Relative frequency of autoantibodies to myelin basic protein and proteolipid protein in optic neuritis and multiple sclerosis cerebrospinal fluid

Myelin basic protein (MBP) and proteolipid protein (PLP) were purified from non-MS human brain and used in solid phase radioimmunoassays to detect their specific antibodies in cerebrospinal fluid (CSF) of optic neuritis and clinically definite multiple sclerosis (MS) patients. In 53 optic neuritis patients free anti-MBP was elevated in 47 and in 6 of these 47 patients bound anti-MBP was also increased. The remaining 6 patients with undetectable anti-MBP had increased levels of anti-PLP in their CSF. None of these optic neuritis patients had autoantibodies to both antigens. Of 173 MS patients with acute relapses 169 had increased free anti-MBP. Three of the 4 remaining patients with undetectable anti-MBP had increased anti-PLP in their CSF. Of 110 MS patients with chronic progressive disease, 107 had increased CSF anti-MBP and 2 had elevated anti-PLP. Of 87 MS patients in remission, 15 had modestly elevated anti-MBP and none had detectable anti-PLP. Considering the total of 370 clinically definite MS patients with active and inactive disease, 77% had increased CSF anti-MBP and 1% had increased CSF anti-PLP. These findings are suggesting 2 immunochemically distinct forms of MS: a common form with autoantibodies directed against MBP and a more rare form associated with anti-PLP.