Immunology III - Coplan Flashcards
How does passive immunity occur?
- Naturally (Maternal Abs transferred to fetus through placenta)
OR - Artificially (Human immunoglobulin specific to toxin or antigen given to pt)
When is passive immunization used?
When risk of infection is high & body has insufficient time to develop immune response
Vaccine administration stimulates what?
Artificially acquired active immunity
How is blood type determined?
By presence or absence of RBC antigens
Define: agglutination
Antibody binding to antigen –> RBC clumping
Type A blood characteristics
- A antigens
- Anti-B antibodies
Type B blood characteristics
- B antigens
- Anti-A antibodies
Type AB blood characteristics
- A & B antigens
- No antibodies
Type O blood characteristics
- No antigens
- Anti-A & anti-B antibodies
Rh
- A surface antigen
- If present = Rh +
- If absent = Rh -
What happens w/ Rh in pregnancy?
- If mom is Rh- & fetus is Rh+, fetal maternal blood mixes –> mom can develop antibodies to the Rh antigen of the fetal blood
- Mom’s antibodies can cross placenta & attack RBCs of the fetus –> fetus at risk for hemolytic disease of the newborn (erythroblastosis fetalis)*
Indirect coombs test
- Mom’s blood drawn & mixed w/ Rh+ RBCs
- Coomb’s serum is added –> agglutination if Abs present
- If mom has antibodies to Rh antigen –> agglutination will occur
What do you do if initial screening test is negative?
Repeat at 28-30 wks & 36 wks gestation
How do you prevent hemolytic disease in subsequent pregnancies?
Give mom RhoGAM immediately after delivery
Who is the universal donor?
O-
Who is the universal recipient?
AB+
What is the most common blood type?
O+ = 38% A+ = 34%
What blood is most rare?
AB- = 1%
Prick skin testing
- Detects specific IgE antibodies to allergens
- Those allergic to allergin –> B cells differentiate & produce IgE
- IgE binds to mast cells
- Repeat exposure –> release of histamine –> wheal & flare rxn
What does the RAST test detect?
Specific IgE antibody in serum
RAST test method
- Known antigen is coupled to a paper disk
- Serum added
- If pt has specific IgE antibodies, they bind to antigen (test will be positive)
- Radio-labeled anti-IgE antibody added
- Radioactive anti-IgE binds to the specific IgE (if present) & radioactive emissions are counted
What does viral load detect?
Presence of virus
What tests are used to detect antibodies?
ELISA & Western Blot
*May be negative during 1st few wks of infection
What does a titer measure?
- Concentration of an antibody, as determined by finding highest dilution at which it is still able to cause agglutination of antigen
A higher titer indicates what?
More antibody is present
What is a titer used for?
Following the course of infection
Rapid Plasma Reagin (RPR) - What does this detect?
Syphilis (Treponema pallidum)
What does “reagin” mean?
Test does not detect antibodies against the actual bacterium, but for antibodies against substances released by cells when they are damaged
What is a decreasing titer used for?
Monitoring tx success
How is syphilis confirmed?
FTA-ABS test
What does the FTA-ABS test detect?
- Antibodies specific to Treponema bacterium
* Becomes positive 4-6wks after inoculation
What does ASO titer indicate?
Body’s rxn to group A beta-hemolytic strep
What is the ASO test used for?
To determine whether a previous strep infection has caused a post-strep disease
What enzyme is produced by the streptococcus organism?
Streptolysin O
What does streptolysin O do?
- Acts as an antigen
- Body produces antibody to it - aka ASO
When are titers the highest?
3 wks after infection
When will most titers return to normal?
By 6 months
When does HSV IgM antibody production begin?
Several days after primary HSV infection
When does HSV IgG antibody production begin?
After HSV IgM production
NAATs or NATs
- Biochemical technique used to detect the genetic material of an infecting organism
- Antigen tests help shorten “window period”
- Positive before antibody tests are positive
- Take less time than a culture
