Page 128 - 84 human physiolofy part-1

Chapter 7

antigen is formed. These antibodies can bind to antigens on the surface of transfused red blood cells (or
other tissue cells) often leading to destruction of the cells by recruitment of other components of the
immune system. Knowledge of a individual's blood type is important to identify appropriate blood for
transfusion or tissue for organ transplantation.

Surface Antigens

Several different RBC surface antigens
stemming from one allele (or very closely linked
genes) are collectively labeled as a blood group
system (or blood group). The two most important
blood group systems were discovered during early
experiments with blood transfusion, the ABO
group in 1901 and the Rhesus group in 1937 .
These two blood groups are reflected in the
common nomenclature A positive, O negative,
etc. with letters referring to the ABO group and
positive/negative to the presence/absence of the
RhD antigen of the Rhesus group. Development
of the Coombs test in 1945 and the advent of
transfusion medicine led to discovery of more
blood groups.

Blood Group AB individuals have both A Compatibility of blood types.
and B antigens on the surface of their RBCs, and
their blood serum does not contain any antibodies against either A or B antigen. Therefore, a individual
with type AB blood can receive blood from any group (with AB being preferable), but can only donate
blood to another group AB individual.

Blood Group A individuals have the A antigen on the surface of their RBCs, and blood serum
containing IgM antibodies against the B antigen. Therefore, a group A individual can only receive
blood from individuals of groups A or O (with A being preferable), and can donate blood to individuals
of groups A or AB.

Blood Group B individuals have the B antigen on their surface of their RBCs, and blood serum
containing IgM antibodies against the A antigen. Therefore, a group B individual can only receive
blood from individuals of groups B or O (with B being preferabe), and can donate blood to individuals
of groups B or AB.

Blood group O individuals do not have either A or B antigens on the surface of their RBCs, but
their blood serum contains IgM antibodies against both A and B antigens. Therefore, a group O
individual can only receive blood from a group O individual, but they can donate blood to individuals
of any ABO blood group (ie A, B, O or AB).

Inheritance

Blood types are inherited and represent contributions from both parents. The ABO blood type is

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