Mast cells and their mediators. Emphasis on their role in type I immediate hypersensitivity in canines

The vesicular monoamine transporter 2 (VMAT2) is expressed by normal and tumor cutaneous mast cells and Langerhans cells of the skin but is absent from Langerhans cell histiocytosis

Monoamine storage in secretory granules is mediated by the vesicular monoamine transporters 1 and 2 (VMAT1 and VMAT2). The aim of our study was to identify monoamine-handling normal and neoplastic inflammatory cells in the skin by their expression of VMAT1 and VMAT2. Normal skin from various parts of the body, as well as 21 cases of cutaneous mastocytosis and 10 cases of cutaneous Langerhans cell histiocytosis were analyzed by immunohistochemistry, radioactive in situ hybridization, and double-fluorescence confocal microscopy. VMAT2-positive cells in the subepidermal layer were identified as mast cells by their expression of tryptase. Neoplastic mast cells in all cases of cutaneous mastocytosis retained their VMAT2 positivity. The intraepidermal VMAT2-expressing cells were identified as Langerhans cells by their CD1a positivity. VMAT2 was absent from Langerhans cell histiocytosis. VMAT2 is an excellent marker for normal and neoplastic mast cells. The expression of VMAT2 demonstrates the capacity of mast cells for monoamine storage and handling. The presence of VMAT2 in epidermal Langerhans cells revealed a previously unrecognized monoamine-handling phenotype of these cells and indicates possible involvement of amine storage and release associated with antigen presentation. Absence of VMAT2 in neoplastic Langerhans cells indicates a loss of monoamine handling capacity of these cells during tumorigenesis.

Immunohistological analysis of mast cell numbers in the intratumoral and peritumoral regions of prostate carcinoma compared to benign prostatic hyperplasia

Recently, some studies reported the presence of mast cells in various malignancies and their role in tumor growth. The aim of the study was to determine the utility of mast cell numbers in evaluating benign and malignant prostate lesions, and to ascertain whether there are variations in the numbers of mast cells with the Gleason grade. The relationship between mast cell numbers and patient age was also investigated. Retrospectively, 104 prostate specimens were examined for the presence of mast cells. The study group consisted of 57 benign prostatic hyperplasias and 47 prostate carcinomas. The paraffin sections were stained with anti-human mast cell tryptase immunohistologically. The numbers of positively staining cells in five high-power fields were counted, and their mean was calculated. There was no relationship found between mast cell numbers and age statistically. The mean mast cell numbers of the intratumoral region were significantly different from those of the peritumoral region (p = 0.0001). While the difference between benign hyperplasia and the intratumoral region was found to be significant (p = 0.0001), no difference between hyperplasia and the peritumoral region was noted (p = 0.762). There was no statistical difference between Gleason score groups (p = 0.452), and there was no interaction between score groups and intraperitumoral regions (p = 0.355).