ePoster Presentation 49th Annual Scientific Meeting of the Australian and New Zealand Society for Immunology 2021

Exposure to systemic immunosuppressive ultraviolet radiation alters T cell recirculation through sphingosine-1-phosphate (#211)

Scott N Byrne 1 2 , Benita CY Tse 1 , Rachael A Ireland 1 2 , Jun Yup Lee 1 , Felix Marsh-Wakefield 1 , Chris Kok 1 , Anthony Don 1 3
  1. University of Sydney, The University of Sydney, NSW, Australia
  2. Centre for Allergy and Immunology Research, Westmead Institute for Medical Research, Sydney, NSW, Australia
  3. The Centenary Institute, Sydney, NSW, Australia

Systemic suppression of adaptive immune responses is a major way through which ultraviolet (UV) radiation contributes to skin cancer development. Immune suppression is also likely to explain how UV protects from some autoimmune diseases such as multiple sclerosis. However, the mechanisms underlying UV-mediated systemic immune suppression are not well understood. Exposure of C57BL/6 mice to doses of UV known to suppress systemic autoimmunity led to the accumulation of cells within the skin-draining lymph nodes and away from non-skin‑draining lymph nodes. Transfer of CD45.1+ cells from non‑irradiated donors into CD45.2+ UV‑irradiated recipients resulted in preferential accumulation of donor naïve T cells and a decrease in activated T cells within skin‑draining lymph nodes. A single dose of immune suppressive UV was all that was required to cause a redistribution of naïve and central memory T cells from peripheral blood to the skin‑draining lymph nodes. Specifically, CD69‑independent increases in S1P receptor 1 (S1P1)‑negative naïve and central memory T cells occurred in these lymph nodes. Mass spectrometry analysis showed UV‑mediated activation of sphingosine kinase 1 activity, resulting in an increase in S1P levels within the lymph nodes. Topical application of a sphingosine kinase inhibitor on the skin prior to UV‑irradiation eliminated the UV‑induced increase in lymph node S1P and T cell numbers. Thus, exposure to immunosuppressive UV disrupts T cell recirculation by manipulating the S1P pathway.