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Title: The effects of ultraviolet-B irradiation on the immune response to viral infections
Author: Halliday, Katrina E.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1998
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Cytokine mRNA profiles in both an in vitro and an in vivo model of HSV infection were studied. A mouse keratinocyte cell line (PAM-212) and mouse back skin were infected with HSV-1 and RNA was extracted at various times thereafter from lysed cells or skin homogenates. The expression of IL-10 mRNA in vitro peaked at 12 hours post-infection, and an increase in mRNA expression in the skin was seen from 96 hours post-infection. This would suggest that HSV-1 is inducing keratinocytes in the epidermis to produce IL-10 and this may represent a possible immune evasion strategy of HSV-1 by diverting the immune response away from a Th1 type response, known to be effective for viral clearance. UVB exposure of PAM-212 cells induced IL-10 mRNA by 24 hours. To study the effects of UVB exposure on the functional activity of human epidermal cells (EC) to act as antigen presenting cells, the mixed skin lymphocyte reaction (MSLR) was used. In vitro irradiation of EC appeared to suppress the MSLR to near background levels. In vivo irradiation of subjects with 0.5 MED for seven days on the subsequent skin blister site, also caused some suppression of the MSLR. Urocanic acid (UCA) has been proposed as a photoreceptor for UV radiation and cis-UCA mimics some of the effects of UVB on the immune system. Treatment of EC with cis-UCA in vitro caused suppression of the MSLR by an average of 71%. Normal subjects, known to be seropositive for HSV, underwent a standard course of broadband UVB phototherapy, as used in the treatment of psoriasis. They received whole body irradiation three times a week, with incremental doses depending on skin type. The ability of these individuals to mount an HSV-specific cytotoxic T cell response was examined, using autologous B cell lines infected with HSV-1 as targets. The cytotoxic response was not altered in all four subjects examined to date. However, the natural killer cell activity was suppressed within the first week of phototherapy, further suppressed at four weeks, but returned to the pre-irradiation value within a week after the final UVB exposure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available