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A person with unknown blood group under ABO system has suffered much blood loss in an accident and needs immediate blood transfusion. His one friend, who has a valid certificate of his own blood type, offers for blood donation without delay. What would have been the type of blood group of the donor friend?
A
Type A
B
Type B
C
Type AB
D
Type O
Detailed Solution
Blood groups are decided by the antigens A and B on the surface of RBCs; the plasma of the recipient contains antibodies against the antigens that are absent from his own RBCs.
A transfusion is safe only if the donor's RBCs carry no antigen that the recipient's antibodies can attack.
Group O RBCs have neither antigen A nor antigen B, so they are not clumped by anti-A or anti-B antibodies of any recipient.
Therefore group O blood can be given to persons of any ABO group; O is the universal donor.
Since the recipient's group is unknown and the friend could donate without delay, the friend's blood group must be type O.
A transfusion is safe only if the donor's RBCs carry no antigen that the recipient's antibodies can attack.
Group O RBCs have neither antigen A nor antigen B, so they are not clumped by anti-A or anti-B antibodies of any recipient.
Therefore group O blood can be given to persons of any ABO group; O is the universal donor.
Since the recipient's group is unknown and the friend could donate without delay, the friend's blood group must be type O.