Neuraminic Acid as a Constituent of Human Cerebrospinal Fluid.

Abstract

The neuraminic acid (NA) content of 49 samples of human cerebrospinal fluid (CSF) was studied. In all instances the quantitative relationship of neuraminic acid to the cerebrospinal fluid protein was far in excess of that prevalent in serum. In 26 samples in which the total protein was 30 mg % or less, the neuraminic acid was 4-18 times in excess of that expected if it were derived from serum and bound to protein, as is the case in blood. Unlike its state in serum, most of the CSF neuraminic acid is in freely dialyzable form (60-80%). That moiety of CSF neuraminic acid which is derived from serum is in protein-bound, nondialyzable form. The origin of the dialyzable NA is unknown, but is not related to ingress of serum proteins into the CSF. The implications of these findings are discussed.