Blood Type (ABO)

The Function of Antibodies• Our bodies make antibodies to protect us from

“foreign” molecular species.

• Persons with A-antigens produce B-antibodies (Anti-B) but not A-antibodies (Anti-A) since A-antigens are natural in their system.

The Function of Antibodies• Likewise, persons with B-antigens produce A-

antibodies (Anti-A) but not B-antibodies (Anti-B) since B-antigens are natural in their system.

The Function of Antibodies• Persons with A-antigens and B-antigens do not

produce A-antibodies (Anti-A) nor B-antibodies (Anti-B) since both occur naturally in their system.

Agglutination• The clumping process that takes place when

RBCs containing a particular antigen (A or B) are mixed with serum containing the antibody specific for that antigen.

• The serum containing the antibody is called antiserum.

Agglutination

Blood Types and Serum Antibodies

Blood Type

Antigens on RBC

Antibodies in Serum

A A Anti-B

B B Anti-A

AB AB Neither anti-A or anti-B

O Neither A nor B

Both anti-A and anti-B

Blood Group Distribution in the United States

• 43% O• 42% A• 12% B• 3% AB

Other RBC Antigens• There are more than 15 known RBC antigens

systems.

• The A-B-O system is commonly used in blood typing.

• The Rh system is also used for blood types.

The Rh System• Based on the Rh factor or D antigen.

• A person whose RBCs have the D antigen is said to be Rh positive.

• Likewise, a person whose RBCs do not have the D antigen is said to be Rh negative.

Blood Type Distribution in the United States

Identification of Blood with Known Antiserum

Anti-A Serum +

Whole Blood

Anti-B Serum +

Whole Blood

Antigen Present

Blood Type

+ - A A- + B B+ + A and B AB- - Neither

A nor BO

+ shows agglutination; - shows absence of agglutination.

Identification of Blood with Known Cells

A Cells +

Blood

B Cells +

Blood

Antibody Present Blood Type

+ - Anti-A B- + Anti-B A+ + Anti-A and Anti-B O- - Neither Anti-A

nor Anti-BAB

+ shows agglutination; - shows absence of agglutination.

Antiserum A, B, and Rh are Added to a Blood Sample

• No agglutination is occurring.

Antiserum A is Added to an A or AB type Blood Sample

Antiserum B is Added to aB or AB type Blood Sample

Antiserum Rh is Added to a Rh positive Blood Sample

Name that Blood Type

Name that Blood Type