely and accurate diagnosis
Briefly describe how Vaccination works in regards to primary and secondary immune responses
- Injection of Ag will provoke a primary immune reponse -> formation of memory B cells and Ab (after clonal sel and exp)
- Will produce rapid, intense secondary immune response
A substance (Ag) that stimulates the immune system is known as a…
immunogen
This is described as protection for most of the population
Herd Immunity
Name 5 desirable characteristics for an ideal vaccine. Describe each
SEOOA
1. Vaccine Safety
- Vaccine must never be pathogenic/toxigenic
2. Vaccine Effectiveness
- Vaccine must be a strong immunogen (ex. protein) and stimulate immune system
3. Vaccine with Oral Administration
- Orally (painless) > injectable (painful)
4. Vaccine Require One Injection
- One injection/combination vaccine preferred (PT less likely to come back if req. multiple injection)
5. Vaccine is Affordable/Easily Accessible
- Availiable to most people @ resonable cost
Name the different Types of Vaccines (6)
- Live, attenuated vaccine
- Inactivated, killed vaccine
- Toxoid vaccines
- Conjugated vaccines
- Subunit vaccine
- mRNA (nucleic acid) vaccine
Compare these Types of Vaccines: Live, attenuated vaccine vs. Inactivated, killed vaccine
Include examples of DZ that use these types of vaccine
Live, attenuated vaccine
- Weakened pathogen
- Closely mimic actual infection (bc inj. Ag is still alive)
- Ex: MMR, Smallpox
Inactivated, killed vaccine
- Killed pathogen
- Safer (compared to live vaccines)
- Ex: Influenza, Polio
Describe: Toxoid vaccines, Conjugated vaccines, Subunit vaccines, mRNA (nucleic acid) vaccines
Toxoid vaccines
- inactivated toxin (make Ab against toxoid = antitoxin)
- immune response will target toxin
- Ex: Td vaccine
Conjugated vaccines
- main vaccine component is combined with a strong immunogen (protein)
- Ex: Pneumonia vaccine
Subunit vaccines
- Use antigenic fragments (piece of pathogen CW) to stimulate immune response
- Ex: Petussis vaccine; Hep. B vaccine
mRNA vaccines
- inject only bacterial/viral nucleic acid (NOT live pathogen)
-> inject mRNA into host cell -> make protein Ags -> stimulate immune response to make Ab - Ex: Covid vaccine
What part of the blood sample is being tested?
serum (no CF; top part)
YOU ARE NOT SAMPLING THE PLASMA (has CF)
When using serological testing, what are we looking for? (Hint: Theres two things we could look for)
Antigen or Antibody (IgM)
This is the study or diagnositc examination of blood serum (to see how the immune system response to pathogens or substances introduced into the body)
Serology
Name 5 desirable criteria for an ideal serological test
- High specificity/accuracy
- High sensitivity
- East set-up & interpretation
- High Throughput
- Affordable cost and Easy Access
Describe the criteria for an ideal serological test
High specificity/accuracy
- Unambigious (one interpretation)
- Reliable (100% accuracy)
- Ex: Pregnancy test; HIV test; athlete drug doping test
High sensitivity
- Uses small sample size = detect small quantities Ag or Ab
East set-up & interpretation
- test construction simple
- results easy to read (ex: color change; + or - symbol)
High Throughput
- Many tests carried out at once (bc machine automation) = fast results
Affordable cost and Easy Access
- Avalibale to most people @ reasonable cost
