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A man in his 20s gave a 9-year history of recurrent muscle pain and weakness, occurring mostly after exercise, and lasting for up to 2 days. There had been one episode of severe rhabdomyolysis after cold exposure. He also had longstanding hypokalaemia, which was key to his correct diagnosis but was not followed. This case highlights the importance of an appropriately methodical investigation of weak hypokalaemic patients, and the relevance of hypokalaemia as a cause of neuromuscular symptoms not related to muscular channelopathies.

Objective To identify the most relevant antigens for monoclonal antibodies in lymphocytic infiltrates in non-systemic vasculitic neuropathy (NSVN). Background Current immunosuppressive treatment for NSVN is insufficient. Monoclonal antibodies might be a treatment option, but the expression profile for targetable antigens on lymphocytic infiltrates in NSVN is unknown. Methods Sural nerve biopsies from a cohort of patients with NSVN were immunohistochemically studied for the expression of potential candidate antigens in perivascular and intramural lymphocytic infiltrates and correlated with neurological and electrophysiological parameters. 20 patients with treatment naive NSVN and 5 patients with idiopathic axonal neuropathy were included. Results The CD52, BAFF and CD49d antigens were expressed in epineurial, perivascular or intramural lymphocytes of all (20/20) patients. CD52 was most prominently expressed in 21.49% of all inflammatory infiltrates. BAFF and CD49d were detected in 11.25% and 10.99% of these lymphocytes, respectively. The CD20, CD25 and CD126 antigens were found less frequently and at low levels only (CD20: 10/20 patients, 5.84% of lymphocytes; CD25: 17/20 patients, 5.22% of lymphocytes; CD126: 3/20 patients, 0.15% of lymphocytes). Conclusion This is the first study in NSVN that identifies antigens expressed by pathogenic lymphocytes, which are potential targets for future monoclonal antibody treatment. Our data suggest that NSVN is amenable to monoclonal antibodies and, moreover, that targeting CD52 may be particularly promising. Our results strongly warrant future clinical trials in NSVN with monoclonal antibodies.