Producing compositions comprising two or more antibodies

The invention relates to means and methods of producing at least two antibodies. Methods may include providing cells with nucleic acid that encodes the antibodies; culturing said cells; collecting the antibodies from the culture; and separating produced antibodies from half antibodies by ion exchange chromatography (IEX). In some embodiments the antibodies exhibit IEX retention times that that deviate by 10% or less from the average of the retention times of the individual antibodies under the IEX conditions used. The invention also relates to compositions of antibodies thus produced. In some aspects the invention relates to compositions comprising 2-10 recombinant antibodies characterized in that the IEX retention times of at least two of said antibodies deviate by 10% or less from the average of the retention times of the individual antibodies under the IEX conditions. It also relates to compositions comprising 2-10 recombinant antibodies characterized in that the p I of at least two of said antibodies differ by 0.4 units or less from the average p I of said at least two antibodies.