ABO STUDY SHEET Questions with Correct Answers (Grade A+)
Question 1: ABO Blood Group System
Answer: individuals are expected to have naturally occurring antibodies in their serum to antigens that are
absent from their RBCs ex: Type A -> have A antigen on RBC and B antibodies in serum
Question 2: Landsteiner Theory
Answer: inverse reciprocal relationship between forward and reverse typing have ABO antigen -> don't
have serum antibody have serum antibody -> don't have ABO antigen
Question 3: Front Typing Antibody
Answer: purchased antibody reagents (anti-A and anti-B)
Question 4: Front Typing Antigen
Answer: unknown antigen on RBCs
Question 5: Front Typing Procedure
Answer: 1. label tubes A and B 2. Add reagents -purchased known monoclonal antibodies (blue anti-A and
yellow anti-B) 3. Add pt RBCs - unknown antigen on RBC surface 4. Mix well and Centrifuge according to
SOP 5. Gently rock each tube until the cell suspension or button is completely resuspended from the bottom
of the tube 6. Look at tube label, grade the reactions, and record the results in the logbook immediately after
reading each tube
Question 6: Reverse Typing Antibody
Answer: unknown antibodies from pt serum
Question 7: Reverse Typing Antigen
Answer: purchased known antigen on RBC surface (A1 and B RBCs)
Question 8: Reverse Typing Procedure
Answer: 1. label tubes a and b 2. add patient serum (unknown antibodies) 3. add reagents (purchased known
antigen on RBCs - A1 and B) 4. Mix well and Centrifuge according to SOP 5. Gently rock each tube until
the cell suspension or button is completely resuspended from the bottom of the tube 6. Look at tube label,
grade the reactions, and record the results in the logbook immediately after reading each tube
Question 9: Front Typing Results
Answer: agglutination = antigen for specific antibody is present (form visible AbAg complex) Anti-A: type
A and AB Anti-B: type B and AB
Page 1
,Question 10: Which ABO blood types will agglutinate when front typed with Anti- A?
Answer: type A and AB
Question 11: Which ABO blood types will agglutinate when front typed with Anti- B?
Answer: type B and AB
Question 12: Reverse Typing Results
Answer: agglutination = antibody for known antigen is present (form complex with pt antibody and reagent
antigen) A1 cells: Type O and B B cells: Type O and A
Question 13: Which ABO blood types will agglutinate when reverse typed with A1 cells?
Answer: types O and B (have antibody against A)
Question 14: Which ABO blood types will agglutinate when reverse typed with B cells?
Answer: type O and A (have antibody to B)
Question 15: Agglutination Grading
Answer: 4+ = one solid agglutinate (clump_ 3+ = several large agglutinates - clear backgorund 2+ = several
small-medium sized clumps - clear background 1+ = very small (tiny) agglutinates - red or turbid
background 0 = negative W/m = microscopic only H = hemolysis
Question 16: IgM
Answer:
1. most common in ABO
2. complete antibody (pentamere)
3. can bridge easier between RBC antigens (agglutination)
4. binds complement well
Question 17: IgG
Answer: -incomplete antibody (monomere) -too small to bridge RBC antigens well (sensitization = invisible
AgAb complex @ 37ºC) (add AHG -> visible agglutination) -doesnt bind complement well -able to cross
the placenta
Question 18: ABO Antibodies
Answer: Naturally occurring (produced w/o prior exposure) Typically IgM Binds complement well (Can
cause rapid intravascular hemolysis) Wide thermal range (Room Temp, 4ºC, 30-37ºC) Titers: Newborn <
3-6 Mos < 5-10 yrs (Peak) > Adult > Elderly Group O Individuals: Predominantly IgG, but also IgM
Anti-A,B, Anti-A & Anti-B
Page 2
, Question 19: What would a front type of a type O patient look like?
Answer: anti-A: 0 anti-B: 0
Question 20: What would a front type of a type A patient look like?
Answer: anti-A: 4+ anti-B: 0
Question 21: What would a front type of a type B patient look like?
Answer: anti-A: 0 anti-B: 4+
Question 22: What would a front type of a type AB patient look like?
Answer: anti-A: 4+ anti-B: 4+
Question 23: In reverse typing, what results would you expect on a type O patient?
Answer: A1 cells: 4+ B cells: 4+
Question 24: In reverse typing, what results would you expect on a type A patient?
Answer: A1 cells: 0 B cells: 4+
Question 25: In reverse typing, what results would you expect on a type B patient?
Answer: A1 cells: 4+ B cells: 0
Question 26: In reverse typing, what results would you expect on a type AB patient?
Answer: A1 cells: 0 B cell: 0
Question 27: What do the A, B, and O genes code for?
A. the corresponding antigen
B. sugar
C. Rh factor
D. glycosyltransferase
Answer: d. glycosyltransferase (codes for glycosyltransferase enzyme that adds a specific sugar to a basic
precursor substance)
Question 28: What is meant by codominant expression of the A, B, and O genes?
