Aqueous .beta.2'-glycoprotein I composition

Abstract

A method for preparing an aqueous protein composition from human blood plasma, wherein the plasma undergoes a series of treatments by heating and precipitating agent to give albumin solutions containing the precipitating agent, and said precipitating agent is separated from the resulting solutions to give a crude aqueous albumin solution which is subjected to at least one liquid phase chromatography step to retain at least part of the secondary proteins other than albumin. The chromatography comprises affinity chromatography on a particulate support consisting of neutral particles loaded with at least one compound comprising sulphate groups, whereby, after the albumin solution has been fed through, the particulate affinity chromatography support is eluted by feeding through an aqueous saline solution, preferably by increasing the ionic strength, and the desired protein composition is collected by elution. A protein composition obtained by the method, an isolated glycoprotein having a molecular weight of 50,000.+-.3,000 daltons and contained in the composition, an agent for stabilizing albumin during a Tyndall effect treatment, and an agent for detecting and/or assaying antibodies by ELISA or immuno-imprinting, are also provided.

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