Measurement and significance of antibodies against GM1 ganglioside. Report of a workshop, 18 April 1989, Chicago, IL, U.S.A.

Twelve laboratories from the United States, Canada, France, Italy and Switzerland participated in a workshop to compare assays used to measure anti-GM1 antibodies, and to discuss the clinical significance of these antibodies. A panel of test samples containing varying amounts of anti-GM1 antibody was prepared by mixing varied proportions of normal serum with a serum containing a monoclonal IgM antibody that bound GM1 ganglioside. Enzyme-linked immunosorbent assay (ELISA) data were supplied by eight laboratories and ten laboratories classified the sera as negative, weakly or strongly positive. Most laboratories correctly identified the two samples that contained the highest quantities of antibody, but there was considerable disagreement on the classification of the three samples with moderate or small amounts of antibody. The sensitivity of the assays varied considerably. The more sensitive assays did not use detergent in the washing buffers, and incubated the human serum with the antigen at 4 degrees C overnight. Several investigators have identified a subset of patients with lower motor neuron disease or multifocal neuropathy who have high titers of anti-GM1 antibodies. Many patients with neurological and non-neurological diseases have low to moderate levels of anti-GM1 antibodies, and the significance of these antibodies is unclear. There was general agreement that standardization of the ELISA assays is urgently required, and that distribution of a reference high-titered antiserum would facilitate this process.