Elevated numbers of regulatory T cells, central memory T cells and class-switched B cells in cerebrospinal fluid of patients with anti-Hu antibody associated paraneoplastic neurological syndromes

•Absolute counts of T cell, B cell and DC subsets in CSF of Hu-PNS patients.•Numbers of B cells, T cells and DCs in CSF of Hu-PNS patients are elevated.•Most B and T cells in CSF of Hu-PNS patients have a memory phenotype.•Numbers of regulatory T cells in CSF of Hu-PNS patients are increased.•Our results on CSF in Hu-PNS resemble those in other CNS inflammatory diseases.

Multi-parametric flow cytometry was used to study lymphocyte subsets and dendritic cells in paired blood and CSF samples from 11 newly diagnosed patients with progressive anti-Hu antibody associated paraneoplastic neurological syndromes (Hu-PNS), 9 patients with other inflammatory neurologic disorders (IND), and 12 patients with other non-inflammatory neurologic disorders (OND). Hu-PNS patients had elevated numbers of regulatory T cells, central memory T cells, class-switched B cells and dendritic cells in their CSF. These findings support the hypothesis that the immune system is locally activated in Hu-PNS, and suggests common etiological pathways between Hu-PNS and other inflammatory central nervous system disorders.