June 27, 2014

B Cell-Derived IL-15 Enhances CD8 T Cell Cytotoxicity and is Increased in MS

Researchers at the Centre Hospitalier de l'Universite de Montreal, Hopital Notre-Dame in Montreal investigated the involvement of interleukin-15, a cytokine, on CD8 T cells or 'killer T cells' as it relates to the mechanism of MS. [Raphael Schneider, Alma Nazlie Mohebiany, Igal Ifergan, Diane Beauseigle, Pierre Duquette, Alexandre Prat, and Nathalie Arbour. The Journal of Immunology, 2011, 187: 000–000.]

IL-15 is a type of protein secreted by white blood cells following an infection. Its function is to regulate T and natural killer cell activation and reproduction. The sources and involvement of cytokines such as interleukin-15 (IL-15) in activating the CD8 T cells (killer T cells) in MS is still unresolved.

To investigate the role of IL-15 in enhancing the activation of killer T cells in the context of MS, a research team from the Centre Hospitalier de l'Universite de Montreal lead by Drs. Raphael Schneider and Nathalie Arbour, analyzed the presence of IL-15 in the blood of people with MS and the impact IL-15 had on killer T cell function and migration. Analysis showed a significantly greater proportion of B cells and monocytes (white blood cells) from people with MS expressing IL-15 relative to the non-MS control group. The research team established that activation of B cells from the non-MS study group increased their IL-15 levels, reaching those of people with MS.

Drs. Schneider and Arbour also demonstrated an enhanced ability of killer T cells to cause toxic effects or death to cells in the central nervous system of people with MS upon stimulation with IL-15. They also found that exposure of killer T cells to IL-15 enhanced their ability to kill glial cells (cells found in the central nervous system) as well as migrate across the blood–brain barrier. These findings suggest a potential avenue of therapeutic strategies aimed to reduce sources of IL-15 in MS.