Identification of granzyme B-expressing CD-8-positive T cells in lymphocytic inflammatory infiltrate in cutaneous lupus erythematosus and in dermatomyositis.

BACKGROUND

Lupus erythematosus (LE) and dermatomyositis (DM) are interface dermatitis, histologically characterized by formation of colloid bodies and a CD4+ CD8+ lymphocyte infiltrate. Colloid bodies are examples of intraepidermal apoptosis. Granzyme (Gr)B, synthesized by activated cytotoxic lymphocytes, is a serine protease able to prime apoptosis. GrB+ lymphocytes have been previously found in infiltrates in skin lesions from other types of interface dermatitis.

AIM: To evaluate, on histological skin specimens from patients with LE and DM, GrB expression as a mediator of keratinocyte apoptosis in lymphocyte infiltrate.

METHODS

In total, 22 patients with cutaneous LE [9 with discoid lupus erythematosus (DLE), 9 with subacute lupus erythematosus (SCLE) and 4 with systemic lupus erythematosus (SLE)] and 20 patients with DM were studied. Skin specimens underwent immunohistochemical staining with antibodies to CD3, CD4, CD8 and GrB.

RESULTS

Immunohistochemical study with GrB was positive in 17 of the 22 patients with LE but only 2 of the 20 patients with DM. In LE, in systemic and subacute forms of LE, the median obtained was < 10 (+) whereas in the chronic forms, the median was 10-50% (++). Patients with DM were negative for GrB.

CONCLUSIONS

In LE, a correlation between GrB+ lymphocyte and the presence of DLE form was found, but in DM, GrB is poorly expressed. GrB labels a subpopulation of effector cells involved in ongoing cytotoxic action and should be considered as a specific marker showing the extent of the direct local cytotoxic damage. GrB could play a role in the induction of skin apoptosis mechanisms in LE.