Detection of CSF Leakage by Isoelectric Focusing on Polyacrylamide Gel, Direct Immunofixation of Transferrins, and Silver Staining

Abstract

Leakage of cerebrospinal fluid (CSF) from the subarachnoid space into the nasal or aural cavity creates a pathway for life-threatening central nervous system infection. Detection of the leakage can be cumbersome (1). In former days the identification and localization of CSF leakage was almost entirely dependent upon the clinical history and methods involving intrathecal injection of radioactive material or a dye. Furthermore, various chemical tests, such as determination of glucose, protein, and electrolytes, performed on the secreted material have been advocated for the differentiation between CSF leakage and other secretions (2). The injection methods are risk-bearing for the patient and the above methods yield a considerable chance of false-positive or false-negative results (3). Nowadays O -sialotransferrin, also named β2-transferrin, asialotransferrin, or the τ fraction, is an accepted marker protein for the detection of CSF in excretions from the nose or the ear, or from head or neck wounds. O -Sialotransferrin is not strictly unique to CSF. The protein can also be demonstrated in human aqueous humor (4) and in perilymph fluid (5)(6)(7). It is also found in the blood of patients with chronic liver diseases (8)(9), with an inborn error of glycoprotein metabolism (10), and with a genetic variant of transferrin (8)(11)(12). The protein can be detected by direct immunofixation of transferrins after agarose electrophoresis (high-resolution electrophoresis, HRE) (3)(13) or after blotting (1)(14)(15). The method we used up to now was the agarose/immunofixation method according to Zaret et al. (3). We used the Paragon High Resolution Electrophoresis kit (HRE kit, Beckman Instruments) and an anti-transferrin reagent (Beckman Array® System, Beckman Instruments). One disadvantage of this fast method is the high …