Define: Throughput
ability to stimultaneously test hundreds/thousands of samples
There are two types of serological tests. Name them and describe what you are looking for
Two Tests:
Direct Serological Test
- Look for Ag (pathogen)
Indirect Serological Test
- Look for Ab (IgM)
An antigen or antibody is provided either by the _____ sample or the ______ ______
patient
lab test
Understand what a serological test will have and what the PT serum sample would have to provide
If serological test has Ag, the PT serum sample will provide the Ab
If serological test has the Ab, the PT serum sample wil provide the Ag
Name (6) common examples of serological testing
- Precipitation Reactions
- Agglutination Reactions
- Neutralization Reactions
- Fluorescent-Antibody Technique
- Complement-Fixation Reactions
- ELISA
Describe this example of serological testing: Precipitation Reactions
Include: Types of testing avaliable, Component involved (Ag/Ab), Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications
Types of Testing Avaliable
- Direct Tests
- Indirect Tests
Component involved (Ag/Ab)
- Ag: soluble antigens (not attached to pathogen)
- Ab: IgG/IgM
Interpretation of Results
POSITIVE Direct Test:
- PT (serum sample) provide: Ag
- Lab provide: Ab
- PT provide soluble Ag -> Ab (lab) binds to Ag (PT) -> immune complex forms -> precipitan ring at equivalence zone = PT HAS DZ
POSITIVE Indirect Test:
- PT (serum sample) provide: Ab
- Lab provide: Ag
- PT provide Ab -> Ab (PT) binds to Ag (lab) -> immune complex forms -> precipitan ring at equivalence zone = PT has DZ
Clinical Applications
- VDRL Test
-> Blood test for Syphilis only
-> Look for PT Ab (against T. pallidum) = Indirect test - Lancefield Classification of Streptococcal Species
-> Classifies streptococci into groups from A-K and H-U (ex: GAS, GBS, GCS)
-> Helps distinguish between different species of Genus Streptococcus
In regards to precipitation reactions, just by looking at a test tube, how would you tell a PT has a disease?
immune complexes form at equivalence zone, where a precipitan ring is present.
precipital ring = cloudy line (immune complex present) where 1:1 ration of Ag to Ab
Describe this example of serological testing: Agglutination Reactions
Include: Types of testing avaliable, Component involved (Ag/Ab), Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications
Types of Testing Avaliable
- Direct Tests
- Indirect Tests
Component involved (Ag/Ab)
- Ag: particulate antigens (attached to pathogen)
- Ab: IgM
Interpretation of Results
POSITIVE Direct Test:
- PT (serum sample) provide: Ag
- Lab provide: Ab (IgM)
- Ag and IgM present = immune complex = clumping = POSITIVE TEST
POSITIVE Indirect Test:
- PT (serum sample) provide: Ab
- Lab provide: Ag
- Ag cand IgM present = immune complex = clumping = POSITIVE TEST
Clinical Applications
- Hemaggulitnation
-> For blood typing; Agglutination of RBC surface Ag & complimentary Ab - Antibody Quantitation
-> measuring Ab titer
-> Differentiate bw primary (high IgM) & secondary (high IgG) exposure
Know how to tell what blood type you have in regards to hemagglutination.
Ex: If you have two wells, one with anti-A Ab and one with anti-B Ab, what would you observe you placed a PT serum sample who has Type A blood into these two wells (hint: which wells would clump)?
