Effects of UVR on immune system

It seems that overall, the effects of UVR on our immune system is negative although there are some benefits.  Researchers at the Melanoma and Skin Cancer Research Institute (MASCRI) have found that even small doses of UVR cause significant immunosuppression in the skin.  A daily dose of UVR to cause mild sunburn for five days reduces the skin’s immune responses by approximately 40 percent.  This reduction in immune function is the same for all people no matter what the colour of their skin. 

In a study where people had twelve, 30 minute exposures to UVR in a commercial tanning bed, it was found that the functions of T cells and Natural Killer cells (these play an important role in fighting viral infections and are cytotoxic to some tumour cells) were negatively affected.   Other studies have similar findings: even a slight case of sunburn suppresses immune system protection against a variety of infectious diseases including tuberculosis, leprosy, malaria, measles, chicken pox, herpes and fungal diseases.  There is also concern that vaccination programs may be compromised.  UVA is the main cause of immunesuppression rather than UVB.  Some researchers suggest that Immune Protection Factor (IPF) may be a better measure of protection against skin cancer, rather than SPF.

It has been shown that the effects of UVR on the immune system are not all negative.  The effect of UVR on T-helper 1-mediated autoimmune disorders such as type 1 diabetes, multiple sclerosis and rheumatoid arthritis is beneficial.  UVR has a possible protective role for these diseases.