5 Written Questions

1. elution
2. False negatives that may cause errors with AHG testing
3. monoclonal AHG production
4. negative result for DAT
5. antibody (antiglobulin)

5 Matching Questions

1. (22% bovine) reduces the negative charge of the RBCs allowing them to move closer and to enhance direct agglutination by some antibodies of the IgG class; routinely used reagent & invariably requires some incubation time to be effective
2. temperature, incubation time, pH, antigen-antibody ratio (zone reactions)
3. disadvantages include
   -low specificity
   -low titer
4. most commonly employed media for detecting and identifying IgM antibodies; tends to cluster around and partially neutralize oppositely charged sites on antigen and antibody molecules causing an increase in the uptake of IgM antibodies
5. denotes that RBCs are coated with antibody or complement

1. a factors effecting agglutination
2. b albumin
3. c disadvantages of polyclonal AHG production
4. d sensitization
5. e saline

5 Multiple Choice Questions

1. DAT (Direct Coombs Test)
   1. includes Anti IgG, Anti C3, Anti C3b, Anti C3d and Anti C4
   2. test designed to detect antigen-antibody complexes that have formed "in-vivo"
   3. test designed to detect incomplete (nonagglutinating) antibodies to potential donor red cells (compatibility testing) or to screening cells (antibody screen) in serum; detects in-vitro sensitized red cells
   4. temperature, incubation time, pH, antigen-antibody ratio (zone reactions)
2. Polyethylene Glycol (PEG)
   1. used as an additive to increase antibody uptake; removes water, increasing antibody concentration; used to separate IgM from IgG when multiple antibodies are suspected
   2. reagent that accelerates antibody uptake, which is 1st stage of agglutination; works by lowering ionic strength of reaction media (NaCl), reducing the "shielding effect" of RBCs that normally hinder antibody uptake; addition of this reagent shortens incubation time required for detection of most antibodies; may or may not require incubation; used as substitute for saline and albumin
   3. includes Anti IgG, Anti C3, Anti C3b, Anti C3d and Anti C4
   4. substance that will enhance antigen-antibody interactions; work by adjusting the zeta potential, which is the difference in charge of the ionic cloud that surround red cells in an electrolyte solution
3. polybrene
   1. derived from one line of plasma cells and only recognize one epitope
   2. positively charged polymer that causes normal RBCs to aggregate spontaneously by neutralizing negative surface charge contributed by sialic acid; can be used to detect ABO incompatibiliy
   3. denotes that RBCs are coated with antibody or complement
   4. (22% bovine) reduces the negative charge of the RBCs allowing them to move closer and to enhance direct agglutination by some antibodies of the IgG class; routinely used reagent & invariably requires some incubation time to be effective
4. monospecific AHG
   1. includes Anti IgG, Anti C3, Anti C3b, Anti C3d and Anti C4
   2. another name for antiglobulin test
   3. denotes that RBCs are coated with antibody or complement
   4. temperature, incubation time, pH, antigen-antibody ratio (zone reactions)
5. False positives that may cause errors with AHG testing
   1. Disadvantages include:
      -over-specificity (only recognize single epitope)
      -overly sensitive
      -complement fixation may not initiate
   2. false negatives include
      -complement-dependent antibodies may not be detected if anticoagulated plasma or old serum is used
      -poor washing that causes neutralization of antiglobulin reagent
      -contamination of reagent w/ human globulins
      -elution of the antibody during washing
      -use of an incorrect incubation temp
      -improper concentration of cells and serum
      -omitting the antiglobulin sera
      -under centrifugation
   3. advantages include
      -more likely to pick up genetic variants
      -cheaper
   4. False postives include
      -bacterial contamination of cells leading to T-activation
      -saline and glassware contaminated w/ silica particle or other debris and dirt
      -over-centrifugation
      -extreme retics may cause false positve DAT as the transferrin is attached to the retic membrane
      -cells that are positive by the direct antiglobulin test cannot be used in an indirect test
      -false positive DAT tests on refrigerated specimens

5 True/False Questions

1. cells agglutinate in the antiglobulin sera that indicates that antigen-antibody reaction occurred during incubation → postive result for IAT

   True        False

2. produced by injecting animals w/ human globulin components & then collecting the antihuman antibodies; more than one spleen lymph w/ill produce immunoglobulins; sera made from these animals will be directed against MULTIPLE epitopes → polyclonal AHG production

   True        False

3. substance that is capable of eliciting an immune response, which is normally a foreign substance → potentiator

   True        False

4. =most important media used to detect IgG antibodies
   =produced by injecting rabbit w/ purified human gamma globulin (IgG) which stimulates animal to produce antibodies against foreign human protein
   =will react with globulins that are either bound to RBCs or freely circulating in the serum
   =additon of media to washed RBCs that are "coated" w/ antibodies will cause agglutination by forming a bridge b/t antibodies that are attached to RBCs
   =will react w/ globulins that are bound to RBCs or are circulating freely in serum; easily neutralized by free globulin in serum, plasma, reagents or other extraneous substances
   =neutralization results in false neg reactions → sensitization

   True        False

5. advantages include
   -more likely to pick up genetic variants
   -cheaper → disadvantages of polyclonal AHG production

   True        False