Isolating cells expressing secreted proteins

Abstract

A method of detecting and isolating cells that produce a secreted protein of interest (POI), for example, an antibody, comprising: a) constructing a cell line transiently or stably expressing a cell surface capture molecule, which binds the POI, by transfecting the cell line with a nucleic acid that encodes such cell surface capture molecule; b) transfecting said cell simultaneously or subsequently with a second nucleic acid that encodes a POI wherein such POI is secreted; c) detecting the surface-displayed POI by contacting the cells with a detection molecule, which binds the POI; and d) isolating cells based on the detection molecule.

What is claimed: 
     
         1 . A method of detecting or isolating a eukaryotic cell that produces an antibody, comprising:
 (a) providing a eukaryotic cell comprising (i) a nucleic acid encoding an antibody heavy chain, (ii) a nucleic acid encoding an antibody light chain, and (iii) a nucleic acid encoding a cell surface capture molecule, which comprises a membrane anchor and is capable of binding the antibody;   (b) culturing the cell under conditions in which the antibody and cell surface capture molecule are expressed, and an antibody-cell surface capture molecule complex is formed intracellularly and displayed on the cell surface;   (c) contacting the cell with a detection molecule, which binds to the antibody; and   (d) detecting or isolating the cell.   
     
     
         2 . The method of  claim 1 , wherein the cell is detected in step (d) by flow cytometry. 
     
     
         3 . The method of  claim 1 , wherein the membrane anchor is a transmembrane anchor or a GPI link. 
     
     
         4 . The method of  claim 1 , wherein the detection molecule comprises two molecules that bind each other and are differentially labeled. 
     
     
         5 . The method of  claim 1 , wherein the detection molecule is linked to a solid support or particle. 
     
     
         6 . The method of  claim 1 , further comprising contacting the cell with a blocking molecule that binds the cell surface capture molecule or the antibody to block diffusion of antibody between cells. 
     
     
         7 . The method of  claim 1 , wherein the nucleic acid encoding the cell surface capture molecule is introduced into the cell before the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain. 
     
     
         8 . The method of  claim 7 , wherein the nucleic acid encoding the cell surface capture molecule is stably integrated in the cell. 
     
     
         9 . The method of  claim 7 , wherein the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain are introduced into the cell simultaneously. 
     
     
         10 . The method of  claim 9 , wherein the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain introduced into the cell are included in the same vector or plasmid. 
     
     
         11 . The method of  claim 9 , wherein the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain introduced into the cell are included in different vectors or plasmids. 
     
     
         12 . The method of  claim 1 , wherein the nucleic acid encoding the cell surface capture molecule is introduced into the cell after the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain. 
     
     
         13 . The method of  claim 1 , wherein the nucleic acid encoding the cell surface capture molecule is introduced into the cell simultaneously with the nucleic acid encoding the antibody heavy chain and the nucleic acid encoding the antibody light chain.