Type A:
- Anti-A well: clumping
- Anti-B well: x
Type B:
- Anti-A well: x
- Anti-B well: clumping
Type AB:
- Anti-A well: clumping
- Anti-B well: clumping
Type O:
- Anti-A well: x
- Anti-B well: x
Describe this example of serological testing: Neutralization Reactions
Include: Types of testing avaliable, Component involved (Ag/Ab), Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications
Types of Testing Avaliable
- Indirect Tests
Component involved (Ag/Ab)
- Ag: Toxin/Virus
- Ab: Antitoxin/Antivirals
- Cell Indicator
Interpretation of Results
Toxin Neutralization Test: + Indirect Test:
- PT (serum sample) provide: Ab
- Lab provide: Ag (toxin) & cell indicator
- PT serum sample (has Ab) -> lab adds Ag and cell indicator -> PT Ab and Lab Ag form immune complex -> toxin is neutralized -> cell indicator is UNDAMAGED -> PT HAS DZ
- IF NEGATIVE: PT serum sample does NOT have Ab -> Lab adds Ag and cell indicator -> no Ab (PT) present -> toxin not neutralized -> toxin attack cell indicator -> cell indicator damage -> PT DOES NOT HAVE DZ
Viral Hemaggulitnation Inhibition Test: + Indirect Test:
- PT (serum sample) provide: Ab
- Lab provide: Ag (virus) & cell indicator (RBC)
- Pt serum sample (has Ab) -> lab adds Ag (virus) and cell indicator (RBC) -> PT Ab bind to lab Ag (virus) -> virus neutralized -> hemagglutinatoin inhibited -> NO CLUMPING -> PT HAS DZ
- IF NEGATIVE: PT serum sample (NO Ab) -> lab adds Ag (virus) and cell indicator (RBC) -> no Ab (PT) present-> virus not neutralized -> hemagglutinatoin of RBC ->YES CLUMPING -> PT DOES NOT HAVE DZ
Clinical Applications
- DX of bacterial disease (toxin production)
- DX of viral disease
Describe this example of serological testing: Fluorescent Antibody Reactions
Include: Types of testing avaliable, Component involved (Ag/Ab), Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications
Types of Testing Avaliable
- Direct Tests
- Indirect Tests
Component involved (Ag/Ab)
- Ag: Streptococci or T. Pallidum
- Ab: Fluorescent Ab or Anti-human Ab
Interpretation of Results
POSITIVE Direct Florescent-Antibody (FA) Test:
- PT (clinical/throat sample) provides: Group A streptococci (Ag)
- Lab provides: Fluorescent-Dyed Ab
- PT sample (has Group A streptococci Ag) -> lab adds fluorescent-dyed Ab -> Immune complex forms -> Fluorescent Streptococci (chains)-> POSITIVE, PT has DZ
- IF NEGATIVE: No fluorescent streptococci (chains)
POSITIVE Indirect Florescent-Antibody (FA) Test:
- PT (serum sample) provides: Ab
- Lab provide: T. pallidum (Syphilis) & Fluorescent Antihuman Ab (Ab that binds to human Ab)
- PT sample (has Ab against T. Pallidum) -> Lab adds Ag (T. pallidum) and Fluorescent Anti-human Ab -> Immune complex forms -> Fluorescent Antihuman Ab binds to PT Ab of immune complex-> fluorescent T. pallidum (spiral) -> POSITIVE, PT has DZ
- IF NEGATIVE: No flourescent T. pallidum (spiral)
Clinical Applications
- Identify GAS from throat sample (direct FA test)
-> Ex: diagnose strep throat/scarlet fever by looking for streptococcus pyogenes - See if T. pallidum from PT blood is producing Ab (indirect FA test)
-> Used to diagnose Syphilis
What types of serological tests (reactions) can be used to diagnose Syphilis? Are these direct or indirect tests?
VDRL Test (Precipitation RXN)
- Indirect test
Florescent-Antibody Test (Flourescnet Antibody Technique)
- Indirect Test
Describe this example of serological testing: Complement Fixation Reactions
Include: Types of testing avaliable, ALL Component involved, Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications, MISC
Types of Testing Avaliable
- Indirect Tests
Component involved
- Antibody (PT)
- Antigen (Lab)
- Complement Protein (Lab)
- Sheep RBC (Lab)
- Antibody to sheep RBC (Lab)
Interpretation of Results
POSITIVE Indirect Complement-fixation Test:
- PT (serum sample) provides: Ab
- Lab provide: Ag & complement
- YES PT has Ab -> Immune complex forms -> complement binds/fixed to stem region -> complement fixation (all complement used up/no more CP available)
- Add Sheep RBC & Ab to RBC -> NO hemolysis -> YES PT has DZ
NEGATIVE Indirect Complement-fixation Test:
- PT (serum sample) provides: No Ab
- Lab provide: Ag, complement, Sheep RBC, Anti RBC Ab
- No PT Ab = No immune complex forms -> No complement fixation (all complement available)
- Add Sheep RBC & (Ab to sheep RBC) -> complement binds to Sheep RBC Ab -> YES hemolysis -> red color -> NO DZ
Clinical Applications
- DX of bacterial DZ
- Dx of viral DZ
MISC
- Can detect small amounts of Ab = Highly SENSITIVE test
Name the two stages for the Complement Fixation RXN Test
What do these stages tell us?
