I Blood Group

Question 1

What is the difference in structure between I and i?

Answer 1

I is a branched chain and i is a linear chain

Question 2

The creation of the I antigen is similar to what two other blood group systems?

Answer 2

ABO and Lewis

Question 3

Describe the evolution of the I antigen from birth to adulthood.

Answer 3

Infants are very rich in i (have very little I antigen), at 18-24 months there is a shift from i to I, adults are rich in I and have very little i.

Question 4

Is anti-I more likely to be seen as an autoantibody or an alloantibody?

Answer 4

Autoantibody

Question 5

What disease is pathogenic anti-I associated with?

Answer 5

Cold agglutinin syndrome

Question 6

What disease can stimulate individuals to make a transient autoanti-I?

Answer 6

Mycoplasma pneumoniae

Question 7

Which individuals make alloanti-I?

Answer 7

Exists in most adults with adult i (very rare phenotype)

Question 8

Which disease is associated with the formation of an anti-i?

Answer 8

Infectious mononucleosis

Question 9

How often is anti-i seen in adults with the I antigen?

Answer 9

Almost never

Question 10

On what surfaces and fluids can the I antigen be detected?

Answer 10

Leukocytes, platelets, saliva, human milk, amniotic fluid, urine, ovarian cyst fluid

Question 11

In what blood type is anti-IH most commonly formed and why?

Answer 11

A1 individuals- they have the least amount of H substance and therefore would make an antibody against it

Question 12

Which blood type will anti-IH agglutinate best and why?

Answer 12

Type O because it has the highest amount of H (all red cells will have I antigen) and both I and H need to be present for the antibody to react

Question 13

With which diseases is an increased amount of i antigen associated?

Answer 13

Those with shortened marrow maturation: acute leukemia, hypoplastic anemia, sickle cell anemia, thalassemia

Question 14

At what temperature does anti-I react best?

Answer 14

4C - Cold Temperatures

Question 15

Is anti-I an IgM or IgG antibody?

Answer 15

IgM

Question 16

Does anti-I cause HTR or HDFN?

Answer 16

No - Cold reacting, IgM can’t cross placenta, fetal cells only express i antigen

Question 17

How will autoanti-I react with adult RBCs? Cord RBCs?

Answer 17

Adult - strong (lots of I antigen)
Cord - weak or not at all (mostly i antigen)

Question 18

What blood type would anti-IH react most strongly with?

Answer 18

Type O (lots of I and H antigen on surface)

Question 19

What blood type would anti-IH react weakest with?

Answer 19

A1 or A1B - These blood types have minimal levels of H antigen present as most of the H antigen is converted to A antigen.