Cold Antibodies in Blood Group Systems

Questions and Answers

What class of immunoglobulins are cold antibodies usually?

IgM

At what temperature do cold antibodies react optimally?

4°C

What are the most important cold antibodies in terms of blood transfusion?

anti-A and anti-B

What other blood group systems, besides ABO, can have cold antibodies?

Hh, Ii, Lewis, MN, and P Signup and view all the answers

Why are they called cold antibodies despite reacting at 37°C?

Historical reason, as they were first discovered to react at low temperatures Signup and view all the answers

Which class of immunoglobulins is capable of transplacental passage from mother to fetus?

IgG Signup and view all the answers

What is the most important immune antibody in terms of its potential to cause hemolytic disease of the newborn?

Rh Ab (anti-D) Signup and view all the answers

Why is transplacental passage of IgG antibodies significant?

It provides the fetus with protection against infections Signup and view all the answers

What is the significance of the Rh Ab (anti-D) in pregnancy?

It can cause hemolytic disease of the newborn if the mother is sensitized Signup and view all the answers

Why is it important to identify and monitor Rh-negative women during pregnancy?

To prevent maternal sensitization and potential complications in future pregnancies Signup and view all the answers

What is the terminal sugar found on the H antigen of the O blood group?

L-fucose Signup and view all the answers

What is the additional sugar found on the A antigen?

N-acetyl galactosamine (galnac) Signup and view all the answers

What is the difference between the B antigen and the H antigen?

The B antigen has an additional D-galactose (gal) compared to the H antigen. Signup and view all the answers

What is the common sugar found on the H antigen of the O blood group?

L-fucose (fuc) Signup and view all the answers

How do the A and B antigens differ from the H antigen?

The A antigen has an additional N-acetyl galactosamine (galnac) and the B antigen has an additional D-galactose (gal) compared to the H antigen. Signup and view all the answers

When both A and B genes are inherited, how do the B enzyme and A enzyme interact with the H substance?

The B enzyme competes more efficiently with the A enzyme for the H substance. Signup and view all the answers

What is the name of the enzyme associated with the A gene?

α-3-N-acetylgalactosaminyltransferase Signup and view all the answers

How do the B enzyme and A enzyme differ in their interaction with the H substance?

The B enzyme competes more efficiently for the H substance than the A enzyme. Signup and view all the answers

What is the name of the enzyme associated with the B gene?

α-3-D-galactosyltransferase Signup and view all the answers

What happens when both A and B genes are inherited in terms of enzyme interaction with the H substance?

The B enzyme outcompetes the A enzyme for the H substance. Signup and view all the answers

On an AB adult cell, how do the average number of A antigen sites compare to B antigen sites?

The average number of A antigen sites is less than B antigen sites. Signup and view all the answers

When do the ABH antigens develop in fetal life?

Early in fetal life. Signup and view all the answers

Do the ABH antigens increase in strength during the gestational period?

No, they do not increase much in strength. Signup and view all the answers

What is a characteristic of the ABH antigens in terms of their development and strength?

They develop early in fetal life and do not increase much in strength during the gestational period. Signup and view all the answers

What can be said about the strength of ABH antigens after they develop in fetal life?

They do not increase much in strength. Signup and view all the answers

Study Notes

Cold Antibodies

Cold antibodies are usually IgM and react optimally at a cold temperature of 4°C.
Despite being reactive at 37°C, they are still referred to as cold antibodies.
The most important cold antibodies are anti-A and anti-B.

Other Blood Group Systems

Other blood group systems for which antibodies exist include Hh, Ii, Lewis, MN, and P.

Transplacental Passage

Only IgG antibodies are capable of passing from mother to fetus through the placenta.

Rh Antibody (Anti-D)

The Rh antibody (anti-D) is the most important immune antibody.

ABO Blood Group Antigens

The H antigen of the O blood group has a terminal L-fucose (fuc).
The A antigen has an additional N-acetyl galactosamine (galnac).
The B antigen has an additional D-galactose (gal).

Enzyme Competition

When both A and B genes are inherited, the B enzyme (α-3-D-galactosyltransferase) competes more efficiently for the H substance than the A enzyme (α-3-N-acetylgalactosaminyltransferase).

AB Antigen Sites

On an AB adult cell, the average number of A antigen sites is less than B antigen sites.

Development of ABH Antigens

ABH antigens develop early in fetal life but do not increase much in strength during the gestational period.

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Description

This quiz covers the characteristics and types of cold antibodies, including IgM, optimal reaction temperatures, and specific blood group systems. Topics include anti-A, anti-B, Hh, Ii, Lewis, MN, and P blood groups.