Which parts (based on exam figures) happen in each stage?
1. Compliment fixation stage
- Tells us if complement gets fixed/used up
- Part 1 and 2
2. Indicator stage
- Tell us if PT is positive/negative for DZ
- Part 3 and 4
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 1 for a POSITIVE CF Test
- An Ag and inactivated complement are provided by the lab
- These are added to the serum sample containing the PT Ab which are specific for the Ag
- An immune complex will form consisting of the labs Ag and the PT Ab
- This is part of the “Compliment Fixation Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 2 for a POSITIVE CF Test
- As a result of immune complex formation, compliment gets activated and compliment fixation occurs (all availiable complement binds to antibody stem region of the immune complex)
- Since all of the complement got used up, no more compliment will be availiable to bind to future immune complex formations
- This is part of the “Compliment Fixation Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 3 for a POSITIVE CF Test
- A sheep RBC and Ab against sheep RBC are provided by the lab and are added to the PT serum sample
- The sheep RBC is used as a test indicator
- An immune complex will form between the sheep RBC and the Ab against sheep RBC
- This is part of the “Indicator Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 4 for a POSITIVE CF Test
- No hemolysis of sheep RBC occurs because compliment did not bind to the Ab against sheep RBC
- Compliment did not bind because it was all used-up and already fixed (complement fixation) in the earlier step to the first immune complex. Therefore, complement was no longer availiable
- This part is the “Indicator Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 1 for a NEGATIVE CF Test
- An antigen and inactivated complement are provided by the lab
- These are added to the serum sample that does NOT contain the PT antibodies which would have been specific for the antigen
- NO immune complex will forms because the PT serum sample has no Ab against the labs Ag
- This is part of the “Compliment Fixation Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 2 for a NEGATIVE CF Test
- As a result of NO immune complex formation, compliment does NOT get activated and compliment fixation does NOT occur (compliment does not bind to Ab stem region of the immune complex)
- Since NO complement got used up (since it did not bind to Ab stem region) all of the compliment will be availiable to bind to future immune complex formations
- This is part of the “Compliment Fixation Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 3 for a NEGATIVE CF Test
- A sheep RBC and Ab against sheep RBC are provided by the lab and are added to the PT serum sample
- The sheep RBC is used as a test indicator
- An immune complex will form between the sheep RBC and the Ab against sheep RBC
- This is part of the “Indicator Stage” of the test
In regards to the exam figure regarding Compliment-Fixation Reaction Test, describe what is going on in Stage 4 for a NEGATIVE CF Test
- YES hemolysis of sheep RBC occurs because compliment was activated and compliment fixation now occurs (all availiable complement binds to Ab stem region of immune complex)
- Compliment binds to Ab against sheep RBC because it was not used up/not fixed (no compliment fixation) in the earlier step because no immune complex formed during the Compliment Fixation Stage of the test. Therefore, compliment was availiable
- Hemolysis of sheep RBC indicates a negative test for the patients Ab, and thus, negative for the disease
- This part is the “Indicator Stage” of the test
Describe this example of serological testing: ELISA
Include: Types of testing avaliable, ALL Component involved (Ag/Ab), Interpretation of Results (What does the PT/Lab provide, Know what a positive/negative test looks like), Clinical Applications, MISC
Types of Testing Avaliable
- Direct Test
- Indirect Tests
Component involved
