Figure 1.

Cutaneous lesions in MRL-Fas^lpr mice share features with human discoid CLE. A. Gross cutaneous lesions in the intra-scapular area and ears in MRL-Fas^lpr mice. Histopathologically cutaneous lesions in MRL-Fas^lpr mice resemble the verrucoid variant of discoid lupus characterized by interface vacuolar changes (black arrowheads) with apoptotic keratinocytes (white open arrow), acanthotic epidermis (double headed arrow) with hyperkeratosis (V), hypergranulosis (#) and follicular plugging (*), superficial and deep, as well as perifollicular inflammatory infiltrates (arrows) and associated scarring alopecia with markedly reduced hair follicles (H) and dermal fibrosis (@). Representative photomicrographs from MRL-Fas^lpr mice (5 mo of age), H&E stained sections (n=18). Magnification: 20x, inset 40x. Inset in right panel: apoptotic keratinocytes, 60x. B. Positive lupus band (IgG and C3 deposits) at the dermal-epidermal junction in lesional and non-lesional skin of MRL-Fas^lpr mice (3 mo of age) determined by immunofluorescence staining. Representative of n=5–7. The pattern of IgM and IgG1 staining at the dermal-epidermal junction (data not shown) was more focal than IgG and C3. We did not detect a lupus band in BALB/c skin (data not shown). Stars indicate dermal-epidermal junction; dotted line the border of the epidermis to the environment. C. MRL-Fas^lpr skin is photosensitive. UVB ‚irradiation (6 consecutive days, 500J/m²) induces the lupus band (IgG, C3) as well as IgM and IgG1 (data not shown) at the dermal-epidermal junctions in MRL-Fas^lpr mice (2 mo of age), but not in BALB/c mice (data not shown). Representative of n = 4–6, experiment repeated twice.