S Rauer1, R Kaiser. 1. Department of Neurology, Albert Ludwig University, 79,106 Freiburg, FRG. rauer@nz11.ukl.uni-freiburg.de
Abstract
OBJECTIVES: The aim of this study was to evaluate the suitability of an ELISA employing purified recombinant HuD antigen, for detection of specific anti-HuD antibodies in sera and cerebrospinal fluid (CSF) from patients with paraneoplastic neurological syndromes (PNS). MATERIAL AND METHODS: The cutoff for optical density readings was estimated by testing of 145 sera from healthy subjects. Sera from 17 patients with paraneoplastic neurological syndromes (PNS) and evidence of a clear anti-Hu band pattern in an immunoblot employing human cerebellar crude extract as antigen were tested. RESULTS: All 17 sera from patients with PNS revealed a clear positive result in the HuD-ELISA, demonstrating a sensitivity of 100%. Two out of 150 sera from patients with various infectious, autoimmune and neoplastic diseases (excluding PNS) showed a borderline result in the HuD-ELISA. This reveals a specificity of more than 98%. In addition 10 serum/CSF pairs from patients with anti-Hu-syndrome were adjusted to equal IgG concentrations and were tested in parallel in the HuD-ELISA. A specific antibody index (AI=ODCSF/ODserum) over 1.5 indicates intrathecal antibody synthesis. Six of ten patients revealed an AI >1.5, one was borderline (AI=1.5), and three had an AI in the range of 0.9-1.2. There appears to be a correlation between elevated AIs (>1.5) and presence of oligoclonal bands in the CSF. CONCLUSION: Due to its high specificity and sensitivity the recombinant HuD-ELISA is a suitable test for detection of anti-HuD antibodies in patients with putative PNS. In addition, the HuD-ELISA seems to be appropriate for the detection of specific intrathecal HuD-antibody synthesis.
OBJECTIVES: The aim of this study was to evaluate the suitability of an ELISA employing purified recombinant HuD antigen, for detection of specific anti-HuD antibodies in sera and cerebrospinal fluid (CSF) from patients with paraneoplastic neurological syndromes (PNS). MATERIAL AND METHODS: The cutoff for optical density readings was estimated by testing of 145 sera from healthy subjects. Sera from 17 patients with paraneoplastic neurological syndromes (PNS) and evidence of a clear anti-Hu band pattern in an immunoblot employing human cerebellar crude extract as antigen were tested. RESULTS: All 17 sera from patients with PNS revealed a clear positive result in the HuD-ELISA, demonstrating a sensitivity of 100%. Two out of 150 sera from patients with various infectious, autoimmune and neoplastic diseases (excluding PNS) showed a borderline result in the HuD-ELISA. This reveals a specificity of more than 98%. In addition 10 serum/CSF pairs from patients with anti-Hu-syndrome were adjusted to equal IgG concentrations and were tested in parallel in the HuD-ELISA. A specific antibody index (AI=ODCSF/ODserum) over 1.5 indicates intrathecal antibody synthesis. Six of ten patients revealed an AI >1.5, one was borderline (AI=1.5), and three had an AI in the range of 0.9-1.2. There appears to be a correlation between elevated AIs (>1.5) and presence of oligoclonal bands in the CSF. CONCLUSION: Due to its high specificity and sensitivity the recombinant HuD-ELISA is a suitable test for detection of anti-HuD antibodies in patients with putative PNS. In addition, the HuD-ELISA seems to be appropriate for the detection of specific intrathecal HuD-antibody synthesis.