Q1ii: The physiological reasons making it safe to give O negative blood to patients
Importance
- RBC transfusion is the transfer of PRBC to ↑ of RBC & ∴the O2 carrying capacity of blood
- Multiple inherited Ag’s are displayed on RBC surface
- ~30 different blood groups, but 2 most important which can cause life threatening reactions are ABO & Rh → these groups refer to Blood Type
ABO System
- Carbhohydrate chain AG’s on surface of RBC
- Also present on many other cell surfaces (salivary glands, kidney, liver, lungs)
- Individuals develop IgM AB’s to the AG’s NOT on their RBCs (due to early exposure to food & bacteria)
Group
O
Ag
None
Ab
Anti A & Anti B
Donor
Universal
A
A
Anti B
Only to A
B
B
Anti A
Only to B
AB
A & B
None
Only to AB
Rhesus System
- AG’s displayed on RBC (none other cells)
- D is the most important because most antigenic
Group
Rh (+)
Rh (D) Ag
Present
Ab
Nil
Donor
To Rh (D) +
Rh (-)
Absent
On exposure to Rh D (+) blood, develops anti-D
To Rh (D) + or –
- Do not naturally develop Ab (like ABO)
- Only on exposure i.e. Rh (-) mother exposed to Rh (+) foetus
- Will then develop IgM, then IgG Ab’s
- If the next child is Rh(+) this will cause haemolytic reaction due to Abs
O Negative Blood
- Contains no A, B, or Rh(D) Ags to react with recipient Abs
- ∴safe to give to all blood groups