Mast cells in systemic and cutaneous lupus erythematosus.

Mast cells (MCs) are known to be regulators of inflammation and immunity, due to the released mediators and expressed cell surface molecules. Lupus erythematosus (LE) is a group of diseases which can be systemic or limited to the skin. Due to the fact that cytokines and chemokines produced by inflammatory cells contribute to the pathogenesis of LE, we quantified the number of mast cells present in the skin. The aim of the study was to compare the chymase-positive and tryptase-positive mast cell counts within skin biopsies from patients with systemic lupus erythematosus (SLE), discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE). The material consisted of 45 skin biopsies: 6 with SLE, 34 with DLE and 5 with SCLE. Chymase- and tryptase-positive cells were stained by immunohistochemistry and counted. The mean count of chymase-positive mast cells was 85.14 hpf for the whole group, 35.83 for SLE, 88.48 for DLE and 121.6 for SCLE. The mean count of tryptase-positive cells was 120.05 hpf for the entire group, 59.17 for SLE, 126.42 for DLE and 149.8 for SCLE. The differences between groups were significant for chymase- and tryptase-positive cells.