DETECTION OF PARANEOPLASTIC ANTINEURONAL AUTOANTIBODIES ON PARAFFIN-EMBEDDED TISSUES

Anti-neuron-specific autoantibodies are widely recognised as useful, t hough non-specific, diagnostic markers of paraneoplastic neurological disorders. However, controversies on the best way to detect these auto antibodies have recently arisen, and the use of different procedures f or their detection by different laboratories has made results difficul t to compare. The aim of this study was to adapt the existing immunohi stochemical techniques used for the detection of anit-neuron autoantib odies to improve their visualisation and to facilitate a wide applicat ion of these procedures. Sera and cerebrospinal fluid (CSF) were obtai ned from 15 patients known to carry paraneoplastic anti-neuronal autoa ntibodies; in addition, one serum with ''atypical'' anti-neuron autoan tibody and 18 control sera were studied. Paraformaldehyde-fixed, paraf fin-embedded rat nervous tissue and formalin-fixed, paraffin-embedded human nervous tissue treated in a microwave oven were used as substrat e; the reactions were developed by immunoperoxidase methods. At the di lutions used for diagnostic purposes, all the sera and CSFs showed sta ining whose intensity and specificity was comparable to that obtained using frozen tissue; the end-point dilutions were, however, reduced. T he atypical pattern of staining of one serum was confirmed and better emphasised using these procedures; all control sera and CSFs were nega tive. The morphology was improved by the use of paraffin-embedded tiss ues; moreover, the results obtained are permanent because of peroxidas e staining, which makes it possible to use them as standards for furth er investigations and for comparison between different laboratories. T he convenience of using paraffin-embedded material could facilitate a wide application of these procedures in clinical neurology.