DERMAL MAST-CELLS IN SCLERODERMA - THEIR SKIN DENSITY, TRYPTASE CHYMASE PHENOTYPES AND DEGRANULATION/

To determine the distribution, tryptase/chymase phenotypes and degranu lation of mast cells (MCs) in the dermis of patients with scleroderma, we examined MC density in the skin of 22 patients with systemic scler osis (SSc) and 11 with localized scleroderma (LSc). We used antitrypta se and antichymase antibodies after Carnoy's fixation. Detailed report s of two representative patients with SSc and LSc are included. In the scleroedematous stage (grade 1) showing oedema in both papillary and reticular dermis with variable homogenization of collagen bundles in t he reticular dermis, MC skin density was variable in each specimen alt hough MC skin density, as a whole, was significantly increased as comp ared with normal skin (P<0.05). In the sclerotic stage (grade 2) chara cterized by homogenization of collagen bundles in the entire dermis, M C skin density was significantly decreased as compared with normal ski n (P<0.005). LSc showed changes similar to those in SSc. The ratio of MCTC cells (both tryptase- and chymase-positive MC) to MCT cells (tryp tase-positive but chymase-negative MC) was variable in SSc and LSc, MC T cells were exclusively dominant in three patients with SSc and two w ith LSc. In a patient with SSc (patient 1) showing remarkable perivasc ular and interstitial oedema in the upper dermis, MC skin density was increased in the oedematous portion and tryptase-positive granules wer e distributed in extracellular locations. In another patient with LSc (patient 2), tryptase positivity increased and chymase positivity decr eased in both number and intensity as the skin sclerosis progressed. M Cs must have variable interactions with the lesional skin in SSc and L Sc. The present study suggests that MCs are involved in the developmen t of interstitial oedema.