Objective Satoyoshi syndrome is a rare, likely autoimmune disorder that is traditionally diagnosed based on clinical criteria: painful muscle spasms, diarrhea and alopecia. Two previous reports showed a specific immunoreactive band in three patients using Western blot analysis with brain homogenate. The aim of this study was to evaluate the efficacy of SH-SY5Y cell lysate as a potential substitute for brain homogenate in the diagnosis of Satoyoshi syndrome.

Methods Western blot analyses were conducted using brain homogenate, SH-SY5Y cell lysates, and differentiated SH-SY5Y cell lysates. Serum samples were obtained from three patients diagnosed with Satoyoshi syndrome, alongside control samples from thirty blood donors and six patients with other neurological conditions.

Results Sera from patients with Satoyoshi syndrome displayed a consistent three band pattern in the 70–100 kDa range. This pattern was reproducible across all tested substrates (brain homogenate, SH-SY5Y lysate, and differentiated SH-SY5Y lysate), but it was not observed for the sera from the control groups. The immunoreactive bands were more patent when using either SH-SY5Y lysate compared to brain homogenate. No differences were found between the SH-SY5Y lysate and differentiated SH-SY5Y lysate.

Conclusion SH-SY5Y cell lysate could be an alternative to brain homogenate for the immunodiagnostic evaluation of Satoyoshi syndrome. The use of SH-SY5Y cell lysate for Western blot analysis may improve visualization and reproducibility and have a lower cost.

Key messages

Satoyoshi syndrome is a rare disease currently diagnosed based only on clinical criteria

A biological marker test for Satoyoshi syndrome could lead to early diagnosis and treatment thus improving the outcomes.

SH-SY5Y cell lysate may be a better substrate than brain homogenate for Western blot based diagnosis of Satoyoshi syndrome.

The authors have declared no competing interest.

This study was funded by by a Diputacion Provincial de Albacete (Spain), Juan Carlos Izpisua Belmonte research grant (Ref 33501, 2021 and a research grant from the Research Commission of the Albacete General University Hospital, Spain (2015 Call).

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Comite de Etica de la Investigacion con medicamentos de la Gerencia de Atencion Integrada de Albacete, Servicio de Salud de Castilla - La Mancha, Albacete, Spain

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All data produced in the present study are available upon reasonable request to the authors