Inmunohistochemical study of digestive lesions of cetaceans stranded in the Canary islands

Abstract

The nature of the cellular infiltrate (lymphocyte populations, macrophages and immunoglobulin-bearing plasma cells) observed in natural cetacean diseases only have been studied in common dolphins (Delphinus delphis) and striped dolphins (Stenella coeruleoalba) with hepatic disorders. The aim of this study was to examine the distribution and cross-reactivity of a panel of commercially available antibodies (CD3, IgG, IgM, IgA, S-100 protein, MHC class II and lysozyme) in lymph nodes and digestive lesions observed in common dolphins (Delphinus delphis), striped dolphins (Stenella coeruleoalba) and spotted dolphins (Stenella frontalis) found stranded along the coasts of the Canary Islands. The avidin-biotin-peroxidase (ABC) method was used. Dolphin mesenteric lymph node and healthy digestive tissue sections were used as positive controls. Chronic parasitic gastritis and lymphoplasmacytic enteritis were diagnosed. Chronic parasitic gastritis was granulomatous type, affecting mucosa, submucosa and muscular layer, with variable amount of lymphoplasmacytic infiltrate and fibrosis. The inflammatory infiltrates was composed mainly by CD3+ T lymphocytes and IgG+ plasma cells, being moderate to sparse the presence of IgM+ and IgA+ plasma cells sited in lamina propria of glandular areas of the stomach. The immunoreactivity with lysozyme and MHC class II was variable in macrophages observed in granulomata lesions and fibrotic areas. The anti-S100 protein pAb yielded a diffuse nuclear and cytoplasmic immunoreactivity in stellate cells, similar to follicular dendritic cells, located in these areas, suggesting that these infiltrates were highly organised to enhance antigen presentation to B and T cells. Lymphoplasmacytic enteritis was characterised by an inflammatory infiltrate composed of CD3+ T lymphocytes and IgG+, IgM+ and IgA+ plasma cells in lamina propria and submucosa. The anti-lysozyme reacted with sparse number of macrophages and monocytes in lamina propria, and ocasionally, in submucosa. The anti-MHC class II labelled moderate to sparse number of macrophages located in lamina propria, but no lymphocytes were labelled with this antibody.