There are different triggers for those diagnosed with Lupus, and a common trigger is sunlight. What is it about the sunlight the causes the body to start attacking itself? Does the body not know how to process vitamin D? Does it wear them out faster by dehydrating them? Is there a scientific explaination for Lupus sun triggers?
Very interesting question. Thank you.
The pathophysiology of photosensibility in lupus patients is related to the effect of ultraviolet radiation (UVR) on cells of the immune system. UVR stimulates lymphocytes recruitment and antibody-mediated cytotoxicity, which are involved in the pathogenesis of lupus.
The mechanisms by which ultraviolet-A (UVA) (320–400 nm) and ultraviolet-B (UVB) (290–320 nm) induces photosensibility are however different. Following picture provides a good overview of our current understanding:
Recently, a review written by Kim et al (from which the above figure was taken), addressed the issue of photosensibility in patients with cutaneous lupus erythematosus. The paper is open-access if you wish to have further information (in particular on the possible treatments):
Kim A, Chong BF. Photosensitivity in Cutaneous Lupus Erythematosus. Photodermatology, photoimmunology & photomedicine. 2013;29(1):4-11. doi:10.1111/phpp.12018. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539182/