The normal cerebrospinal fluid proteins identified by means of thin-layer isoelectric focusing and crossed immunoelectrofocusing.

The cerebrospinal fluid and serum proteins from 32 healthy individuals have been examined by isoelectric focusing in a pH-gradient from 3.5--11.0. Seventeen normal proteins have been identified by means of crossed immunoelectrofocusing. The pI-values of the main fractions of these proteins have been determined. On crossed immunoelectrofocusing microheterogeneity was observed for all of the proteins except haemopexin, gamma-trace protein of CSF and prealbumin of serum. Differences between serum and CSF were observed for 6 of the proteins. Prealbumin of CSF had a lower pI-value than in serum and showed partial immunological identity with prealbumin of serum. Transferrin of CSF included several components with lower sialic acid contents than in serum. The conversion of C'3-complement from beta-1-C to beta 1-A was slower in CSF than in serum. Qualitative differences between CSF and serum were also noticed for alpha2-macroglobulin and haptoglobin. IgM was not detected in CSF. In CSF the gamma-trace protein was found on isoelectric focusing in one third of the subjects. Two subjects had 2 close tau-fractions and another two had one unidentified band in the anodal IgG-area. The gamma-trace protein did not show any proteolytic activity, nor any resemblance in charge to 4 basic enzymes or with the histones tested.