Enzyme immunoassay for myelin basic protein in cerebrospinal fluid

Abstract

Myelin basic proteins (MBPs) are a set of proteins making up about 30% of the protein content of the central nervous system myelin. Four human isoforms have been identified [11]. The most abundant is a highly conserved 18.5 kDa polypeptide. For this species, the amino acid sequence homologies between human and monkey or human and chick are 98.2% and 71.1%, respectively [11]. As a consequence, there is a very good immunological cross-reactivity between the mammalian MBP. This protein has been extensively used to induce experimental allergic encephalomyelitis (EAE) in numerous animals [1, 4, 10]. The evolution of chronic EAE in animal is similar to that of multiple sclerosis (MS), a demyelinating human pathology, and chronic EAE is considered to be an animal model of MS [1, 10]. In demyelinating pathologies, MBP concentration in the cerebrospinal fluid (CSF) is considered to be a good marker of demyelination [7, 9, 14–16]. MBP concentration, in biological fluids, is generally determined by radioimmunoassay (RIA) [3, 8, 9]. The RIA technique currently used is highly sensitive (0.1–2.5 ng/ml) [2, 14]but has the drawback of requiring the handling of radioactivity and frequent labelling of MBP [2, 14]. So we developed a new enzyme immunoassay (EIA) technique. Our technique has the same sensitivity as RIA, needs only small volumes of CSF (50 μl) and the enzyme-labelled MBP tracer is stable for at least 12 months. © 1997 Elsevier Science B.V. All rights reserved.