Monitoring neutrophils and platelets during casein-induced anaphylaxis in an experimental BALB/c mouse model

Background With respect to the cellular players, mast cells and basophils have been well studied in experimental murine systemic anaphylaxis models, but the role of neutrophils and platelets is not fully understood today. Objective We tested the hypothesis that neutrophils and platelets might participate in an antigen-induced anaphylaxis model. Methods BALB/c mice were sensitized intraperitoneally with alum-adsorbed casein. A period of 2 weeks later, mice were challenged with 100 mu g casein intravenously and immediate hypersensitivity reactions were assessed by rectal temperature measurements and monitoring the physical activity. Subsequently, leucocytes were counted in the peripheral blood as well as quantified in situ in typical shock organs like lung, liver and spleen, heart and kidney. Results Mice sensitized with casein showed casein-specific IgG1, IgE, and IgG2a. When sensitized mice were specifically challenged with casein they developed immediate hypersensitivity reactions including drop of temperature and reduced activity. Furthermore, pronounced peripheral neutropenia and reduced platelet counts correlated with the severity of the hypersensitivity reactions. In the histological analyses of collected tissues we observed lung interstitial neutrophilia using Gr-1 staining. These events occurred specifically in mice sensitized and challenged with casein, in contrast to control groups. Conclusions On the basis of our data we suggest that in addition to mast cells and basophils, neutrophils and platelets participate in the anaphylactic response in this BALB/c mouse model. Platelet and neutrophils expressing relevant immunoglobulin receptors may therefore have a synergistic effect with allergen specific IgE as well as IgG antibodies in food-induced anaphylaxis. We suggest that management of these cells could be of clinical importance to handle anaphylaxis.