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Johan Schiettecatte, Jean De Schepper, Brigitte Velkeniers, Johan Smitz, André Van Steirteghem
Rapid Detection of Macroprolactin in tHe Form of Prolactin-Immunoglobulin G Complexes by Immunoprecipitation with Anti-human IgG-Agarose
Immunoprecipitation with anti-human immunoglobulin G-agarose was evaluated for the detection of prolactin-immunoglobulin G (PRL-IgG) complexes in macroprolactinemic samples from hyperprolactinemic patients (prolactin measured using the automated Elecsys PRL assay; Roche Diagnostics, Mannheim, Germany). Using the polyethylene glycol (PEG) precipitation test on serum samples with PRL above 1000 mIU/l, we detected macroprolactin in 38 out of 175 samples with a recovery below 50%. Gel filtration chromatography on a subset of hyperprolactinemic samples confirmed that macroprolactin was the predominant immunoreactive form of PRL in samples which showed a recovery ?50%. In 37 out of 38 samples containing macroprolactin, immunoprecipitation with anti-human IgG (anti-hIgG)-agarose revealed a higher PRL-binding (19.1–91.3%) than in the sera containing monomeric PRL (<10%). In conclusion, we found that PEG precipitation detected macroprolactin in 21.7% of samples with elevated PRL levels as measured by the Elecsys PRL assay, and that in the vast majority of these samples the presence of PRL-IgG complexes could be demonstrated by immunoprecipitation with anti-hIgG-agarose. In view of the high prevalence of PRL-IgG complexes in hyperprolactinemic patients and the simplicity of the test, immunoprecipitation with anti-hIgG-agarose might play a role in the routine laboratory handling of hyperprolactinemic samples, especially with regards to PRL assays where PEG causes interference.
Clinical Chemical Laboratory Medicine, Walter de Gruyter
Print ISSN: 1434-6621
Volume: 39, 12/2001
Pages: 1244 - 1248