IMMUNOGLOBULIN-G ISOTYPE CHANGES IN HUMAN SPORADIC AMYOTROPHIC-LATERAL-SCLEROSIS (ALS)

Out of 50 patients with sporadic amyotrophic lateral sclerosis (sALS), excluding 8 patients with recent immunosuppressive medication or low total IgG, we examined all available 92 sera of 1 1 women and 31 men n ephelometrically for serum immunoglobulin concentrations including IgG isotypes IgG(1-4). Mean serum levels of IgA and IgM remained within r eferences in all cases. Isotypes IgG(1) and IgG(3) were the most frequ ently altered immunoglobulins. Without specific treatment, 34 out of 4 2 patients ( = 80%) and 58 out of 92 sera ( = 63%) demonstrated low Ig G(3) concentrations ( < 0.41 g/l), while 14 patients ( = 33%) and 20 s era ( = 22%) demonstrated low IgG, serum levels ( < 4.22 g/l). In pati ents with normal total IgG, isotypes IgG, and IgG, often changed in a complementary way, and IgG(1)/IgG(2) serum concentrations correlated s ignificantly (r(s) = -0.518, P < 0.001). In four longitudinally monito red patients, the IgG(3) isotype ranged from 1.3% to 8.2% of serum IgG and demonstrated a remarkable individual variability over time, corre sponding to the relatively short half-life of IgG(3). Since elevated c irculating immune complexes may fluctuate rapidly, altered serum immun oglobulin isotypes could become more convenient parameters in a still enigmatic disease. To assess their role and relevance, their associati on with clinical course, cerebrospinal fluid and circulating immune co mplexes has to be examined.