Accuratezza diagnostica di un’immunofissazione urinaria semplificata per la ricerca e tipizzazione della proteina di Bence Jones

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ABSTRACT

Diagnostic accuracy of a simplified urine immunofixation for the Bence Jones (BJ) protein detection and typing

We assessed the diagnostic accuracy of a modified routinely used commercial kit to screen for BJ. The study consisted in the revision of 1077 urine immunofixation that included antisera against free light chains (full IF), performed with Sebia Hydragel 2/4 BJ kit according to the manufacturer’s instructions. Two experts reassessed all gels, comparing the results of the full IF against those obtained excluding the lanes treated with the anti-free light chain antisera (simplified IF). 886 samples were negative and 123 samples were positive with both tests. One false negative sample was observed by the simplified IF, while 67 samples could not be interpreted using this type of IF. Sensitivity and specificity of the simplified IF were 99.3% and 94.8% respectively. On the basis of the obtained results, the following algorithm to screen for BJ can be suggested: simplified IF as first step followed by a full IF only in case of inconclusive results (e.g. in presence of monoclonal bands reacting both with heavy and total light chain antisera or elevated concentrations of polyclonal immunoglobulins). By using the simplified IF alone, 86.6% of positive samples would have been typed correctly without the need of a full IF.

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