The effect of ultraviolet radiation on the skin manifestations of patients with dermatomyositis.

In summary, we will determine the initial cutaneous response after UVB provocation of the skin. Specifically we will determine the trafficking of Langerhans cell, leucocytes and lymphocytes and the expression of MMP in skin lesions and compare these with healthy controls, patients with lupus erythematosus and patients with polymorphic light eruption, for which the results have already been obtained.

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In summary, we will use our phototest protocol for patients with DM;

1. To determine the minimal erythema dose (MED) for UVB, UVA, and visible light.

2. To determine the clinical aspect of the photoprovoked skin lesions.

3. To determine the time interval between the start of phototesting and induction of skin lesions until their resolution.

4. To record any adverse events.

The information thus acquired can be used to advice the patient more specifically on appropriate protection measures that can be taken against environmental UV radiation.

B. Determination of the cellular trafficking in the initial cutaneous inflammation induced by photoprovocation in patients with DM

After determination of the MED for UVB a test area of 5 cm square on the upper back will be exposed to 3 MED UVB.

Skin biopsies (4 mm.) will be taken of the test area at 0, 24, 48 and 72 hours after one single UVB exposure with 3 MED.
These skin biopsies will be compared with those of healthy controls, patients with lupus erythematosus and patients with polymorphic light eruption. The results for these groups have already been obtained.