What Is the Prozone Phenomenon?

The prozone phenomenon is an effect that causes false negatives in immunological assays. Examples include high amounts of syphilis (i.e. a chronic contagious disease that produce chancres and rashes) antibodies in HIV patients.

Immunological Assays

• Abnormal levels of immunoglobulin in the blood serum can be caused by serious medical conditions such as myeloma. Assays are used to assess the level in order to diagnose or rule out a disease.

False Negatives

• A false negative would indicate that there was no problem when the immunoglobulin level was in fact abnormal.

Prozone Phenomenon

• The prozone phenomenon is a false negative in an assay caused by an extremely high concentration of the antibody or antigen involved in the test. This can happen in severe cases of myeloma, for example, as the increase in serum immunoglobulins can be very great.

Affected Assays

• The prozone phenomenon has been observed in immunoturbidimetric (i.e. a diagnostic test), one-step immunometric and immunophelometric assays. These are assays for immunoglobulins.

Detection

• The prozone phenomenon is detected by performing assays with both diluted and concentrated samples. If the result for the diluted sample is higher than the undiluted sample then this is probably due to the prozone effect. This check can be done with pooled samples in order to check many samples in one go.