Producing monoclonal antibodies includes their efficient and simple purification. Growing hybridoma cells in media containing Prolifix, an alternative plant-based substitute for serum, provides supernatants containing large amounts of antibodies and defined low molecular weight additives. Antibodies can easily be separated from these compounds by fast ultrafiltration. However, DNA originating from lysed cells is present in substantial amounts and must be removed for most antibody applications. The present communication provides a fast, cheap, and efficient separation method by precipitating the DNA from a phosphate buffered solution with manganese chloride. Resulting antibodies have a high purity and an unchanged bioactivity. The method is especially valuable for antibodies which lose bioactivity by interactions with chromatographic matrices (as, for example, Sepharose) and can be used for various antibody isotypes.