Patent ID: 6962789

Claim:
A method for determining the quantity of a target protein in cells of a biological sample, the method comprising the steps of: (a) immunohistochemically staining said target protein in a plurality of control cell pellets using a detectably labeled antibody directed against said target protein, wherein the quantity of the target protein in the plurality of control cell pellets is independently known, and wherein the expression level of the target protein in each of the plurality of control cell pellets is not the same, (b) identifying pixels corresponding to cellular area to be determined for each of the stained plurality of control cell pellets in (a); (c) determining an average optical density of stained target protein per pixel of cellular area identified in (b) for each of the stained plurality of control cell pellets in (a); (d) generating a calibration curve relating the known quantity of said target protein with said average optical density of stained target protein per pixel of cellular area as determined in (c) for each of the plurality of control cell pellets; (e) immunohistochemically staining said target protein from said biological sample using said detectably labeled antibody directed against said target protein; (f) identifying the pixels corresponding to the cellular area to be determined in said biological sample; (g) determining an average optical density of stained target protein per pixel of cellular area identified in (f) in said biological sample; (h) determining the quantity of said target protein in said biological sample by comparing the average optical density of stained target protein per pixel of cellular area as determined in step (g) in said biological sample to the calibration curve as generated in step (d), wherein the quantity of said target protein is derived from the calibration curve.