Method for the preparation of normal rabbit serum immunoglobulin M (IgM)

Abstract

A method for isolating rabbit non-immune serum IgM has been described. Normal serum immunoglobulins were precipitated with 18% Na 2SO 4, and were partially resolved by chromatography on DEAE-cellulose. A fraction eluted with 0.17 M phosphate-NaCl buffer, pH 6.9, subsequent to fractionation with buffers up to 0.15 M total salt, was enriched in IgM. This protein was rechromatographed on DEAE-cellulose, and IgM-enriched fractions were eluted with Tris-NaCl buffer, pH 8.6, at a total salt concentration up to 0.20 M. The material then was filtered through Bio-Gel P-200, which allowed a preparation comprising mainly IgM but contaminated with an 8 S component. Refiltration resulted in an antigenically pure preparation of IgM, and one which was contaminated slightly. The yield of the very pure IgM was about 0.025 mg/ml serum.