A quantitative assay for low levels of IgM by solid-phase immunofluorescence.

A quantitative immunofluorescent assay capable of detecting between 15 and 1450 ng of IgM on a strictly linear standard curve has been developed. The assay system is unique in that in vitro biosynthesized polyclonal IgM in culture supernatants can be quantitated with a minimal quantity of supernatant. Interference created by lectins and bead-surface interactions have been analyzed. This easily operated assay has been validated and is reliable. A very important feature of the system is the considerable cost reduction in comparsion with radiometric techniques.