| Question | Answer |
| IgG vs. IgM | IgG vs. IgM |
| Structure of IgG | monomer |
| structure of IgM | pentamer |
| number of binding sites | IgG=2 igM=10 |
| type of antibody of IgG | immune |
| type of antibody of IgM | natural occurring |
| Optimum temp of reactivity IgG | 37 |
| ABO DISCREPENCIES | ABO DISCREPENCIES |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
0 0 0 0 0 0 0
possible causes and resolution | cause: missing isoagglutinins
resolution: 1. repeat reverse typing with 4 drops of serum
2. incubate at room temp 30 mins
3. run auto control and sreening cells |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
4+ 0 1+ 0 4+ 0 0 | possible cause: A2 with anti-A1
resolution: 1. type with anti-A1
2. test serum with additional A1 and A2 cells |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
4+ 4+ 2+ 2+ 2+ 2+ 2+ | possible cause: rouleaus
resolution: 1. use washed RBC's cells in saline for forward grouping
2. Perform saline replacement tech in reverse grouping |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
3+ 4+ 1+ 0 0 0 0 | possible cause: A2 B with anti-A1
resolution: 1. type cells with anti-A1.
2 test serum with additional A1 and A2 cells. |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
4+ 2+ 0 0 0 0 0 | possible cause: acquired B antigen.
resolution:1. check medical history for GI problen or septicemia. 2. type with human anti-B acidifed to pH 6.0 or monoclonal anti-B. |
| anti-A, Anti B, A1, A2, B cells, O cells,auto
4+ 4+ 2+ 0 0 2+ 0 | possible cause: AB with cold alloantibody.
resolution: 1. Perform antibody panel. 2. Repeat forward grouping with B cells lacking the corresponding antigen. |
| ABO TYPING | ABO TYPING |
| ANTI-A, ANTI-B, A CELLS, B CELLS
0 0 + + | GROUP O |
| ANTI-A, ANTI-B, A CELLS, B CELLS
+ 0 0 + | GROUP A |
| ANTI-A, ANTI-B, A CELLS, B CELLS
0 + + 0 | GROUP B |
| ANTI-A, ANTI-B, A CELLS, B CELLS
+ + 0 0 | GROUP AB |
| ABO SYSTEM | ABO SYSTEM |
| ANTIGENS ON RBC ANTIBODY IN SERUM
neither Anti-A, Anti-B | GROUP O |
| ANTIGENS ON RBC ANTIBODY IN SERUM
A Anti-B | GROUP A |
| ANTIGENS ON RBC ANTIBODY IN SERUM
B Anti-A | GROUP B |
| ANTIGENS ON RBC ANTIBODY IN SERUM
A and B Neither anti-A nor anti-B | GROUP A and B |
| ABO GENOTYPES/PHENOTYPES | ABO GENOTYPES/PHENOTYPES |
| PHENOTYPE A | AA, AO |
| PHENOTYPE B | BB, BO |
| PHENOTYPE AB | AB |
| PHENOTYPE O | OO |
| DIRECT (DAT) vs. INDIRECT (IAT) | DIRECT (DAT) vs. INDIRECT (IAT) |
| in-vivo sensitization of RBC's by IgG antibody is dettected by DAT or IAT | DAT |
| In vitro sensitization of RBC's by IgG antibody is detected by DAT or IAT | IAT |
| What specimen is used for DAT | EDTA |
| does DAT require incubation | NO |
| What specimen is used for IAT | serum, plasma or RBC's |
| DAT detects what (4) | 1. Hemolytic disease of the newborn
2. transfusion reactions
3. autoimmune hemolytic anemia
4.drug-induced hemolytic anemia |
| IAT detects what (4) | 1. antibody screen
2. crossmatch
3. RBC phenotyping
4. weak D testing (Du) |
| DAT false positives: (6) | 1. complement binding in vitro if RBC's taken from a red top and AHG used.
2. septicemia
3. contamination of specimen
4. Wharton's jelly in cord blood
5. overreading
6. overcentrifugation |
| IAT false positives: (2) | 1. cells with positve DAT
2. Overcentrifugation |
| DAT false negatives: (6) | 1. interrupting testing
2. contamination, improper storage, outdated AHG.
3. Failure to add AHG
4. Neutralization of AHG
5. Dilution of AHG by residual saline
6. over/undercentrifugation |
| IAT false negatives: (same as DAT) plus: | over/under incubation |
