Autoreactive IgG to intracellular proteins in sera of MS patients

IgG binding to multiple protein constituents in lysates of Jurkat cells was detected by Western blot in sera of patients with multiple sclerosis (MS) and systemic lupus erythematosus(SLE). The distribution patterns of bands w ith sera tested against protein lysates from normal Jurkat cells or from Ju rkat cells exposed to apoptosis or oxidative stress inducing conditions wer e similar in most patients, but with inter-individual differences. The numb er of bands with sera of both patient populations far exceeded those (0 or 2 bands) detected with sera of healthy controls. Proteinase K, RNase and DN ase pre-treatment of cell lysates suggested a protein nature for all of the antigens and a ribonucleoprotein (RNP) nature for some of the antigens rec ognized by serum IgC of MS and SLE patients. Only two MS patients had posit ive anti-nuclear antibody (ANA) titers, while all of them had positive West ern blots. In addition to similarities, dissimilarities were also recognize d between the humoral immune responses in MS and SLE. No IgG molecules were detected against phosphorylated proteins in the sera of MS patients, while multiple phosphoproteins were recognized by Ige molecules of SLE patients in immunoprecipitation experiments These data suggest that in addition to A NA, the sera of MS patients contain autoantibodies directed against multipl e intracellular proteins. The protein recognition patterns of immunoglobuli ns in MS share similarities,but also have distinct features when compared t o those in SLE. The biological significance of these autoantibodies in MS r emains to be understood. (C) 1999 Elsevier Science B.V. All rights reserved .