[Polyspecific response in the central nervous system. Use of antibody index]

The immune response, oligoclonal in cerebrospinal fluid (CSF), in comparison with the blood evidences is different and polyspecific. Together with specific antibodies against the causative agent, antibodies with many different specificities were synthesized. It is more complex in chronic neurological diseases.

Broadcast the characteristics of the polyspecific oligoclonal response and the use of antibody index as diagnostic tool in infectious and chronic diseases.

The use of antibody index discriminates between the blood-derived antibody fraction and the brain-derived specific antibody fraction. Once the CSF/serum specific antibody and the IgG ratio are calculated, the antibody index is the quotient between both ratios. Antibody specific ratio may be obtained by titulation but it is less sensible. It is much better to employ immunoenzymatic methods. To avoid false negative results we must use the limit ratio according to reibergram instead of IgG ratio when the last one is greater than the limit ratio. Pathological antibody indexes are > or = 1.5. In chronic, autoimmune diseases, like lupus eritematosus, Sjögren syndrome or Wegener granulomatosis, could exist pathological antibody index against different viral agents like the antibody index against measles (M), rubella (R) and zoster (Z) viruses, known as MRZ reaction.

The use of antibody index permits the diagnosis of infectious neurological diseases and the characterization of the secondary polyspecific response in chronic neurological processes.