What is Postzone phenomenon?
What is Postzone phenomenon?
Postzone phenomenon is defined as a false-negative test resulting from high antigen titre, which interferes with the formation of the antigen-antibody lattice, necessary to visualize a positive test.
What is zonal phenomenon?
: the occurrence of prozones in antibody-antigen mixtures.
What causes Postzone phenomenon?
The Post-zone Phenomenon is a false-negative test caused by excessive antigen, relative to antibodies, which prevents antibody-to-antigen crosslinking [4]. Crosslinking is necessary for immunochromatographic detection [4].
What is the difference between prozone and Postzone phenomenon?
Prozone – excess antibody to the available amount of antigen (no agglutination is a result) Zone of Equivalence – optimal amounts of both antibody and antigen (results in agglutination) Postzone – excess antigen to the available antibody (no agglutination is a result)
What is lattice hypothesis?
A hypothesis describing antigen‐antibody reactions in terms of the building up of large antigen‐antibody aggregates or three‐dimensional lattices. The hypothesis requires both antigen and antibody to have valencies greater than one.
What is the difference between Prozone and Postzone phenomenon?
What is Prozone and Postzone effect?
When there is excess amount of antibody or excess amount of antigen, the insoluble structure cannot be formed and the soluble complex fails to generate the desirable results. When antibody is in excess, we call it the prozone effect. When the antigen is in excess, we call it the postzone effect.
What is the zone of equivalence?
Definition of equivalence zone : the part of the range of possible proportions of interacting antibody and antigen in which neither or but small traces of both remain uncombined in the medium.
How do you test for prozone phenomenon?
Many hospital laboratories do not routinely test for the prozone phenomenon. This is performed by diluting the patient’s serum to bring the antibody concentration into the zone of equivalence.
Why is ouchterlony called double diffusion?
In the Ouchterlony double diffusion, both the antigen and the antibody diffuse toward each other in a semisolid medium to a point till their optimum concentration is reached. A band of precipitation occurs at this point.
What is the meaning of prozone phenomenon?
Medical Definition of prozone phenomenon. : the reduction in characteristic effect exhibited in the prozone of antibody-antigen mixtures. — called also prozone effect.
What is the prozone phenomenon in antibody excess?
In the case of antibody excess, the prozone phenomenon occurs, in which antigen combines with only one or two antibody molecules, and so no cross-linkages are formed.
What is the prozone phenomenon in the RPR test?
The prozone phenomenon in the RPR test was associated with the phase of syphilis, pregnancy, and neurosyphilis as well as a range of RPR titers between 1:8 and 1:512. This latter finding is in contrast to previous reports that the prozone phenomenon is associated with very high RPR titers.
What is the incidence of prozone phenomenon in syphilis?
Logistic regression was used to analyze the risk factors of the prozone phenomenon. Results. Our results showed that the incidence of the prozone phenomenon was low (0.83%) and could occur during any clinical phase, particularly during primary and secondary syphilis.
