Regulatory T cells in paraneoplastic neurological syndromes.

Focusing on CD4(+)CD25(+) regulatory T lymphocytes (T(reg)), we studied the gene expression of T(reg) functional molecules in peripheral blood lymphocytes of patients with paraneoplastic neurological syndrome (PNS), including Lambert-Eaton myasthenic syndrome (LEMS) with small cell lung carcinoma (SCLC) and anti-Hu- or anti-Yo-antibody-positive PNS. T(reg)-rich subsets were sorted from the patients' peripheral blood mononuclear cells, and the mRNA expression levels of their functional genes were measured. The expression levels of FOXP3, TGF-beta and CTLA4 mRNA in T(reg)-rich subsets of PNS patients were down-regulated compared with that of SCLC patients without PNS. These results suggest that T(reg) dysfunction plays a role in PNS development.