Immunohistochemical distribution of S-100 alpha-positive cells in bovine mycobacterial and non-mycobacterial granulomas

Expression of cellular components in granulomatous inflammatory response in Piaractus mesopotamicus model

The present study aimed to describe and characterize the cellular components during the evolution of chronic granulomatous inflammation in the teleost fish pacus (P. mesopotamicus) induced by Bacillus Calmette-Guerin (BCG), using S-100, iNOS and cytokeratin antibodies. 50 fish (120±5.0 g) were anesthetized and 45 inoculated with 20 μL (40 mg/mL) (2.0 x 10⁶ CFU/mg) and five inoculated with saline (0,65%) into muscle tissue in the laterodorsal region. To evaluate the inflammatory process, nine fish inoculated with BCG and one control were sampled in five periods: 3^rd, 7^th, 14^th, 21^st and 33^rd days post-inoculation (DPI). Immunohistochemical examination showed that the marking with anti-S-100 protein and anti-iNOS antibodies was weak, with a diffuse pattern, between the third and seventh DPI. From the 14^th to the 33^rd day, the marking became stronger and marked the cytoplasm of the macrophages. Positivity for cytokeratin was initially observed in the 14^th DPI, and the stronger immunostaining in the 33^rd day, period in which the epithelioid cells were more evident and the granuloma was fully formed. Also after the 14^th day, a certain degree of cellular organization was observed, due to the arrangement of the macrophages around the inoculated material, with little evidence of edema. The arrangement of the macrophages around the inoculum, the fibroblasts, the lymphocytes and, in most cases, the presence of melanomacrophages formed the granuloma and kept the inoculum isolated in the 33^rd DPI. The present study suggested that the granulomatous experimental model using teleost fish P. mesopotamicus presented a similar response to those observed in mammals, confirming its importance for studies of chronic inflammatory reaction.

Dendritic cell involvement in pulmonary granuloma formation elicited by bacillus calmette-guérin in rats

Dendritic cells (DCs) are the most potent antigen-presenting cells that play a central role in initiating the primary immune response. However, their role in granulomatous inflammation has not been well studied. The aim of the present study was to elucidate the role of DCs in granuloma formation. Using a rat model of bacillus Calmette-Guérin (BCG)-elicited pulmonary granulomas, we investigated the distribution of DCs in the granulomas by immunohistochemistry with a rat-DC-specific monoclonal antibody, OX62. We found numerous large, pleiomorphic OX62(+) cells accumulating at the borders of the pulmonary granulomas. The OX62(+) cells isolated from the granulomatous lung showed intense surface expression of major histocompatibility complex class II, B7-1, and B7-2, and a lack of T cell- and monocyte/macrophage-specific markers. Their ultrastructural morphology was characteristic of DCs. Functionally, they had potent capacity to stimulate allogeneic T cells as well as purified protein derivative-specific syngeneic T cells in the absence of exogenous peptides. Based on these findings, the OX62(+) cells infiltrating the granulomas were considered to be DCs expressing BCG-derived peptides. These results indicate that DCs contribute to pulmonary granuloma formation elicited by BCG by means of their potent antigen-presenting function, providing a novel insight into DC function in T cell-mediated granulomatous immune responses.