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 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.
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