The INDIVIDUALIST

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Serology

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Description

Flocculation is one of the basic serologic reactions, along with agglutination, hemagglutination and precipitation.

A flocculation test is characterized by a flocculent precipitate of antigen and antibody. It is typically produced through a technique called immuno-diffusion.

Flocculation refers to a process where a solute comes out of solution in the form of floc or "flakes." The term is also used to refer to the process by which fine particulates are caused to clump together into floc. The floc may then float to the top of the liquid, settle to the bottom of the liquid, or can be readily filtered from the liquid.

A precipitation reaction occurs as a result of the combination of antibodies in solution with soluble substances with which the antibodies react. If such a precipitation reaction occurs in vivo in the joints or the kidney, inflammation results because the immune complexes are filtered out in those areas, causing irritation.

In a serum precipitin test, dilutions of antigen and antibody in aqueous solution are combined until a precipitation reaction occurs and visible particles accumulate. The amount of "flocculation" can be measured by an instrument designed to measure the light scattering properties of particulate aggregations (nephelometer).

Discussion

The terms flocculant and coagulant are sometimes used interchangably, but it is more accurate to use the term coagulant for a chemical that contributes to molecular aggregation. Usually dissolved substances are aggregated into microscopic particles by a coagulant and then these particles may be flocculated into a macroscopic floc with a flocculant. In general, coagulants will have higher net charge and a lower molecular weight than flocculants.

Immunoprecipitation, referred also as "IP" is the technique of precipitating an antigen out of solution using an antibody specific to that antigen. This process can be used to identify protein complexes present in cell extracts by targeting any one of the proteins believed to be in the complex.

The Wassermann test is a complement-fixation antibody test for syphilis, named after the bacteriologist August von Wassermann.The antibody test was developed by Wassermann and Albert Neisser at the Robert Koch Institute for Infectious Diseases in 1906. The test was a growth from the work of Bordet and Gengou on complementing-fixation reaction, published in 1901, and the positive reaction is sometimes called the Bordet-Gengou-Wassermann reaction or Bordet-Wassermann reaction.

Immunoelectrophoresis (IEP) is a procedure combining separation of antigens by zone electrophoresis with diffusion of precipitating antibodies at right angles to the direction of antigen migration. The extent of migration of any protein during electrophoresis is dependent upon the electrophoresis buffer, time, voltage, and the isoelectric point of the protein. Particularly, pH determines the separation of one protein species from another. The net difference between the isoelectric point of a given protein and the pH of the electrophoresis buffer determines the extent of migration toward the cathode or the anode.

This immunological method is used to detect abnormalities in specific serum proteins and to identify specific immunoglobulins using anti-human antibody reagents. The anti-human antibody reagents have been prepared against purified fractions of human globulins and are commercially available for research or biomedical purposes.

References

INFLUENCE OF CHARACTER OF ANTIBODY UPON VELOCITY OF FLOCCULATION

William C. Boyd Ph.D.

The Journal of Experimental Medicine, Vol 74, 369-386, Copyright, 1941, by The Rockefeller Institute for Medical Research New York

From Evans Memorial, Massachusetts Memorial Hospitals, and Boston University School of Medicine, Boston

Results of a thorough study of the rates of flocculation of 20 antisera when mixed with their antigens in all proportions are presented. The relation between the alpha (constant antibody) and � (constant antigen) optima is discussed. It is suggested that most of the antisera examined can be classified into two main types, one of which, the H type, gives an optimum by both the alpha and � procedures, whereas the R type gives an optimum only by the former technique. It appears that these differences can only be accounted for by the influence of differences in the physical and chemical properties of the various antibodies. Submitted on June 18, 1941

References

THE ESSENTIAL DIFFERENCE BETWEEN THE TWO OPTIMUM PROPORTIONS FLOCCULATION RATIOS

The Journal of Experimental Medicine, Vol 80, 289-298, Copyright, 1944, by The Rockefeller Institute for Medical Research New York

William C. Boyd Ph.D. and Marjorie A. Purnell

From Boston University School of Medicine, and Evans Memorial, Massachusetts Memorial Hospitals, Boston

The fact that the optimum proportion flocculation ratio is different when determined by the alpha (Dean and Webb) and � (Ramon) procedures is pointed out. It is demonstrated that this difference is a consequence of the difference in the two methods, and that the two optima, though they may in certain cases lie near together, can never coincide. A new ratio (the epsi ratio), intermediate between the alpha and � ratios, and having theoretical advantages over both of them, is defined.

Attribution

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