Direct ELISA:
- (HIV) Ag (PT)
- Adsorbed Ab (Lab)
- Enzyme-Linked Ab (Lab)
- Substrate (Lab)
Indirect ELISA:
- (HIV) Adsorbed Ag (Lab)
- Ab (PT)
- Enzyme-Linked Antihuman Ab (Lab)
- Substrate (Lab)
Direct ELISA (Pregnancy Test):
- hCG hormone from urine sample (PT)
- 2 Monoclonal Ab for hCG (test)
Interpretation of Results
POSITIVE Direct Test HIV Testing
- PT (serum sample) provides: HIV Ag
- Lab Provides: Adsorbed Ab, Enzyme-linked Ab, substrate
- Lab Ab adsorbed to well -> immune complex forms -> Enz-linked binds to Ag forming sandwich -> enz substrate added -> RXNS occur color change to purple
POSITIVE Indirect Test HIV Testing
- PT (serum sample) provides: Ab
- Lab Provides: Adsorbed HIV Ag, Enzyme-linked Anti-human Ab, substrate
- Lab HIV Ag adsorbed to well -> PT serum sample added-> immune complex forms -> Enz-linked Antihuman Ab binds to Ab-> enz substrate added -> RXNS occur color change to purple
POSITIVE Direct Test At Home Pregnancy Test
- PT (urine sample) provides: hCG hormone
- Test provides: Captured Ab bound to substrate
- Urine sample added -> both monoclonal Ab bind to hCG hormone-> sandwich form -> color change/line forms
Clinical Applications
- Home pregnancy test (direct ELISA)
- Drug testing (direct ELISA)
- HIV testing (direct ELISA)
- HIV Testing after seroconversion (indirect ELISA)
MISC
- High specificity
- High sensitivity
Name serological tests that are have high sensitivity (4), intermediate sensititivty (2), and low sensitivity (1)
High Sensitivity
- Radioimmunoassay
- PCR
- Compliment-Fixation Test
- ELISA
Intermediate Sensitivity
- Agglutination RXN
- Neutralization RXN
Low Sensitivity
- Precipitation RXN
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 1 for a POSITIVE DIRECT ELISA Test
- Antibody (against Ag/HIV) from the lab is adsorbed to well
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 2 for a POSITIVE DIRECT ELISA Test
- PT sample (containing HIV) is added to the well containing the adsorbed Ab against HIV (from lab)
- An immune complex will form between PT HIV and the adsorbed Anti-HIV Ab
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 3 for a POSITIVE DIRECT ELISA Test
- An enzyme-linked Ab (specific to HIV) from the lab is added into a well containing an immune complex between the adsorbed Ab from the lab and the PT HIV.
- The enzyme-linked Ab binds to the PT HIV (Ag) which is a part of an immune complex
- This orientation/formation is known as a sandwich.
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 4 for a POSITIVE DIRECT ELISA Test
- The enzyme’s substrate from the lab is added
- The substrate will bind to the enzymes of the enzyme-linked antibody and this reaction produces a product that results in a visible color change
- This indicates that the PT is POSITIVE for HIV.
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 1 for a POSITIVE INDIRECT ELISA Test
- HIV (Ag) from the lab is adsorbed to the well
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 2 for a POSITIVE INDIRECT ELISA Test
- PT sample (containing Ab against HIV) is added to the well containing the adsorbed HIV (Ag) from the lab
- An immune complex will form between the PT Anti-HIV Ab and the absorbed HIV (Ag)
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 3 for a POSITIVE INDIRECT ELISA Test
- An enzyme-linked anti-human Ab from the lab is added into a well containing an immune complex between the adsorbed HIV (from lab) and the PT Ab against HIV.
- The enzyme-linked anti-human Ab binds to the PT Ab against HIV that is a part of an immune complex
(NO SANDWICH FORMATION OCCURS IN INDIRECT ELISA)
In regards to the exam figure regarding ELISA Testing, describe what is going on in Step 4 for a POSITIVE INDIRECT ELISA Test
- The enzyme’s substrate from the lab is added
- The substrate will bind to the enzymes of the enzyme-linked anti-human Ab and this reaction produces a product that results in a visible color change
- This indicates that the PT is POSITIVE for HIV.