Automated PGP9.5 immunofluorescence staining: a valuable tool in the assessment of small fiber neuropathy?
(2016) BMC Research Notes —
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- Abstract
- Background: In this study we explored the possibility of automating the PGP9.5 immuno uorescence staining assay for the diagnosis of small ber neuropathy using skin punch biopsies. The laboratory developed test (LDT) was subjected to a validation strategy as required by good laboratory practice guidelines and compared to the well- established gold standard method approved by the European Federation of Neurological Societies (EFNS). To facilitate automation, the use of thinner sections. (16 μm) was evaluated. Biopsies from previously published studies were used. The aim was to evaluate the diagnostic performance of the LDT compared to the gold standard. We focused on technical aspects to reach high-quality standardization of the PGP9.5 assay and nally evaluate its potential for use in large scale batch testing. Results: We rst studied linear nerve ber densities in skin of healthy volunteers to establish reference ranges, and compared our LDT using the modi cations to the EFNS counting rule to the gold standard in visualizing and quanti- fying the epidermal nerve ber network. As the LDT requires the use of 16 μm tissue sections, a higher incidence of intra-epidermal nerve ber fragments and a lower incidence of secondary branches were detected. Nevertheless, the LDT showed excellent concordance with the gold standard method. Next, the diagnostic performance and yield of the LDT were explored and challenged to the gold standard using skin punch biopsies of capsaicin treated subjects, and patients with diabetic polyneuropathy. The LDT reached good agreement with the gold standard in identifying small ber neuropathy. The reduction of section thickness from 50 to 16 μm resulted in a signi cantly lower visualiza- tion of the three-dimensional epidermal nerve ber network, as expected. However, the diagnostic performance of the LDT was adequate as characterized by a sensitivity and speci city of 80 and 64 %, respectively. Conclusions: This study, designed as a proof of principle, indicated that the LDT is an accurate, robust and auto- mated assay, which adequately and reliably identi es patients presenting with small ber neuropathy, and therefore has potential for use in large scale clinical studies.
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