Part I: to investigate the efficacy of different sunscreens in the prevention of skin lesions following standardized photoprovocation with Ultraviolet A/Ultraviolet B (UVA/UVB) light in patients with CLE.

Part II: to evaluate the influence of different sunscreens on the expression of biomarkers in the skin of patients with CLE and of Healthy Controls following UV irradiation.

Part I

Part I-interventions will be:

• Experimental intervention: Application of broad-spectrum sunscreens with a low, medium, and high Sun Protection Factor (SPF) in random order to uninvolved skin areas prior to standardized photoprovocation.
• Control intervention: Intra-individual application of vehicle in random order; standardized photoprovocation of vehicle treated and untreated areas.

Part II

Part II-interventions will be:

• Experimental intervention: Application of a broad-spectrum sunscreen with a high SPF to uninvolved skin areas prior to UV irradiation.
• Control intervention: UV irradiation of untreated areas.

Inclusion Criteria:

• Patients with subacute cutaneous lupus erythematosus (SCLE), discoid lupus erythematosus (DLE), or lupus erythematosus tumidus (LET) according to the Düsseldorf Classification 2004 (Kuhn and Ruzicka 2004) confirmed by histological analysis.
• Women of childbearing potential with a negative pregnancy test at screening (urine test) and using a medically accepted contraceptive regimen (intra-uterine device, partner's vasectomy, >3 months previous hormonal contraception (oestrogen plus gestagen pill, depot injections, or subcutaneous depot) combined with a barrier method (preservative, vaginal diaphragm, cervical cap, spermicide) during the study and for 8 weeks after the last UV exposure.
• Women clinically sterile (post-menopausal, undergone hysterectomy or tubal ligation).
• Actively cooperating to participate in the study, to follow the instructions of the investigator and to attend the centre at the agreed times.
• Development of skin lesions any time under current systemic treatment if patient is receiving systemic medication for the treatment of CLE.
• Signed informed consent form after the nature of the study has been fully explained.

Exclusion Criteria:

• Pregnancy or lactation and women with positive pregnancy test.
• Known hypersensitivity or allergic contact reactions to components of the study agents.
• Treatment with photosensitizing drugs.
• Exposure to direct natural (sunlight) or artificial UV radiation on the back within 4 weeks prior to entering the study.
• History of another photodermatosis, except polymorph light eruption (PLE).
• Any current known skin malignancy or any history of skin malignancy within the previous 5 years or Xeroderma pigmentosum.
• Initiation or change in the dose of any current systemic medication for the treatment of CLE within 8 weeks prior to standardized photoprovocation.
• Local therapy for the treatment of CLE within two weeks prior to standardized photoprovocation at the back of the patient
• Acute exacerbation of CLE skin disease within 2 weeks prior to entering the study.
• Acute illness within 7 days prior to phototesting or major illness including infection or hospitalization within 1 month of study entry.
• Anti-dsDNA (RIA) > 7 U/ml and/or at least one of the following criteria:
• Serositis: pleuritis or pericarditis documented by electrocardiogram or rub or evidence of pericardial effusion;
• Renal disorder: proteinuria greater than 0.5 g/d or greater than 3+, or cellular casts;
• Neurologic disorder: seizures or psychosis without other cause.
• Patients with a documented HIV and/or hepatitis B or C infection.
• Any medical condition, which would place the subject at undue risk of, or make it unlikely that follow-up-measurements could be obtained