Non-recombinant human insulin-like growth factor binding protein concentrate

Abstract

A human insulin-like growth factor (IGF) binding protein stock solution and method of making the same include a non-recombinant human IGF binding protein-3 (nr-IGFBP-3) in an aqueous buffered medium. The concentration of the nr-IGFBP-3 in the stock solution ranges from about 16 micrograms per milliliter (μg/ml) to about 40 μg/ml. A kit includes a set of calibrators for nr-IGFBP-3. The set of calibrators includes the nr-IGFBP-3 in different concentrations that are within a range of from about 0.5 μg/ml to about 16 μg/ml, which is configured to span a suspected range of IGFBP-3 analyte levels in an immunoassay of patient samples.

What is claimed is: 
     
         1 . A human insulin-like growth factor (IGF) binding protein stock solution comprising:
 a non-recombinant human IGF binding protein-3 (nr-IGFBP-3) in an aqueous buffered medium having an nr-IGFBP-3 concentration ranging from about 16 micrograms per milliliter (μg/ml) to about 40 μg/ml.   
     
     
         2 . The human IGF binding protein stock solution of  claim 1 , wherein the nr-IGFBP-3 concentration is within a range of about 20 μg/ml to about 30 μg/ml. 
     
     
         3 . A set of calibration standards comprising the human IGF binding protein stock solution of  claim 1 , wherein each calibration standard of the set has a different concentration of the nr-IGFBP-3, the different nr-IGFBP-3 concentrations of the calibration standards in the set ranging from about 0.5 μg/ml to about 16 μg/ml. 
     
     
         4 . The human IGF binding protein stock solution of  claim 1 , wherein the human IGF binding protein stock solution is exclusive of recombinant IGF binding proteins. 
     
     
         5 . The human IGF binding protein stock solution of  claim 1 , wherein the aqueous buffered medium of nr-IGFBP-3 is exclusive of recombinant IGFBP-3. 
     
     
         6 . A set of calibrators for an IGFBP-3 analyte immunoassay, each calibrator of the set comprising the human IGF binding protein stock solution of  claim 1  diluted with a human serum diluent, wherein the nr-IGFBP-3 concentrations of the calibrators of the set are different, the different nr-IGFBP-3 concentrations being configured to span a suspected range of IGFBP-3 analyte levels in patient samples. 
     
     
         7 . The set of calibrators of  claim 6 , wherein the human serum diluent is an acid treated, charcoal absorbed human serum that is substantially free of IGF binding protein. 
     
     
         8 . A kit comprising a set of calibrators for human insulin-like growth factor (IGF) binding protein, each calibrator of the set comprising an aqueous solution comprising a non-recombinant human IGF binding protein 3 (nr-IGFBP-3), wherein a concentration of the nr-IGFBP-3 in each calibrator of the set is different, the different concentrations of the nr-IGFBP-3 in the set being within a range of from about 0.5 micrograms per milliliter (μg/ml) to about 16 μg/ml. 
     
     
         9 . The kit of  claim 8 , wherein the range of different concentrations of the nr-IGFBP-3 in the set of calibrators is configured to span a suspected range of concentrations of one or both of IGFBP-3 analyte and IGF-1 analyte in patient samples, the calibrators in the set being different dilutions of a human IGF binding protein stock solution having an nr-IGFBP-3 concentration ranging from about 16 μg/ml to about 40 μg/ml. 
     
     
         10 . The kit of  claim 8 , wherein each calibrator of the set further comprises a human serum diluent, the human serum diluent comprising an acid treated, charcoal absorbed human serum substantially free from IGF binding protein, the human serum diluent being in amounts configured to dilute the nr-IGFBP-3 to the range of the different nr-IGFBP-3 concentrations. 
     
     
         11 . The kit of  claim 8 , wherein the set of calibrators is exclusive of recombinant human IGF binding proteins. 
     
     
         12 . A method of forming a concentrate of a non-recombinant human insulin-like growth factor (IGF) binding protein 3 (nr-IGFBP-3) in aqueous solution, the method comprising:
 contacting an aqueous solution of one of human serum and IGF binding protein from the human serum with a porous matrix; and   collecting concentrated nr-IGFBP-3 in aqueous solution from the porous matrix, the collected nr-IGFBP-3 in aqueous solution having a concentration within a range of from about 16 micrograms per milliliter (μg/ml) to about 40 μg/ml.   
     
     
         13 . The method of forming an nr-IGFBP-3 concentrate of  claim 12 , wherein the porous matrix is one or more of an ultrafiltration disc, a filtration membrane and a sepharose-based resin. 
     
     
         14 . The method of forming an nr-IGFBP-3 concentrate of  claim 12 , further comprising providing the aqueous solution of human serum, wherein the aqueous solution of human serum is provided comprising mixing human serum with a first buffer solution, and wherein contacting the aqueous solution of human serum with the porous matrix comprises:
 applying the human serum in the first buffer solution to a chromatography column with a sepharose-based resin equilibrated with a second buffer solution to separate nr-IGFBP-3 from other serum proteins in the human serum;   eluting the nr-IGFBP-3 from the sepharose-based resin with a third buffer solution; and   applying the eluted nr-IGFBP-3 in the third buffer solution to a filtration membrane with an exchange buffer to buffer exchange and concentrate the nr-IGFBP-3 in aqueous solution.   
     
     
         15 . The method of forming an nr-IGFBP-3 concentrate of  claim 12 , further comprising providing the aqueous solution of IGF binding protein, wherein the aqueous solution of IGF binding protein is provided comprising:
 mixing the human serum with a saturated anti-chaotropic salt solution to form a mixture;   isolating the IGF binding protein from the mixture; and   reconstituting the isolated IGF binding protein in a buffer solution, and   wherein contacting the aqueous solution of IGF binding protein with the porous matrix comprises applying the reconstituted IGF binding protein in buffer solution to one or both of a filtration membrane and an ultrafiltration disc with an exchange buffer to buffer exchange and to concentrate nr-IGFBP-3 in aqueous solution.   
     
     
         16 . The method of forming an nr-IGFBP-3 concentrate of  claim 15 , wherein the saturated anti-chaotropic salt solution comprises an anti-chaotropic sulfate salt in water. 
     
     
         17 . The method of forming an nr-IGFBP-3 concentrate of  claim 15 , wherein the saturated anti-chaotropic salt solution comprises an ammonium sulfate salt in a sodium phosphate solution. 
     
     
         18 . The method of forming an nr-IGFBP-3 concentrate of  claim 12 , wherein contacting an aqueous solution of one of human serum and IGF binding protein from the human serum with a porous matrix comprises tangential flow filtration with a buffer exchange solution. 
     
     
         19 . The method of forming an nr-IGFBP-3 concentrate of  claim 12 , further comprising preparing a set of calibrators with the concentrated nr-IGFBP-3 solution, a concentration of the nr-IGFBP-3 in each calibrator of the set being different, the different concentrations of the nr-IGFBP-3 in the set being within a range of from about 0.5 μg/ml to about 16 μg/ml, the set of calibrators being configured to calibrate measurement of one or both of IGFBP-3 and IGF-1 in patient samples. 
     
     
         20 . The method of forming an nr-IGFBP-3 concentrate of  claim 19 , wherein preparing the set of calibrators comprises diluting the concentrated nr-IGFBP-3 solution with different quantities of an acid treated and charcoal absorbed human serum diluent that is substantially free of IGF binding protein.