Identification of IgG-immunocomplex macroprolactin with an immunometric "sandwich" system: technical and clinical considerations.
MacroPRL can be due either to anti-PRL autoantibodies IgG (IgG-macroPRL) or other PRL containing molecules without IgG-PRL immuncomplexes (nIgG-macroPRL), the composition of which is not fully clarified. The aims of this study were: a) testing a new immunometric assay, capable of recognising IgG-macroPRL, b) looking for any biological and/or clinical discrepancy between nlgG-macroPRL and IgG-macroPRL. Clinical, biological and neuroradiological data were recorded from 28 hyperprolactinemic women classified as macroprolactinemic on the basis of PRL recoveries after polyethylene glycol (PEG) precipitation <50% on a Roche Elecsys analyser. Fourteen sera with recoveries >70% were employed as controls for the IgG-macroPRL assay. An immunometric "sandwich" assay for IgG-macroPRL was performed employing an anti-PRL antibody to capture PRL and a second one binding and tracing the immunoglobulin G (IgG) component. For this purpose, 2 kits were simultaneously employed, the first for PRL assay and the second for Anti-Toxoplasma IgG assay. The procedure was applied to both DiaSorin LIAISON and Abbott AxSYM systems. IgG-macroPRL immunometric detection was obtained with DiaSorin LIAISON. Twenty out of 28 (72%) sera gave luminescent signal higher than the maximum control serum and were considered as IgG-macroPRL carriers. Our results confirm the high IgG-macroPRL prevalence in macroprolactinemia. No significant clinical differences appear between IgG and nIgG-macroPRL. Conversely, significantly higher PRL values (p =0,039) and lower recoveries (p = 0.001) were found in IgG-macroPRL. Further studies with reference methods, such as gel chromatography and human IgG (h-IgG) affinity columns, are needed to fully validate this IgG-macroPRL immunometric assay.
Amadori
P
P
Outpatient Endocrinology Service, APSS, Trento, Italy. amadoripierluigi@libero.it
Dilberis
C
C
Marcolla
A
A
Pinamonti
M
M
Menapace
P
P
Valentini
A
A
D000328:Adult; D001323:Autoantibodies; D016022:Case-Control Studies; D002846:Chromatography, Affinity; D005260:Female; D006801:Humans; D006966:Hyperprolactinemia / Q000209:etiology* / Q000276:immunology; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000032:analysis / Q000276:immunology*; D047468:Immunoprecipitation; D011388:Prolactin / Q000032:analysis / Q000276:immunology*; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D007074:Immunoglobulin G; C060678:prolactin, polymeric; D011388:Prolactin