title: Electrophoresis underestimates the concentration of polyclonal immunoglobulins in serum.
abstract: The concentration of gamma-migrating immunoglobulins in blood serum was measured in 200 healthy blood donors by two methods, nephelometry and electrophoresis. Nephelometric values were calculated as IgG + IgM + 1/2 IgA because immunoglobulin G (IgG) and immunoglobulin M (IgM) migrate entirely within the gamma region and immunoglobulin A (IgA) is split between the gamma and beta regions. Electrophoretic values were calculated as % gamma x total protein. Gels were scanned with two different densitometers, providing two sets of electrophoretic data. In each case, the correlation between nephelometry and electrophoresis was very good (r = 0.94 and r = 0.96). However, electrophoresis consistently gave lower results than nephelometry (mean = 2.3 g/L and 4.8 g/L lower, respectively). The disparity between these methods was greater as the concentration of immunoglobulins increased. It is concluded that (1) electrophoresis gives a relative but not absolute value of immunoglobulin concentration in serum; (2) nephelometric and electrophoretic values cannot be used interchangeably; and (3) reference ranges for electrophoresis must take into account the densitometer used.
authors.affiliation: Department of Pathology, Vancouver General Hospital, British Columbia, Canada.
authors.forename: W E
authors.initials: WE
authors.lastname: Schreiber
authors.forename: E
authors.initials: E
authors.lastname: Chiang
authors.forename: S S
authors.initials: SS
authors.lastname: Tse
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003720:Densitometry; D004586:Electrophoresis / Q000592:standards*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007120:Immunochemistry; D007136:Immunoglobulins / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D009994:Osmolar Concentration; D012016:Reference Values
chemical_list: D007136:Immunoglobulins