Elevated titers of anti-GM1 IgG-antibodies has been found in Guillain-Barré Syndrome patients (GBSp). Its primary role in disease process has been largely demonstrated. Although low-affinity anti-GM1 IgM-antibodies are present in all normal human plasma (NHP), they have no GM1-mediated biological activity. We found in a healthy plasma donor (N530) anti-GM1 antibodies of the IgG isotype, not observed in any other NHP analyzed. We studied their affinity and fine specificity in comparison with IgG-antibodies from GM1-immunized rabbits and GBSp, by using HPTLC-immunostaining of GM1 and structurally related glycolipids, soluble antigen binding inhibition, and GM1-affinity columns.
In the N530 plasma, the antibody-binding to the all three glycolipids was inhibited by soluble GM1 and GA1, as it has been seen with rabbit anti-GM1 IgG-antibodies. The affinity stimation of both antibodies were in the order of 10-
The affinity and isotype changes in N530 antibodies (as seen with rabbits) would not be enough to induce pathology (in contrast with GBSp antibodies). We hypothesize this unusual presence could be an intermediate stage between health and disease process onset, a fact predicted in the “Binding Site Drift” hypothesis (Lopez, et al. 2001, J.Neuroimmunol., in press)
