Diagnostic significance of IgG-synthesizing activated B cells in acute inflammatory diseases of the central nervous system.

An immunohistological technique was used to identify activated, i.e. IgG-synthesizing, B cells in cerebrospinal fluid. A total of 177 patients suffering from inflammatory diseases of the central nervous system were investigated. Activated B cells were found in 61% of patients with bacterial meningitis, especially in lethal or prolonged cases. The number of activated B lymphocytes was low in most cases of viral meningitis, whereas in tick-borne meningopolyneuritis Bannwarth, a very strong B cell activation was detectable. In all inflammatory diseases investigated, the B cell response was restricted to the mononuclear phase. Comparing the number of activated B cells and the amount of locally synthesized IgG, there was a loose correlation between these inflammation parameters in meningopolyneuritis Bannwarth. In acute viral and bacterial meningitis more than 50% of the patients exhibited activated B cells without any detectable intrathecal IgG synthesis.