On the chemical characterization of colloid cyst contents.

Colloid cysts of the third ventricle have been investigated by chemical characterization of the cyst contents using ELISA with monoclonal antibodies for certain carbohydrate epitopes as well as a polyclonal antiserum against peptide domains, and immunohistochemistry on the cyst wall using the same antibodies. Furthermore, the carbohydrate composition of one sample has been determined after gel filtration. The cyst contents reacted strongly with the monoclonal antibody for the sulfo-Lewis epitope, and with the antimucin polyclonal antiserum. In one case the cyst fluid exhibited a blood group A antigen. A sample of cyst wall obtained by biopsy showed strong immunoreactivity against sulfo-Lewis antigen, and the sialo-Lewis antigen. The presence of the S atom with its high atomic number relative to that of C, H, and O atoms, may contribute to the high density appearance of colloid cysts on CT-scans. The sulfo-Lewis and sialo-Lewis carbohydrate epitopes are known as ligands for selectins, involved in inflammatory processes, and may well account for the aseptic meningeal reaction that may follow spilling of cyst contents during operative evacuation. The carbohydrate epitopes exhibited by colloid cysts and their contents, have also been reported for the mucins of salivary glands, uterine cervix, gall bladder and colon, and therefore, are not inconsistent with the assumption of an endodermal origin of colloid cysts.