HETEROPHILE ANTIBODY

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SERO-IMMUNOLOGICAL REACTIONS

AND BASIC PRINCIPLE

HETEROPHILE ANTIBODY

In the serum of patient suffering from the presumably infectious disease, infectious mononucleosis, Paul and Bunnell discovered strong agglutinin for sheep erythrocytes called heterophile antibodies.  Three types of heterophile antibodies are infectious mononucleosis, Forssman and serum sickness.  Heterophile antibodies have an affinity for related or identical antigens found in sheep cells, guinea pig tissue and many other unrelated biological substances.  These antibodies are present in the sera of 90 % of cases, and this characteristic provides the basis for the test.

Infectious mononucleosis, otherwise known as glandular disease, acute benign lymphoblastosis, acute lymphadenosis, lymphocytic angina, and "kissing disease," is more commonly found in young people.  Experimental transmission of the disease in animal supports the possibility of a viral agent -- Epstein-Barr Virus (EBV).  It is transmitted with difficulty and only by intimate oral contact.  It is characterized by fever, generalized lymph node enlargement, and lymphocytosis with atypical lymphocytes.

It is possible to detect heterophile antibodies in the blood of individuals who do not have infectious mononucleosis.  They may be produced by the injection of biologicals containing serum, particularly in individuals who manifest serum sickness following these injections.  Moreover, they maybe present naturally in low titer as Forssman antibodies.  The latter is referred to as native heterophile.

The Rapid Plate screening test is valuable for screening infectious mononucleosis.  In many laboratories, serodiagnostic methods are used in the determination of heterophile antibodies, namely:

1. Davidsohn's Presumptive Heterophile Test


2. Davidsohn's Differential Test

The presumptive test is used to demonstrate the titer of the total heterophile antibody content.  Serial dilutions are made and if a patient has a titer of more than 1:224 or between 1:56 or 1:112, the differential test is carried out.  The differential heterophile test is used to confirm the presumptive test and to differentiate between between the three heterophile antibodies which may have caused the increased titer in the presumptive test.  It involves two procedures -- absorption and titration.  Antigen prepared from guinea pig kidney will absorb the Forssman and serum sickness antibodies.  Absorption of antibody, after exposure to either antigen, is indicated by the loss of serum's ability to agglutinate sheep erythrocytes.  A comparison of the titer obtained in the presumptive test, with titers obtained after absorption, will reveal the type of antibodies which caused an increase in the presumptive test.

Indications for performing the differential heterophile test are as follows:

1. A titer of antisheep cell agglutinins of 1:112 or less, as determined by the presumptive test, in cases of infectious mononucleosis.


2. A titer of antisheep cell agglutinins of 1:56 or higher in patients who demonstrate in clinical or hematologic findings compatible with infectious mononucleosis.


3. A history of recent horse serum injection in patients who demonstrate an antisheep agglutinins titer of 1:56 or higher.

Interpretation of differential test results - Patient's serum positive for infectious mononucleosis

1. Titer in heterophile test - 1:56 or higher


2. Absorption with boiled guinea pig kidney antigen - antisheep agglutinins remain.


3. Absorption with boiled beef cell antigen - antisheep cell agglutinins are absorbed.

Patient's serum is positive for serum sickness when:

1. Absorption with boiled guinea pig kidney antigen - antisheep agglutinins are absorbed.


2. Absorption with boiled beef antigen - antisheep agglutinins are absorbed.

Patient's serum is normal but contains a high heterophile titer from other causes when:

1. Absorption with boiled guinea pig kidney antigen - antisheep agglutinins are absorbed.  In rare cases the absorption maybe incomplete.


2. Absorption with boiled beef cell antigen - antisheep agglutinins remain.

Thanks to modern technology, labtechs have the rapid slide Monospot test/ Monotest.

NEXT REACTION:  BACTERIAL AGGLUTININS

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