Radioimmunoassay of human myelin basic protein in tissue extract, cerebrospinal fluid and serum and its clinical application to patients with head injury

Abstract The development of a double antibody radioimmunoassay for myelin basic protein in tissue extract, cerebrospinal fluid and unextracted serum is described. Detection limits for the assays were: for tissue extract 3.1 ng, for cerebrospinal fluid 30 ng/ml and for serum 13.6 ng/ml. Specificity for myelin basic protein is suggested by lack of cross reactivity by tissues other than brain and presence of immunoactivity in cerebrospinal fluid and serum only in samples from patients with brain damage due to intracranial surgery or head injury. Immunoactivity in brain extracts and serum from patients with severe brain damage was indistinguishable from authentic myelin basic protein on serial dilution. Cross reacting material in cerebrospinal fluid samples differed from the authentic protein on serial dilution and on Sephadex G-100 chromatography, and may represent breakdown products of myelin basic protein. Mean serum concentrations of myelin basic protein in patients one day after head injury were significantly higher than in control patients with or without other neurological disease. Highest serum myelin basic protein concentrations were found in patients with severe primary intracerebral damage, with peak levels occurring 2–3 days after head injury. In patients with extracerebral haematoma, without intracerebral damage, the peak serum myelin basic protein concentrations occurred 7–10 days after injury. It is suggested that the measurement of serum myelin basic protein concentrations may be valuable in the management of patients after head injury.