An
antibody is a substance in the plasma or serum of an individual as a result of antigenic
stimulation and when mixed with the antigen reacts specifically with it in some
observable manner. The level of antibody activity depends on the immunogenicity
of the corresponding antigen.
antibody is a substance in the plasma or serum of an individual as a result of antigenic
stimulation and when mixed with the antigen reacts specifically with it in some
observable manner. The level of antibody activity depends on the immunogenicity
of the corresponding antigen.
1. Alloantibodies
Alloantibodies
are antibodies which are present in some members of a specie but not all. For example,
anti-A antibodies are present in all human being belonging to blood group B and
O. Due to the presence of alloantibodies, it is necessary to select a blood
donor who is negative for the corresponding antigen, i.e. if a recipient has
anti-A antibodies he cannot receive blood which contains A antigen.
are antibodies which are present in some members of a specie but not all. For example,
anti-A antibodies are present in all human being belonging to blood group B and
O. Due to the presence of alloantibodies, it is necessary to select a blood
donor who is negative for the corresponding antigen, i.e. if a recipient has
anti-A antibodies he cannot receive blood which contains A antigen.
Alloantibodies
to red cells are of three types:
to red cells are of three types:
a.
Natural Occurring Antibodies: It is a type of antigenic stimulation which is
unknown. It occurs in the plasma of a person who lack the corresponding antigen
and who have not been transfused or been pregnant. The most important are
anti-A and anti-B. They are usually immunoglobulin M (IgM) and read optically
at cold temperature (4oC) although reactive at 37oC are
called cold antibodies (Hoffbrand and Petit, 2006).
Natural Occurring Antibodies: It is a type of antigenic stimulation which is
unknown. It occurs in the plasma of a person who lack the corresponding antigen
and who have not been transfused or been pregnant. The most important are
anti-A and anti-B. They are usually immunoglobulin M (IgM) and read optically
at cold temperature (4oC) although reactive at 37oC are
called cold antibodies (Hoffbrand and Petit, 2006).
b.
Antibodies Resulting from Immunization: Through transfusion red cell antigens which are
absent in the recipient may be introduced and induce antibody production.
Antibodies Resulting from Immunization: Through transfusion red cell antigens which are
absent in the recipient may be introduced and induce antibody production.
c.
Antibody Produce as a Result of Exposure to Foetal
Erythrocytes:
Either through delivery these antibodies are produced. Example is development
of Rh antibodies in a Rh negative mother by a Rh positive foetus.
Antibody Produce as a Result of Exposure to Foetal
Erythrocytes:
Either through delivery these antibodies are produced. Example is development
of Rh antibodies in a Rh negative mother by a Rh positive foetus.
2.
Autoantibodies
Autoantibodies
Autoantibodies are the antibodies which are induced
by an antigen in the same individual. It also reacts with the same antigen, if
it is present in other individuals in some cases, the reaction of the antigen
and its autoantibody may not show any demonstrable clinical symptoms whereas
sometimes such a reaction may lead to haemolytic anaemia, leukaemia or
thrombocytopenia.
by an antigen in the same individual. It also reacts with the same antigen, if
it is present in other individuals in some cases, the reaction of the antigen
and its autoantibody may not show any demonstrable clinical symptoms whereas
sometimes such a reaction may lead to haemolytic anaemia, leukaemia or
thrombocytopenia.
Autoantibody are divided into two generally
categories depending on their optimum reaction temperature.
categories depending on their optimum reaction temperature.
Warm Autoantibodies: These constitute about 85% of the autoantibodies.
Their optimal reacting temperature is 37oC. Warm autoantibodies are
generally IgG in nature and can be detected with antibody test.
Their optimal reacting temperature is 37oC. Warm autoantibodies are
generally IgG in nature and can be detected with antibody test.
Cold Autoantibodies: About 15% of the autoantibodies are of this type.
They are generally IgG in nature and agglutinate red blood cell strongly at 4oC,
weakly at 24oC and not at all at 37oC. Most
autoantibodies are present in normal individuals, very few are associated with
disease.
They are generally IgG in nature and agglutinate red blood cell strongly at 4oC,
weakly at 24oC and not at all at 37oC. Most
autoantibodies are present in normal individuals, very few are associated with
disease.
