EFFECTS OF UV IRRADIATION WITH ONE MINIMAL ERYTHEMA DOSE ON HUMAN AFFERENT SKIN LYMPH IN-VIVO

Ultraviolet (UV) irradiation of the skin induces complex local and sys temic immunomodulatory reactions. The biological effects of UV irradia tion on human skin derived afferent lymph however are unknown. The aim of this study was to examine the effects of a single combined WA and UV-B irradiation with 1 minimal erythema dose (MED) on human skin deri ved lymph in vivo. After cannulation of a superficial lymph vessel on the lower leg, lymph flow and cell output per hour were determined bef ore and for 6 days after UV irradiation of the lymph draining skin are a in 5 volunteers. Furthermore, expression of CD1a, CD4, CD8, CD28, CD 54, CD80, CD86 and HLA-DR on migrating lymph cells and cytokine levels (IL-1 alpha, IL-1 beta, IL-2, IL-6, IL-8, IL-10, IL-13, TNF-alpha and IFN-gamma) in the afferent lymph were analyzed by cytofluorometry and ELISA. After UV irradiation a small initial enhancement in the daily lymph flow per hour was noticed in correlation with the slight erythem atous skin reaction. Following resolution of the skin reaction, a dela yed increase in cell output in correlation with an additional peak in the lymph flow was found between the 4th and 6th day after UV irradiat ion. However, no changes in the expression of CD1a, CD4, CD8, CD28, CD 54, CD80, CD86 and HLA-DR on migrating lymph cells were detectable. In terestingly, in parallel to the increased lymph flow and cell output, only elevated IL-8 protein levels were reproducibly detected in the af ferent lymph after UV irradiation. Furthermore, using immunohistochemi stry positive staining for IL-8 was found on migrating mononuclear lym ph cells. In conclusion, our data demonstrate that a single UV irradia tion of the skin with 1 minimal erythema dose leads to a delayed enhan cement of lymph flow, number of migrating lymph cells and cytokine lev els of IL-8. Moreover, we provide evidence that migrating lymph cells, besides resident epidermal and dermal cells, may contribute to the de tected levels of IL-8 in the efferent lymph.