T cell-dependent activity of ganglioside GM1-specific B cells in Guillain-Barré syndrome and multifocal motor neuropathy in vitro.

Synthesis of anti-ganglioside GM1 antibodies of the IgM class by peripheral blood mononuclear cells (PBMNC) from patients with immune-mediated neuropathies and motor neuron diseases and from normal controls was stimulated by Pokeweed mitogen (PWM) in vitro. In patients with acute Guillain-Barré syndrome or multifocal motor neuropathy and high serum titers of IgM anti-ganglioside GM1 antibodies this culture response was greatly enhanced as compared to controls and already detectable in unstimulated cultures. Limiting dilution analysis demonstrated high frequencies of GM1-specific B cells in these patients. Anti-ganglioside GM1 antibodies of the IgG and IgA class were only produced by PBMNC from patients with Guillain-Barré syndrome corresponding to serum titers. In cultures taken at intervals over 6 months in vitro B cell activity for IgM, IgG and IgA anti-ganglioside GM1 antibodies in two Guillain-Barré syndrome patients declined accompanied by clinical improvement and falling serum titers. We conclude that GM1-specific PWM-responsive B cells pre-exist in peripheral blood and respond to T cell-dependent stimulation in Guillain-Barré syndrome and multifocal motor neuropathy.