Comprehensive ABO Blood Group and Transfusion Reaction Overview

What complications are associated with transfusion of incompatible blood?

Acute intravascular hemolysis, renal failure, death

What is associated with the transfusion of incompatible organs?

Acute humoral rejection

On which chromosome is the ABO gene located?

Chromosome 9

What are the four ABO phenotypes?

A, B, AB, O

What are the possible ABO genotypes?

AA, AO, BB, BO, AB, OO

Which ABO gene is amorphic?

O gene

What structure carries ABO and H antigens on RBC membranes?

Glycoproteins

Where can ABO antigens be found?

RBCs, platelets, lymphocytes, epithelial cells, endothelial cells, heart, lungs, bowel, pancreas, kidneys

When do ABO antigens appear in the embryo?

5-6 weeks gestation

At what age do adult levels of ABO antigens appear?

2-4 years old

When do ABO antibodies begin to develop?

3-6 months of age (peak 5-10 years)

Are ABO antibodies present at birth?

No

Are ABO antibodies naturally occurring?

Yes

What do anti-A and anti-B antibodies target?

Antigens the individual lacks on their RBCs

What immunoglobulin class are anti-A and anti-B antibodies?

Predominantly IgM

What immunoglobulin class is anti-O?

IgG

Can ABO antibodies activate complement?

Yes

What antibodies do group O individuals produce?

Anti-A, Anti-B, Anti-A,B

Which antibody may be found in subgroup A individuals?

Anti-A1

At what temperature do ABO antibodies react best?

Cold / room temperature

What antibody is a cross-reacting IgG antibody not a combination of anti-A and anti-B?

Anti-A,B

What type of chains are ABO antigens built on?

Type 1 and Type 2 oligosaccharide chains

What three genes modify ABO chains and where are they located?

H (FUT1) chromosome 19; Se (FUT2) chromosome 19; ABO chromosome 9

What enzyme do H, Se, and ABO genes produce?

Glycosyltransferase

What are the sugars added by glycosyltransferases called?

Immunodominant sugars

What are the immunodominant sugars for H, A, and B antigens?

H: L-fucose; A: N-acetyl-D-galactosamine; B: D-galactose

What antigen is the platform for A and B antigens?

H antigen

What immunodominant sugar encodes the H antigen?

L-fucose

What blood group results from the FUT1 gene?

H

Which blood group has the highest concentration of H antigen?

O

Which blood group has the least H antigen?

AB

What chains are ABH antigens constructed on?

Type 1 and Type 2 chains

What is the Bombay phenotype?

hh and sese genotype (Oh); absence of H, A, and B antigens

What is the inheritance pattern of Bombay phenotype?

Autosomal recessive

How does Para-Bombay differ from Bombay?

hh with at least one Se gene; weak A/B from plasma absorption

How is Bombay phenotype detected?

Reacts with O blood; anti-A, anti-B, anti-A,B, anti-H present

Which genotypes are secretors?

SeSe or Sese

Which gene determines secretor status?

FUT2

Which antigens absorb onto platelets and lymphocytes but not granulocytes or monocytes?

A, B, and H

How is protection decreased in non-secretors?

Lack of soluble antigens in body fluids

What conditions are non-secretors more prone to?

Infections, celiac disease, asthma, autoimmune disease, heart disease, diabetes, UTIs, yeast infections

What are the two components of routine ABO typing?

Forward and reverse typing

What does forward typing test?

Patient RBCs with anti-A and anti-B

What does reverse typing test?

Patient plasma with A1 and B cells

Which ABO subgroups are more common?

A subgroups (A1 most common)

Which subgroup shows stronger anti-H reactivity, A1 or A2?

A1

What characteristics define ABO subgroups?

Decreased antigen sites, weak reactions, variable anti-H

What is used to distinguish A1 from A2?

Lectins

Which lectin binds A1 cells?

Dolichos biflorus

Which lectin binds H antigen and O cells?

Ulex europaeus

Which lectin binds B antigen?

Bandeiraea simplicifolia

Which lectin binds N antigen?

Vicia graminea

Which lectin binds M antigen?

Iberis amara

What immunoglobulin are ABO antibodies mainly?

IgM

What immunoglobulin are Rh antibodies mainly?

IgG

Which test for fetal-maternal hemorrhage is qualitative?

Rosette test

Which test for fetal-maternal hemorrhage is quantitative?

Kleihauer-Betke test

What happens if the Rosette test is negative?

Standard Rhogam dose is sufficient

What happens if the Rosette test is positive?

Run Kleihauer-Betke test

Who shows stronger ABO typing reactions?

Healthy individuals

Who shows weaker ABO typing reactions?

Elderly individuals

What is the source of naturally occurring ABO antibodies?

Gut bacteria (Enterobacteriaceae)