Association of CSF IgG concentration and immunoglobulin allotype in multiple sclerosis and optic neuritis

The cerebrospinal fluid (CSF) and serum from 64 patients with multiple sclerosis (MS) and 47 patients with monosymptomatic optic neuritis (ON) were analyzed for the distribution of allotypic determinants on IgG and compared to similar samples from 51 patients with other neurological diseases (OND) as well as to serum samples from 97 healthy controls. The results indicate a significantly increased frequency of the haplotypes Gm a;g and Gm a,x;g among MS patients ( P = 0.024) with an associated increase in relative risk for MS among individuals with the Gm a,(x);g haplotypes compared to those individuals without them ( P = 0.014). Among MS patients, those with the Gm a,(x);g haplotypes had significantly higher CSF levels of IgG than those without ( P = 0.016); levels of serum IgG did not covary with Gm haplotype. Two-way analysis of variance indicates that familial cases have significantly higher levels of CSF IgG than nonfamilial cases ( P < 0.001) and that familial cases with the Gm a,(x);g haplotypes have the highest CSF IgG levels ( P < 0.005). There was no correlation between Gm haplotype and CSF or serum IgG levels in patients with ON or OND. The allotype effects were independent of age at onset and duration of disease. In all patients, regardless of disease classification, the phenotypes found in serum samples were identical to those found in CSF samples. The data presented support the hypothesis that the etiology of MS has as one of its parameters an immunoregulatory/immunogenetic factor. The successful analysis of these various parameters will provide useful information not only about MS but also about general principles of human immune responsiveness.