Quantitative relationships of the fourth complement component in human cerebrospinal fluid.

A technique for the measurement of cerebrospinal fluid C4 concentration in unconcentrated specimens has been developed with the methods of electroimmunodiffusion and immunofixation. The method has proved to be reproducible and requires only microliter volumes of undiluted cerebrospinal fluid (CSF). The mean value for CSF C4 concentrations in 16 neurologically normal individuals was 325 +/- 32 mug/100 ml. A positive correlation between CSF C4 concentration and the concentration of CSF albumin and total protein was observed. The positive correlation between the concentrations of CSF C4 and albumin was, however, more clearly defined than the relationship of CSF C4 to total CSF protein.