CLINICAL-VALUE OF SPECIFIC INTRATHECAL PRODUCTION OF ANTIBODIES

The production of intrathecal antibodies is considered a highly specif ic marker for an infection of the central nervous system (CNS), e.g. b orreliosis or tick-borne encephalitis (TBE). To investigate the validi ty of this assumption, we examined records of patients who had been ho spitalized between 1989 and 1995, who were tested for borreliosis (n = 8003) and TBE (n = 904) and whose cerebrospinal fluid (CSF) had subse quently tested positive for intrathecal production of antibodies. The time period between the beginning of the symptoms and the time of the CSF examination ranged from one day to six weeks. Seventy-seven patien ts showed a production of intrathecal antibodies against Borrelia burg dorferi. Three of these patients were false positives with no history and no clinical signs of neuroborreliosis. In two cases, this was due to a non-specific cross-reaction caused by a preceding infection with syphilis. The third false positive was possibly caused by an earlier a dministration of immunoglobulins. Three patients showed a production o f intrathecal antibodies against TBE virus. Two of these patients were false positives. In one case, we suspect that the production of intra thecal antibodies was caused by a non-specific immune reaction during an acute neuroborreliosis. One year earlier, the patient had contact w ith TBE virus through a vaccination against TBE. The cause of the seco nd false positive is unclear, the clinical findings, acute encephaliti s and the serological analysis suggest a cross-reaction with a virus s imilar to TBE. A specific intrathecal production of antibodies is not a proof for an infection of the CNS. In unclear cases, one should carr y out a Western blot analysis or, if one suspects a case of TBE, a neu tralization test.