Preliminary Evidence for a Western Blot Diagnosis of Satoyoshi Syndrome Using SH-SY5Y Neuroblastoma Cell Lysate as the Antigen Source

<b>Background/Objectives</b>: Satoyoshi syndrome is a rare, autoimmune disorder currently diagnosed based on clinical criteria: painful muscle spasms, diarrhea, and alopecia. Two previous reports showed a specific immunoreactive band in three Satoyoshi syndrome patients using Western blot analysis, with brain homogenate as the antigen source. These findings could be the basis for a future diagnostic test. The aim of our study was to evaluate the efficacy of using SH-SY5Y cell lysate instead of brain homogenate for a potential laboratory test for Satoyoshi syndrome using the Western blot technique. <b>Methods</b>: Western blot analyses were conducted using brain homogenate, SH-SY5Y cell lysates, and differentiated SH-SY5Y cell lysates. Serum samples were obtained from three Satoyoshi syndrome patients, alongside control samples from thirty blood donors and six patients with other neurological conditions. <b>Results</b>: Sera from patients with Satoyoshi syndrome displayed a three-band pattern in the 70-100 kDa range. This pattern was reproducible across all tested antigen sources (brain homogenate, SH-SY5Y lysate, and differentiated SH-SY5Y lysate) but was not observed for the sera from the control groups. The bands were more visible when using either type of SH-SY5Y lysate compared to brain homogenate. No differences were found between the SH-SY5Y lysate and the differentiated SH-SY5Y lysate. <b>Conclusions</b>: Sera from our Satoyoshi syndrome patients showed a specific band pattern that could be used for a future evaluation of Satoyoshi syndrome using Western blot. The use of SH-SY5Y cell lysate vs. brain homogenate as an antigen source may improve visualization and reproducibility of the immunobands and be less costly.