Patent ID: 7977279

Claim:
A method of identifying differences in expression of polypeptides between two samples, said method comprising: (a) providing one or more first arrays comprising one or more polypeptides from a first complex biological sample adhered to a first type of support; (b) providing one or more second arrays comprising one or more polypeptides from a second complex biological sample adhered to a second type of support; (c) exposing a phage display library comprising a plurality of members (i) to one of said first arrays at least one time to create a first product, said first product comprising one or more members of said phage display library that reversibly bind to said first array and (ii) to one of said second arrays at least one time to create a third product, said third product comprising one or more members of said phage display library that reversibly bind to said second array; and (d) exposing said first product to one of said second arrays at least one time to create a second product, said second product comprising one or more members of said first product that do not bind to said second array; (e) exposing said third product to one of said first arrays at least one time to create a fourth product, said fourth product comprising one or more members of said third product that do not bind to said first array; wherein a member of said phage display library in said second product binds to a polypeptide in said first biological sample that is expressed in a greater amount than in said second biological sample and a member of said phage display library in said fourth product binds to a polypeptide in said second biological sample that is expressed in a greater amount than in said first biological sample; (f) combining said second and fourth products to produce a pooled product; (g) providing one or more third arrays comprising one or more members from said pooled product adhered to a support; and (h) exposing said first or second complex biological sample to one of said third arrays at least one time to provide a fifth product, said fifth product comprising one or more polypeptides from said first or second complex biological sample that reversibly bind to said third array.