Changes in cell-mediated immune responses after experimentally-induced anaphylaxis in dogs

Immunophenotyping of skin-infiltrating T-cell subsets in dogs with atopic dermatitis

Atopic dermatitis in dogs has many clinical features that are identical to those of the same disorder in man. To investigate the pathogenesis of this disease in dogs and the possibility of similarities to the pathogenesis in humans we compared the presence and ratio of CD4+ and CD8+ T-cells in the cutaneous infiltrate of lesional and non-lesional skin of atopic dogs with that in the skin of healthy dogs. In ten dogs with atopic dermatitis and ten healthy dogs the skin was biopsied at the predilection sites for atopic dermatitis and histological sections were immunohistochemically stained for CD4 and CD8. The staining showed an increase in CD4+ and CD8+ T-cells in canine lesional atopic skin, with a predominance of CD4+ T-cells in the epidermis. In non-lesional atopic skin there was also an infiltration with CD4+ and CD8+ T-cells, but without predominance of CD4+ T-cells. The results in the separate predilection sites did not differ substantially from the mean results. These observations indicate further similarities in the immunopathogenesis of atopic dermatitis in dogs and humans, which may have consequences for the control of atopic dermatitis in dogs and contributes to a possible role of the dog as a model for human atopic dermatitis.

Canine leucocyte histamine release: response to antigen and to anti-IgE

Histamine release from canine leucocyte-enriched peripheral blood preparations was measured in atopic, non-atopic and artificially sensitised dogs after immunological challenge with D. farinae antigen and anti-IgE. Total cell histamine and spontaneous histamine release was also measured. The total cell histamine content of equal leucocyte preparations was not statistically significant between the atopic and non-atopic groups. At all dilutions of antigen a higher amount of histamine was released from the leucocytes of atopic dogs than was seen in the non-atopic group. No histamine release in response to D. farinae was seen in the sensitised dogs although a statistically significant increase in serum D. farinae-specific IgE could be demonstrated after sensitisation (P < 0.03). Histamine release in response to anti-IgE was significantly greater in the atopic dogs than the non-atopic dogs (P < 0.004) and the sensitised dogs (P < 0.003). There was no statistically significant difference in total serum IgE between the groups. The authors conclude that the leucocytes of atopic dogs have a greater tendency to release histamine than those of normal and artificially sensitised dogs and that this is independent of the concentration of total serum IgE or antigen-specific IgE. They suggest that there may be immunoregulatory abnormalities in atopic dogs intrinsic to the atopic state as is described in man.