Answer: two different alleles are inherited at the same genetic location (i.e, one allele from mom and a
different one from dad), and the products of BOTH of the alleles are expressed. both A and B expressed
Page 3
Question 1: ABO Blood Group System
Answer: individuals are expected to have naturally occurring antibodies in their serum to antigens that are
absent from their RBCs ex: Type A -> have A antigen on RBC and B antibodies in serum
Question 2: Landsteiner Theory
Answer: inverse reciprocal relationship between forward and reverse typing have ABO antigen -> don't
have serum antibody have serum antibody -> don't have ABO antigen
Question 3: Front Typing Antibody
Answer: purchased antibody reagents (anti-A and anti-B)
Question 4: Front Typing Antigen
Answer: unknown antigen on RBCs
Question 5: Front Typing Procedure
Answer: 1. label tubes A and B 2. Add reagents -purchased known monoclonal antibodies (blue anti-A and
yellow anti-B) 3. Add pt RBCs - unknown antigen on RBC surface 4. Mix well and Centrifuge according to
SOP 5. Gently rock each tube until the cell suspension or button is completely resuspended from the bottom
of the tube 6. Look at tube label, grade the reactions, and record the results in the logbook immediately after
reading each tube
Question 6: Reverse Typing Antibody
Answer: unknown antibodies from pt serum
Question 7: Reverse Typing Antigen
Answer: purchased known antigen on RBC surface (A1 and B RBCs)
Question 8: Reverse Typing Procedure
Answer: 1. label tubes a and b 2. add patient serum (unknown antibodies) 3. add reagents (purchased known
antigen on RBCs - A1 and B) 4. Mix well and Centrifuge according to SOP 5. Gently rock each tube until
the cell suspension or button is completely resuspended from the bottom of the tube 6. Look at tube label,
grade the reactions, and record the results in the logbook immediately after reading each tube
Question 9: Front Typing Results
Answer: agglutination = antigen for specific antibody is present (form visible AbAg complex) Anti-A: type
A and AB Anti-B: type B and AB
Page 1
,Question 10: Which ABO blood types will agglutinate when front typed with Anti- A?
Answer: type A and AB
Question 11: Which ABO blood types will agglutinate when front typed with Anti- B?
Answer: type B and AB
Question 12: Reverse Typing Results
Answer: agglutination = antibody for known antigen is present (form complex with pt antibody and reagent
antigen) A1 cells: Type O and B B cells: Type O and A
Question 13: Which ABO blood types will agglutinate when reverse typed with A1 cells?
Answer: types O and B (have antibody against A)
Question 14: Which ABO blood types will agglutinate when reverse typed with B cells?
Answer: type O and A (have antibody to B)
Question 15: Agglutination Grading
Answer: 4+ = one solid agglutinate (clump_ 3+ = several large agglutinates - clear backgorund 2+ = several
small-medium sized clumps - clear background 1+ = very small (tiny) agglutinates - red or turbid
background 0 = negative W/m = microscopic only H = hemolysis
Question 16: IgM
Answer:
1. most common in ABO
2. complete antibody (pentamere)
3. can bridge easier between RBC antigens (agglutination)
4. binds complement well
Question 17: IgG
Answer: -incomplete antibody (monomere) -too small to bridge RBC antigens well (sensitization = invisible
AgAb complex @ 37ºC) (add AHG -> visible agglutination) -doesnt bind complement well -able to cross
the placenta
Question 18: ABO Antibodies
Answer: Naturally occurring (produced w/o prior exposure) Typically IgM Binds complement well (Can
cause rapid intravascular hemolysis) Wide thermal range (Room Temp, 4ºC, 30-37ºC) Titers: Newborn <
3-6 Mos < 5-10 yrs (Peak) > Adult > Elderly Group O Individuals: Predominantly IgG, but also IgM
Anti-A,B, Anti-A & Anti-B
Page 2
, Question 19: What would a front type of a type O patient look like?
Answer: anti-A: 0 anti-B: 0
Question 20: What would a front type of a type A patient look like?
Answer: anti-A: 4+ anti-B: 0
Question 21: What would a front type of a type B patient look like?
Answer: anti-A: 0 anti-B: 4+
Question 22: What would a front type of a type AB patient look like?
Answer: anti-A: 4+ anti-B: 4+
Question 23: In reverse typing, what results would you expect on a type O patient?
Answer: A1 cells: 4+ B cells: 4+
Question 24: In reverse typing, what results would you expect on a type A patient?
Answer: A1 cells: 0 B cells: 4+
Question 25: In reverse typing, what results would you expect on a type B patient?
Answer: A1 cells: 4+ B cells: 0
Question 26: In reverse typing, what results would you expect on a type AB patient?
Answer: A1 cells: 0 B cell: 0
Question 27: What do the A, B, and O genes code for?
A. the corresponding antigen
B. sugar
C. Rh factor
D. glycosyltransferase
Answer: d. glycosyltransferase (codes for glycosyltransferase enzyme that adds a specific sugar to a basic
precursor substance)
Question 28: What is meant by codominant expression of the A, B, and O genes?
Answer: two different alleles are inherited at the same genetic location (i.e, one allele from mom and a
different one from dad), and the products of BOTH of the alleles are expressed. both A and B expressed
Page 3
