Protein A-sepharose used to measure free insulin in plasma.
Diabetic patients receiving insulin therapy generally develop anti-insulin antibodies that must be eliminated, usually by extraction with polyethylene glycol (PEG), before determining the concentration of free (active) insulin in plasma. We describe a new method for removing such antibodies, with the use of Protein A coupled to Sepharose microspheres. The results correlate well with those by the PEG method, although values are systematically higher or lower for given samples, according to the initial titer of the antibody measured in terms of binding capacity. Further studies are required to clarify this observation.
Chevenne
D
D
Service d'Explorations Fonctionnelles, Hôpital Necker-Enfants Malades, Paris, France.
Valade
F
F
Bridel
M P
MP
Rigal
O
O
Demelier
J F
JF
Sachs
C
C
Porquet
D
D
D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000302:isolation & purification; D007074:Immunoglobulin G / Q000302:isolation & purification; D007075:Immunoglobulin M / Q000302:isolation & purification; D007328:Insulin / Q000097:blood* / Q000276:immunology; D008297:Male; D011092:Polyethylene Glycols; D012685:Sepharose; D013205:Staphylococcal Protein A
D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007328:Insulin; D013205:Staphylococcal Protein A; D011092:Polyethylene Glycols; D012685:Sepharose