Patent ID: 8741810

Claim:
A method of selecting polynucleotides which encode an antigen-specific immunoglobulin molecule, or antigen-specific fragment thereof, comprising: (a) introducing into a population of eukaryotic host cells capable of expressing said immunoglobulin molecule a first library of polynucleotides encoding, through operable association with a transcriptional control region, a plurality of first immunoglobulin subunit polypeptides, each first immunoglobulin subunit polypeptide comprising: (i) a first immunoglobulin constant region selected from the group consisting of a heavy chain constant region and a light chain constant region, (ii) an immunoglobulin variable region corresponding to said first constant region, and (iii) a signal peptide capable of directing cell surface expression or secretion of said first immunoglobulin subunit polypeptide; (b) introducing into said host cells a second library of polynucleotides encoding, through operable association with a transcriptional control region, a plurality of second immunoglobulin subunit polypeptides, each comprising: (i) a second immunoglobulin constant region selected from the group consisting of a heavy chain constant region and a light chain constant region, wherein said second immunoglobulin constant region is not the same as said first immunoglobulin constant region, (ii) an immunoglobulin variable region corresponding to said second constant region, and (iii) a signal peptide capable of directing cell surface expression or secretion of said second immunoglobulin subunit polypeptide, wherein said second immunoglobulin subunit polypeptide is capable of combining with said first immunoglobulin subunit polypeptide to form an immunoglobulin molecule, or antigen-specific fragment thereof; (c) permitting expression of immunoglobulin molecules, or antigen-specific fragments thereof, from said host cells; (d) contacting said immunoglobulin molecules with an antigen; and (e) recovering those polynucleotides of said first library which express immunoglobulin molecules, or antigen-specific fragments thereof, specific for said antigen, wherein said first library or said second library comprises at least 10different polynucleotides.