ABO Blood Group

Question 1

ABO Testing

Answer 1

AB = forward A/B positive, reverse negative 
A = forward A positive, reverse B positive 
B = forward B positive, reverse A positive 
O = forward negative, reverse A/B positive

Question 2

ABO Frequencies

Answer 2

AB = 4% white and black 
A = 40% white, 27% black 
B = 11% white, 20% black 
O = 45% white, 49% black

Question 3

ABO Antibodies

Answer 3

Group A and B have IgM
Group O have IgG with some IgM
React at room temp or below in vitro
Can activate copmlement to completion at 37C
RBC immune form are predominantly IgG
Appear at 4 to 6 months, peak at 5 to 10 years, decline over 65 years

Question 4

Group O Phenotype

Answer 4

Anti-A,B antibody (inseperable)

RBC immune has both anti-A and B

Question 5

Group B/O Phenotype

Answer 5

Have both anti-A and anti-A1 antibodies
anti-A reacts with both A1 and A2 antigens
anti-A1 reacts with only A1 antigens
A2 and A2B phenotypes can make anti-A1 antibodies, cause ABO discrepancy

Question 6

Hh Genes

Answer 6

H and h alleles
H codes for a fucosyltransferase enzyme that adds fucose onto Type 2 chains on the RBC to form the H antigen
A and B antigens are built onto H antigen
h allele is a silent allele (amorph)

Question 7

Se/se Genes

Answer 7

Se allele codes for a fucosyltransferase enzyme that adds fucose onto Type 1 chains in the secretory glands
Controls expression of H antigens in secretions
see allele is amorph

Question 8

ABO Genes

Answer 8

A and B alleles code for glycosyltransferase enzymes that add a sugar onto H antigens to produce A and B antigens
O allele does not code a functional enzyme

Question 9

Type I Chain

Answer 9

In the secretions
#1 carbon of Gal is attached to # carbon of GlcNAc

Question 10

Type 2 Chain

Answer 10

On RBC membrane 
#1 carbon of Gal is attached to the #4 carbon of GlcNAc

Question 11

A Antigen

Answer 11

1 carbon of GalNAc is attached to #3 carbon of Gal

Question 12

B Antigen

Answer 12

1 carbon of Gal is attached to #3 carbon of Gal

Question 13

Bombay (Oh) Phenotype

Answer 13

Homozygous inheritance of h/h and se/se
Results in inability to form the H antigens and ABO antigens on the RBC and in secretions
Make clinically significant anti-H

Question 14

Para-Bombay Phenotype

Answer 14

Homozygous h/h with Se/__
Red cells lack the H antigen but have small amounts of AB antigen
Express type I chain ABH antigens in their secretions and plasma
Antigens can passively absorb onto the RBC, results in weak A and B expression
Make clinically significant anti-H

Question 15

Secretions

Answer 15

Plasma, saliva, synovial fluid, seminal fluid, bile

Question 16

Blood Group Substance: Soluble Antigen

Answer 16

Antigens found in secretions that are not bound to a membrane such as RBC or epithelial cells
Controlled by Se gene

Question 17

ABO Subgroups

Answer 17

A1: nothing unexpected
A2: 2+ anti-H, 0/2+ A1 cells
A3: 2+ MF anti-A, 2+ MF anti-AB, 3+ anti-H, 0/2+ A1 cells
Ax: 0/+ anti-A, 1-2+ anti-AB, 4+ anti-H, 0/2+ A1 cells