Conjugated detergent micelles as a platform for IgM purification

Immunoglobulin M (IgM) antibodies hold promise as anticancer drugs and as agents for promoting immune homeostasis. This promise has not been realized due to low expression levels in mammalian cells producing IgM class antibodies, and the failure of protein A chromatography for IgM purification. Here, we describe a nonchromatographic platform for quantitatively capturing IgMs at neutral pH, which is then recovered with 86%–94% yield and >95% purity at pH 3. The platform contains micelles conjugated with the [(bathophenanthroline)3:Fe2+] amphiphilic complex. Inclusion of amino acid monomers, for example, phenylalanine or tyrosine, during conjugation of detergent micelles, allows subsequent extraction of IgMs at close to neutral pH. With the successful implementation of this purification platform for both polyclonal humans and bovine IgMs, we anticipate similar results for monoclonal IgMs, most relevant for the pharmaceutical industry. Immunoglobulin M (IgM) antibodies are rarely used in medicine due to difficulties associated with their expression and purification. A potentially (a) general, (b) nonchromatographic, (c) ligand‐free, and (d) simple‐to‐implement platform capable of quantitatively capturing IgMs (pH 7) and recovering these in pure form (>95%) at pH 3 (>95% yield) is presented. Unlike other purification methodologies, specially designed micelles conjugated via amphiphilic [metal:chelator] complexes are used.