Lecture 5: Blood groups Flashcards
RBC membranes have _____________ on their external surfaces
glycoprotein antigens
These antigens are:
Unique to the individual
Recognized as foreign if transfused into another individual
Promoters of agglutination and are referred to as agglutinogens
used to classify blood groups
Presence or absence of these antigens
Humans have ____ varieties of naturally occurring RBC antigens
30
cause vigorous transfusion reactions when they are improperly transfused
The antigens of the ABO and Rh blood groups
https://www.youtube.com/watch?v=L06TJTMVkBo
The ABO blood groups consists of:
Two antigens (A and B) on the surface of the RBCs
Two antibodies in the plasma (anti-A and anti-B)
________ (ANTIGENS) and their corresponding antibodies cannot be mixed without serious ___________
Agglutinogens
hemolytic reactions
2 kinds of antibodies
= anti-A and anti-B
2 kinds of antibodies = anti-A and anti-B
> Thus 4 possibilities in the plasma as well
- alpha, beta
- Alpha and beta
- O
Alpha antibody interacts (agglutinates) with the A antigen
Beta-antibody agglutinates with the B antigen
People with antigen A in their RBCs always have B-antibody in
their plasma
They cannot have alpha-antibody because this will agglutinate
with their own RBC and destroy them
Individuals with antigen B
have alpha-antibody
If a patients is given the wrong blood type
- antibodies in patients own plasma react with antigens of donor
- Clumping of donor blood – death
Remember: it is the plasma antibodies of the recipient that react with the antigens (RBCs) of the donor - Group 0 can donate blood to anyone
- Group 0 can receive only 0 blood
Rh Blood groups
- Rh agglutinogens are in SOME blood
- Presence of the Rh agglutinogens on RBCs is indicated as Rh+
- Anti-Rh+ antibodies are not spontaneously formed in Rh–
individuals - However, if an Rh– individual receives Rh+ blood, anti-Rh antibodies
form - A second exposure to Rh+ blood will result in a typical transfusion
reaction
Rh Blood groups and birth
- Rh- mother bears Rh+ positive child conceived from positive
father - At birth some of the child’s RBCs pass through plasenta into
mother’s circulation - Rh antigens promote formation of Rh antibodies in maternal blood
- First child = normal
- Future pregnancies cause haemolytic disease of newborn or
erythorblastosis foetalis - Rh antibody concentration rise in blood of mother shortly after birth
of Rh-positive baby = need to desensitize mother
Transfusion reactions
- RBC antigens encounter their antibodies
- Binding
- This coating of antibody have several effects:
> Make cell adhere to each other (agglutinate)
> Activate the compliment system - break open (lyses) the cell =
release haemoglobin and potassium (affects nerve and muscle
function)
> Expose the cell for attack by macrophages (reduced blood
pressure; overall shock)
> Life threatening
How is the CBC test used?
The complete blood count (CBC) is often used as a broad screening test to determine your general health status. A CBC may be used to:
Screen for a wide range of conditions and diseases
Help diagnose various diseases and conditions, such asanemia,infection,inflammation,bleeding disorderorleukemia, to name just a few
Monitor the status of a disease or condition and the effectiveness of treatment after a diagnosis is established
Monitor treatment that is known to adversely affect blood cells, such aschemotherapyor radiation therapy
What diseases can be detected with a CBC?
A CBC can help detect a number of conditions. Some examples include:
Anemiaof various etiologies
Autoimmune disorders
Bone marrow disorders
Dehydration
Inflammation
Hemoglobin abnormalities
Leukemia
Low platelets
Lymphoma
Myeloproliferative neoplasms
Myelodysplastic syndrome
Sickle cell disease
Thalassemia
What does an elevated RDW mean?
An increased variation in red blood cell size, a condition known asanisocytosis.
