An acute infectious illness frequently precedes the Guillain-Barré syndrome. Recently, Campylobacter jejuni was claimed to be a predominant precipitating agent that may also trigger a humoral immune response to glycoconjugates of peripheral myelin in Guillain-Barré syndrome. Because of conflicting reports, we determined the frequency of a recent infection with C. jejuni in 38 patients with Guillain-Barré syndrome using a highly sensitive and specific immunoblot technique, and of the presence of circulating antibodies to gangliosides. We detected IgM and/or IgG C. jejuni directed antibodies in 15 of 38 patients with Guillain-Barré syndrome. In contrast, only 7 of 39 healthy control subjects, 3 of 20 patients with multiple sclerosis, and 2 of 72 patients with neuroborreliosis showed IgA or IgM antibody responses to C. jejuni. In Guillain-Barré syndrome, C. jejuni-specific antibodies were predominantly directed to outer membrane proteins of one specific serotype, Lior 11, whereas the most common serotype associated with enteritis in Germany is Lior 4. Two of 27 patients with Guillain-Barré syndrome had ganglioside-specific IgA antibodies; 1 of 32 patients, antibodies of IgM; and 4 of 31 patients, antibodies of IgG class. There was no correlation between severity, type (axonal versus demyelinating), and outcome of the disease and the presence or absence of a humoral immune response to C. jejuni or to glycoconjugates. Our findings do not support previous suggestions that a preceding C. jejuni infection heralds a poorer outcome or that antibodies to gangliosides carry prognostic significance.(ABSTRACT TRUNCATED AT 250 WORDS)