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
