BLD 435 EXAM 2 QUESTIONS AND ANSWERS WITH COMPLETE
SOLUTIONS VERIFIED GRADED A++ LATEST UPDATE
recognize ABO and Rh discrepancies and determine the general cause of the
problem ie. weak ab, weak ag, extra ab extra ag.
Normal: Forward and reverse must agree
Forward typing must be a 4+
Reverse typing must be at least a 3+
Rh should be at least a 2+
----------------------------------------
if doesn't match you have a problem
if controls are + you have a problem
decide are you missing an antigen or is it just weak --> if strong forward its probably
correct then look at the serum
are you missing an antibody or is it just week
do you have extra antibody or antigen
2. compare and contrast the major subgroups of A antigens against the usual A
antigens. Include expected serological testing results for the subgroups A2, A3
and weaker subgroups collectively. Recognize serological results which are
characteristic of subgroups.
,16. define ABO subgroup. Explain how subgroups may be detected, including a
description of any special reagents.
All group A antigens are not the same, there are A subgroups
- the A we normally think of is A1
- There is also A2, A3,.....
A1 is 80%
A2 is 20%
Doesnt leave much room for the rest, they are not common but do show up
A1 and A2 are major subgroups of blood group A. These are differentiated by the
reaction of anti-A1 lectin with A1 cells. Rarely, significance of weaker variants like A2,
A3 and Ax is important as they may cause haemolytic transfusion reactions. A2 and
A2B are rare subgroups. Individuals having these subgroups do not recognize A1
antigens as their own hence, make up specific anti A1 antibody against A1 cells.
A2 is both qualitative (composition) and quantitative (#'s)
A2 is different enough from A1 that A2's can make an anti-A1
Non-A1: 1-8%
non-A1B: 22-35%
------------------------------
how to tell A1 for Asubs
- use reagent that agglutinates only A1 cells and not others
- A1 lectin or absorbed anti-A1
Principle
,A2 and weak A subgroups can possess an anti-A1 in serum or plasma, which will react
with A1 reagent cells during reverse or serum grouping. Anti-A1 is a common cause of
ABO discrepancies in A2 and weak A subgroups.
Specimen
Red cells and serum or plasma to be evaluated.
Reagents
1. Dolichos biflorus lectin (anti-A1).
2. Group A1, A2, and O control red cells.
Interpretation
1. The lectin should strongly agglutinate A1 red cells (3+ to 4+) but should not
agglutinate A2 or O red cells. Group A red cells that fail to agglutinate with the
lectin can be considered A2 or another weak A subgroup.
2. Anti-A1 in the patient’s serum will agglutinate all A1 samples. Anti-A1 will not
agglutinate autologous, A2, or group O red cells. If the patient’s serum agglutinates
group A2 or group O red cells, another cause for unexpected reactivity should be
investigated.
If commercial lectin preparations are used, the manufacturer’s directions should be
followed for appropriate testing method and controls
A3 always gives a mixed field agglutination
What is the A1 lectin?
from plant seeds, agglutinate red cells, not an antibody but acts like one
** Dolichus biflorus **
, Anti-A1 Absorbed: agglutinates A1 cells, but reacts negatively or only weakly with
A2 cells
- B people make Anti-A but it is really anti-A1 and anti-A1 everything --> so remove anti-
everything and use anti-A1
what causes false negatives
- forgot to add reagent
- missed hemolysis
- wrong Ag:Ig
- bad technique
- improper incubation
- bad interpretation
- mixed field
*repeat and if you get same answer, think about whats added and problem solve*
what causes false positives
- bad technique
- contaminated reagents
- dirty glassware
- bad interpretation
- Rouleaux
*repeat and if you get same answer, think about whats added and problem solve*
what are the specimen related problems with red cell testing
SOLUTIONS VERIFIED GRADED A++ LATEST UPDATE
recognize ABO and Rh discrepancies and determine the general cause of the
problem ie. weak ab, weak ag, extra ab extra ag.
Normal: Forward and reverse must agree
Forward typing must be a 4+
Reverse typing must be at least a 3+
Rh should be at least a 2+
----------------------------------------
if doesn't match you have a problem
if controls are + you have a problem
decide are you missing an antigen or is it just weak --> if strong forward its probably
correct then look at the serum
are you missing an antibody or is it just week
do you have extra antibody or antigen
2. compare and contrast the major subgroups of A antigens against the usual A
antigens. Include expected serological testing results for the subgroups A2, A3
and weaker subgroups collectively. Recognize serological results which are
characteristic of subgroups.
,16. define ABO subgroup. Explain how subgroups may be detected, including a
description of any special reagents.
All group A antigens are not the same, there are A subgroups
- the A we normally think of is A1
- There is also A2, A3,.....
A1 is 80%
A2 is 20%
Doesnt leave much room for the rest, they are not common but do show up
A1 and A2 are major subgroups of blood group A. These are differentiated by the
reaction of anti-A1 lectin with A1 cells. Rarely, significance of weaker variants like A2,
A3 and Ax is important as they may cause haemolytic transfusion reactions. A2 and
A2B are rare subgroups. Individuals having these subgroups do not recognize A1
antigens as their own hence, make up specific anti A1 antibody against A1 cells.
A2 is both qualitative (composition) and quantitative (#'s)
A2 is different enough from A1 that A2's can make an anti-A1
Non-A1: 1-8%
non-A1B: 22-35%
------------------------------
how to tell A1 for Asubs
- use reagent that agglutinates only A1 cells and not others
- A1 lectin or absorbed anti-A1
Principle
,A2 and weak A subgroups can possess an anti-A1 in serum or plasma, which will react
with A1 reagent cells during reverse or serum grouping. Anti-A1 is a common cause of
ABO discrepancies in A2 and weak A subgroups.
Specimen
Red cells and serum or plasma to be evaluated.
Reagents
1. Dolichos biflorus lectin (anti-A1).
2. Group A1, A2, and O control red cells.
Interpretation
1. The lectin should strongly agglutinate A1 red cells (3+ to 4+) but should not
agglutinate A2 or O red cells. Group A red cells that fail to agglutinate with the
lectin can be considered A2 or another weak A subgroup.
2. Anti-A1 in the patient’s serum will agglutinate all A1 samples. Anti-A1 will not
agglutinate autologous, A2, or group O red cells. If the patient’s serum agglutinates
group A2 or group O red cells, another cause for unexpected reactivity should be
investigated.
If commercial lectin preparations are used, the manufacturer’s directions should be
followed for appropriate testing method and controls
A3 always gives a mixed field agglutination
What is the A1 lectin?
from plant seeds, agglutinate red cells, not an antibody but acts like one
** Dolichus biflorus **
, Anti-A1 Absorbed: agglutinates A1 cells, but reacts negatively or only weakly with
A2 cells
- B people make Anti-A but it is really anti-A1 and anti-A1 everything --> so remove anti-
everything and use anti-A1
what causes false negatives
- forgot to add reagent
- missed hemolysis
- wrong Ag:Ig
- bad technique
- improper incubation
- bad interpretation
- mixed field
*repeat and if you get same answer, think about whats added and problem solve*
what causes false positives
- bad technique
- contaminated reagents
- dirty glassware
- bad interpretation
- Rouleaux
*repeat and if you get same answer, think about whats added and problem solve*
what are the specimen related problems with red cell testing
