Ch. 19 Lecture E
Antigens on erythrocytes
(genetically determined carbohydrate chains) give rise to different blood groups
Antibodies used:
>Anti-A antibodies bind & agglutinate A antigens >Anti-B antibodies bind & agglutinate B antigens >Anti-Rh (Anti-D) antibodies bind & agglutinate Rh antigens
Blood Typing
>Blood sample is treated with three different antibodies >agglutination indicates that antigen is present on erythrocytes >no agglutination indicates that specific antigen is absent
Universal donor: Blood type O-
>Erythrocytes do not have A, B, nor Rh surface antigens >Can be given to any other blood type in an emergency when blood matching is not an option
Universal recipient: Blood type AB+
>These individuals do not make antibodies to A, B, or Rh antigens >Individuals with AB+ blood type can generally receive blood from any blood type donors
Agglutination
>antibody molecule binding to antigens & stick them together. >causes clumping of red blood cells.
Antibodies (called agglutinins)
>bind to surface-bound antigens >cause them to clump together or agglutinate
Blood transfusions
>blood taken from a donor is given to a recipient >commonly used treatment procedure in today's medicine, but was not always the case...
Transfusion reaction
>recipient antibodies bind to donor antigens >causes agglutination that destroys donor erythrocytes, possibly leading to *kidney failure* & *death*
blood matching (transfusion)
Antigens and antibodies are basis for _________________ >blood taken from a donor is screened for compatibility prior to its administration to a recipient
antibodies
Blood typing in laboratory uses _________ that bind to individual antigens on erythrocytes
Rh blood group
Features Rh antigen >first discovered in rhesus monkeys
foreign antigens
Immune system does produce antibodies to ___________ >means that antibodies are present in your plasma only if antigens are absent from your erythrocytes
Rh antigen (D antigen)
Individuals with _________ on their erythrocytes are Rh-positive (Rh+) & those without D antigen are Rh-negative (Rh-)
Blood Type O
Neither A nor B antigens are present on erythrocytes >there is no O antigen >O denotes absence of A & B antigens only
Blood Transfusions
Note that anti-A and anti-B antibodies are *pre-formed* >they are present in plasma even if individual has never been exposed to those antigens
Hemolytic Disease of Newborn
Rh antibodies attack fetal blood causing severe anemia & toxic brain syndrome
Anti-Rh antibodies
are produced only if a person has been exposed to blood containing Rh antigens >Therefore, an Rh- individual generally has no anti-Rh antibodies unless he or she has been exposed (sensitized) to Rh+ erythrocytes
Blood Type AB
both A & B antigens are present on erythrocytes
ABO and Rh blood groups
combined give rise to eight common blood types >*Type O+ is most common* blood type in U.S. >*Type AB- is least common*
Discovery of surface markers or antigens (agglutinogens)
found on most biological molecules & all cells, including erythrocytes, lead to development of safer transfusion practices
Blood Transfusion: Matching
is still the *safest practice*
A match
occurs if donor blood type is compatible with recipient blood type
Blood Type A
only A antigen is present on erythrocytes
Blood Type B
only B antigen is present on erythrocytes
Immune system
recognizes foreign antigens & responds by trying to remove them
Immune response
was responsible for many fatalities in early-era transfusion patients
hemolysis
Ultimately, agglutination promotes erythrocyte destruction called __________
"self " antigens
Your immune system recognizes antigens on your erythrocytes as _________ >does not produce antibodies to self antigens, because if it did, your antibodies would bind your own antigens
ABO blood group
__________ features two antigens, A & B antigens & gives rise to 4 ABO types: >Type A >Type B >Type AB >Type O
Two groups
____________ of the 30 different antigens found on erythrocytes are particularly useful for clinical use: *ABO blood group & Rh blood group*