Sun
sensitivity and lupus disease often go hand in hand. Sun
sensitivity and UV light sensitivity (photosensitivity)
is present in about 90 percent of patients with systemic
lupus erythematosus (SLE), 40 to 60 percent of patients
with discoid lupus, and about 70 percent of patients
with subacute lupus erythematosus. Lupus sun sensitivity
causes patients to be more likely to get sunburn after
sun exposure and for the sunburn to last for a prolonged
period of time.
In systemic lupus
disease, sun exposure causes the classic
lupus
butterfly shaped rash that extends across the cheeks and
bridge of the nose. In
lupus discoid, sun exposure
causes coin-shaped (discoid) lesions in exposed areas.
In subacute lupus disease, sun exposure causes red, raised,
circular lesions on the back, chest and arms, which can
be confused with psoriasis. In addition, in lupus, sun
exposure may cause other rashes, as well as joint pain
and increased fatigue.
What is lupus
disease? In patients with
lupus disease, sun exposure, even for as little as 30 minutes,
causes them develop a migraine headache, feel nausea or
experience painful joints. In lupus, sun may cause an
increase in the activity of the disease (flare). This
may cause an acute attack of arthritis, pleurisy (chest
pain when inhaling), fever, kidney disease, and
epilepsy.
Scientists think that ultraviolet light (which is in
sunlight, fluorescent lights, photocopiers, and VDUs)
create antigens (protein molecules) on the skin surface
which react with antibodies. The antibodies cause white
blood cells to be drawn to the skin and attack it and a
rash appears. The redness and inflammation may also be
due to excessive nitric oxide present in the skin after
lupus patients are exposed to sun. In lupus disease, sun is more
likely to cause problems than artificial sources of
light.
The UV rays in sunlight causes damage to the skin (keratinocytes),
resulting in sunburn. In normal people, the sunburn goes
away because the dead skin cells get cleared away
quickly. In lupus disease, sun causes the damage to skin cells
but the cells are not cleared away very well. The
releases of the contents of the cells cause
inflammation. In addition, the cell contents, which
include Ro, are able to cause an immune response. The
immune system responds to the cells by creating autoantibodies which attack the skin.
Prolonged sun exposure by those that work outdoors
causes as three-fold increase in a Caucasian's chances
of developing systemic lupus erythematosus, according to
a study done by Patricia Fraser, M.D. published in
February, 2003 issue of The Journal of Rheumatology. For
people who already have lupus disease, the sun and UV
light can cause or worsen
rash lupus symptoms and systemic symptoms.
In patients with
lupus disease, sun exposure causes them to have antibodies to
Ro. In addition, other tissues in the body are affected
because auto-antibodies travel to other tissues in the
body, binding to target molecules and creating immune
complexes. The immune complexes cause inflammation and
the systemic symptoms of lupus. The reason why, in
lupus, sun exposure only causes rashes on some parts of
the body and not others is not known. It is also known
why in lupus, sun exposure does not always cause
sensitivity.
Sun exposure causes rashes in about 60 percent
of those with lupus disease. Other problems are reported by about 10 to
20 percent of patients with lupus after sun exposure.
However, the effects of sun exposure may not show up for
a couple of weeks.
If you have lupus, sun exposure should be limited in
order to prevent rashes and to prevent the disease from
going into an active phase. You should stay out of the
sun as much as possible, wear protective clothing and
sunscreens (SPF 25 or greater), and stay out of the
mountains and away from sunny countries, where UV
exposure is at its greatest. It is also wise to be aware
that reflected light from snow and water magnifies the
exposure. In addition, if you have lupus, sun exposure
can be reduced by putting UV film on windows.
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