The utility of antiglobulin testing in blood group serology

Term Paper 2013 10 Pages

Biology - Human Biology


Table of contents


The Antiglobulin Test Systems
Liquid phase systems
Column agglutination systems
Solid Phase

The antiglobulin techniques and types
The direct antiglobulin test
The indirect antiglobulin test

The Use of antiglobulin testing and reagents
Blood Grouping
Utility of Antiglobulin Testing
Detection of haemolytic disease of the Newborn/foetus (HDN/F)
Utility of Antiglobulin test
Identification and screening of blood group system antigens/antibodies, Research and Education
Utility of antiglobulin testing
Detection and identification of transfusion reactions
Utility of antiglobulin Testing

Other uses of antiglobulin testing other than blood group serology


The Utility of the Direct and Indirect Agglutination in blood group serology


The detection of reactions between antigen and antibody has been used to “phenotype” cells and to establish the presence of either antibody or antigen. Blood group antigens are either IgG or IgM. Though divalent, the IgG molecule is monomeric and the distance between two Fab regions is not generally enough to allow for direct agglutination. This therefore means that the detection of IgG reactions will have to be enhanced.

The most commonly employed techniques include the use of enzymes to cleave negatively charged particles on the surface of the red blood cells in order to reduce the negative charge and hence repulsion of the red cells. This then reduces the distance between cells and enables them to come together whence an agglutination reaction can be observed. Secondary antibodies may also be used to help in the detection of the reaction.

Apart from blood group serology, the detection of other human proteins which are capable of developing IgG antibodies and fixing complement can utilize this technique. Disease therapy monitoring in immunoglobulin therapies may also employ this technique.

The Antiglobulin Test Systems

Test systems that have been used in the detection of serological reactions can be classified into three broad categories namely

Liquid phase systems

This is the gold standard for detection of serologically significant reactions. The detection of reaction is by use of tubes or microtitre wells to visualize the reaction. There need be meticulous attention to the reactions and especially when the indirect antiglobulin test is performed and at the washing stage in particular.

Column agglutination systems

This simple column test allow for the use of glass beads or a gel system in six columns. The gel or microbead system is formulated to allow the passage of unagglutinated cells to the bottom but not agglutinated cells. A positive reaction is thus characterised by agglutinates at the top of the column and a button of free red cells at the bottom. Reagent IgM or Antiglobulin can thus be added to type the reaction without need for washing.

Solid Phase

In the solid phase system, a monolayer of cells on the plate surface signifies a positive reaction while a discrete button of cells is negative. The solid phase systems require accurate and standardized centrifugation steps. The solid phase techniques are thus very well adaptable to automated systems.

The use of Antiglobulin techniques first described by Carlo Moreschi in 1908 and rediscovered in 1945 by Robin Coombs, Rob Race, and Arthur Mourant, allowed the identification of many other blood group antigens in the decades that followed(Michael & Derwood 2009).

The antiglobulin techniques and types

Today, three types of antiglobulin types are available in the market. These are either polyclonal or monoclonal. The use of polyclonal test sera is however not in common use. The antiglobulins available include;

a. Anti-IgG antiglobulin this contains only anti IgG antibodies
b. Anti-Complement C3d or C4d. These reagents contain only the monoclonal antibodies against complement which are used especially to detect complement activity without the undue influence of complement fixing antibodies
c. Anti-IgG + anti-Complement. This is a blend which is used when the detection of complement fixing is desirable(Beck 2009).

There are two types of antiglobulin testing, the direct and the indirect antiglobulin tests.

The direct antiglobulin test

The direct test is used to detect the antibodies that have reacted with the patient red cells in vivo. These maybe found coating red cells and may be associated with alloantibodies coating red cells in Haemolytic disease of the Newborn or autoantibodies in autoimmune haemolytic anaemia.



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Title: The utility of antiglobulin testing in blood group serology