Immunochemical assays for IgG, IgA, IgM and transferrin compared.
We compared immunochemical methods for determining IgG, IgA, IgM, and transferrin in serum by studying calibrator crossover, patient comparison, and, for a newly developed technology, normal reference intervals. For the immunoglobulins, we compared radial immunodiffusion (RID), rate nephelometry using the Beckman ICS, and a new nephelometric method adapted to the Abbott TDx; for transferrin we compared the ICS, TDx, and immunoturbiditry. The methods examined for quantifying IgA and transferrin showed good agreement in calibrator crossover and patient comparison studies. In studies comparing IgG methods, the ICS and TDx demonstrated acceptable agreement, although neither showed accordance with RID. For IgM determination, crossover studies and patients having less than 4300 mg/L in this protein showed good agreement, even though more elevated samples, run on the TDx, showed a discrepancy in proportionally compared to the other two methods. Normal reference intervals (95% confidence limits) determined on the TDx agreed well with those established for the other immunochemical methods.
Christenson
R H
RH
Department of Laboratory Service, Durham VA Medical Center, NC 27705.
Finley
P R
PR
Silverman
L M
LM
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D005779:Immunodiffusion; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D012015:Reference Standards; D014168:Transferrin / Q000097:blood*
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D014168:Transferrin