Lecture 11 Flashcards Preview

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1

Antibodies in plasma or serum
group A

has anti-B

2

Antibodies in plasma or serum
group B

has anti-A

3

Antibodies in plasma or serum
group AB

has neither

4

Antibodies in plasma or serum
group O

has anti-A and anti-B

5

Looking for presence or absence of antigens on the surface of RBCs
group A

has A antigen 40% of population

6

antigens on the surface of RBCs
group B

has B antigen 11%

7

antigens on the surface of RBCs
group C

has A and B 4 %

8

antigens on the surface of RBCs
group O

has neither A nor B 45 % (most common)

9

Blood Grouping
sample:

EDTA (lavender, pink )or red top; do not separate, refrigerate

10

• direct or forward grouping looking for antigen on the surface

1 drop RBCs + 1 drop anti-A or anti-B

11

• reverse or indirect grouping when looking for the antibody :

patient serum with commercial A or B cells(test for blood group antibodies)

12

Other than the ABO and Rh blood group systems

some 20 blood group systems, such as Duffy, Kidd and Kell, on human red cells.

13

Antigens on surface of RBCs – D is acquired not naturally in the body
Rh D+

has D antigen 85 % of population

14

Antigens on surface of RBCs – D is acquired not naturally in the body
Rh D-

lack D antigen

15

Antigens on surface of RBCs – D is acquired not naturally in the body
Rh Du

weak Rx but is D+ rare

16

Antibodies: IgG type, occur after exposure to antigens
Rh D+

lacks anti-D

17

Antibodies: IgG type, occur after exposure to antigens
Rh D-

anti-D if exposed to D Ag by transfusion or pregnancy

18

Rh Typing

Patient RBCs + anti-D, heated on slide box to encourage agglutination by IgG

19

Gel (solid Phase) Testing for Blood Group

• Card is pre –filled with gel and mixed with appropriate reagent
• Diluents of patients’ cells pipette on to gel and card incubated
• Card centrifuged and red
• Agglutination stays on top of gel
• No agglutination goes to the bottom

Look at slide
agglutination ring on top and no agglutination at the bottom

20

A genotype:

the genes inherited from each parent’s blood group which are present on the chromosomes.

21

A phenotype:

the observable effect of the inherited genes: that is, the blood group itself.

22

The A and B genes

are dominant over the O gene and the phenotype A
can therefore arise from either the AO or the AA genotype.
Similarly, the phenotype B can arise from either the BO or the BB genotype.
look at slide for geno and phenotype

23

Haemolytic Disease of the Newborn (HDN):

 when mother is Rh (–) and fetus is Rh (+); fetal cells enter maternal circulation during delivery
 mother develops anti-D (IgG) which destroys fetal RBCs in subsequent pregnancies
 mother given injection of RhD immunoglobulin (RhoGAM, RhIG) within 72 hrs of delivery to neutralize RhD antigens on fetal cells

24

Cross Match (Blood Compatability Testing)
Specimen:

Pink, lavender or red top; do not separate strict adherence to patient identification protocols

25

Cross Match (Blood Compatability Testing)
Procedure:

1. Both donor and recipient are ABO and Rh typed
2. Antibody Screen: recipient serum tested against a panel of cells for antibodies other than ABO
3. Recipient serum tested for reaction to donor cells

look at slide

26

Prenatal Screen
Specimen Sample

Specimen: red top or EDTA
Procedure: ABO and Rh typing Antibody Screen

27

Indirect Antiglobulin Test (IAT); Indirect Coombs Test; Antibody Screen

specimen and sample

Specimen: serum or EDTA
Procedure: patient serum is tested for antibodies to blood groups other than ABO; performed as part of cross match and as part of prenatal screen

28

Direct Antiglobulin Test (DAT) Direct Coombs Test
specimen and sample

Specimen: red top or EDTA (need RBC’s)
Procedure: patient cells are tested for presence of bound antibodies

29

Major cross match: for coombs test

recipient serum, donor cells,

30

Minor cross match for coombs test

recipient cells, donor serum