[Cerebrospinal fluid proteins form the colloidal benzoin reaction to the present: a study of intrathecal immunity]

The benzoin reaction, described by Guillain, Laroche and Lechelle (1920) was probably the first test evaluating local (intrathecal) immunity in inflammatory diseases of the nervous system. Significant advances have taken place during the past 25 years: 1) Exact and precise determination of cerebrospinal fluid total protein by Lowry's method, and separation of gamma-globulins by precipitation or electrophoresis with identification of the oligoclonal aspect, the picture of intrathecal IgG synthesis. 2) Immunochemical determination of immunoglobulins and complement components by electro-immunodiffusion and detection of intrathecal anti-nucleic acid antibody synthesis. Different empirical formulae have been proposed to evaluate the intrathecal immunity. This evaluation allows: 1) a neuro-immunological classification of cerebrospinal fluid patterns. 2) a better appreciation of evolutivity in some neuro-immunological diseases (e.g. multiple sclerosis). 3) an evaluation of the antibody specific activity (ASA) and a comparison between this ASA in plasmatic and in intrathecally synthesized IgG. The study of complement components, also, can give some informations on the evolutivity of the immunological processus, suggesting, in some patients, an intrathecal formation of immune-complexes.