ICT

Anti Human Globulin Test (Coomb’s Test)

Coomb’s test or Anti Human Globulin test is very useful in recognized weak immunologic reactions. It is widely used in the identification of Du, Compatibility testing, Antibody screening and identification of Sensitized red cells. Anti Human Globulin is made by injecting human globulin in rabbit and purifying the Anti human globulin (AHG) produced by the rabbit. It is commercially available. There are two types of Coomb’s test : Direct Coomb’s Test (DCT) or Direct Anti Human Globulin Test (DAT) Indirect Coomb’s Test (ICT) or Indirect Anti Human Globulin Test (IAT) Direct Coomb’s Test (DCT) or Direct Anti Human Globulin Test (DAT) Direct Coomb’s Test (DCT) or Direct Anti Human Globulin Test (DAT) is performed to detect anti-D antibody or other antibodies attached to the Red Blood Cell surface with in the blood stream. This occurs in the following circumstances : When there is a ‘Rh’ Positive baby in the womb Read More

ICT

Blood Group and Pregnancy

‘ABO’ Blood Grouping & Pregnancy :             If Group-A blood is given (in error) to a group-B, a foreign substance (A antigen) is introduced into the blood stream of an individual who already has natural antibody (anti-A), which will reacts with the antigen on the incoming blood cells and cause them to agglutinate. This leads to serious problems such as blocking of blood vessels as the incoming blood cells are agglutinated. This is forward by haemolysis of these cells as complement links to the antigen-antibody reaction.             The large number of incoming antigenic cells started an immune reaction leading to the production of Immune Antibody. These antibodies are IgG in nature. Which readily pass through the placenta and may therefore leads to mother-foetus ‘ABO’ incompatibility problem. This is particularly serious if the mother is ‘O’ type and the foetus type ‘A’, ‘B’ or ‘AB’.             Immunization also occurs due to Read More

ICT

Rhesus Blood Group System & It’s Variant

In 1940 Landsteiner and Wiener reported that when the red cells of Macacus Rhesus monkeys were introduce into rabbits and guinea pigs, antibodies were evoked. These caused clumping not only of monkey’s red blood cells but also of the red blood cells of about 85% of human beings. The antigenic factor present on the surface of the human red blood cells called ‘Rh’ antigen. ‘Rh’ Blood group system is the second most important blood group system in human. ‘Rh’ Positive blood cells are antigenic for ‘Rh’ Negative individuals. Introduction of ‘Rh’ Positive cells (antigen) into an ‘Rh’ negative individual will stimulate the production of antibodies (anti-D) which will agglutinate and haemolysed ‘Rh’ Positive cells in 60 -70 cases. ‘Rh’ antibodies are not occurring naturally but develop only after exposure of an individual to antigen which the individuals lacks and the resultant antibody (IgG in nature), is called an immune antibody. Read More

ICT

ABO Blood Group System & It’s Determination

The Human ‘ABO’ Blood Group System discovered by Landsteiner’s in 1901. The principle of Blood grouping is based on the Landsteiner’s Law. Landsteiner’s Law : “The corresponding antibody is never present in the serum of an individual when the antigen is manifest on his red cells”. (Same type of antigen and antibody cannot stay together in an individual). ‘ABO’ Blood group system is divided into four major groups and they are ‘A’ group, ‘B’ group, ‘AB’ group and ‘O’ group. This depends on the presence of ‘A’ antigen or/and ‘B’ antigen on the surface of the Red Blood Corpuscles (RBCs) and determined by agglutination reactions obtained by mixing their Red blood cells with two different reagents (corresponding antibodies), known as Anti-A and Anti-B. The percentage of different group in Indian and Caucasian (US) population as approximately as follows : ‘ABO’ Group is determined by two methods : Forward Grouping Reverse Read More