[Analysis of intrathecal immunity].

The occurrence of an intrathecal immune reaction, specific to the central nervous system, may reflect either a contemporary systemic immune reaction or a local process directly related to the disease observed. Analysis of this reaction proceeds in 3 stages: the intrathecal production of immunoglobulins is assessed; the specific antibody activity of the intrathecal immunoglobulins is compared with that observed in serum; possible variations in components of complement are investigated. These different data are derived from the examination of serum and cerebrospinal fluid samples obtained simultaneously. The results of the analysis help in determining the cause of the disease, enable the severity and potential prognostic value of the immune reaction to be assessed and provide precise information on the influence of treatment on the course of the reaction. Several examples (syphilis, AIDS, measles panencephalitis, multiple sclerosis) illustrate these results.