Autoreactive T and B cells responding to myelin proteolipid protein in multiple sclerosis and controls*
The pathogenesis of multiple sclerosis (MS) could involve an autoimmune response to proteolipid protein (PLP). Immunization of experimental animals with this major myelin protein can lead to experimental allergic encephalomyelitis.To identify a possible role of PLP as target antigen in MS, we evaluated Tcell immunity to PLP in blood and cerebrospinal fluid (CSF) from patients with MS and controls by counting cells which in response to PLP in short-term cultures secreted interferon-y. The PLP-specific B cell response was analyzed by counting cells secreting anti-PLP antibodies. PLP-reactiveT cells were detected in blood of most MS patients (mean value 1 per 20408 mononuclear cells), and at 41-fold higher numbers in CSF (mean 1 per 500 CSF cells). Anti-PLP IgG antibodysecreting cells were detected in blood from most MS patients (mean 1 per 30303 cells), but such cells were 49-fold more frequent in CSF (mean 1 per 625 cells). PLP-reactive T and B cells were also detected in blood and CSF from control patients, but at much lower numbers. A strong and persistent autoimmune response to PLP as well as to other myelin proteins, enriched in CSF, is proposed to be pathogenetically important in MS.