Particulate Aspergillus fumigatus antigens elicit a TH2 response in BALB/c mice

In order to understand the immunoregulation in allergic aspergillosis, a murine model was developed by exposing animals to particulate and soluble antigens of Aspergillus fumigatus.

BALB/c mice were exposed to soluble Aspergillus antigen intranasally. Animals showing moderate levels of IgE were subsequently exposed to soluble antigen or antigen conjugated to polystyrene beads intranasally. The IgE and IgG1 in the sera and the eosinophils in the blood and lungs were studied. The spleen and lung mononuclear cells were stimulated with both concanavalin A and antigen and evaluated for production of interleukin (IL)-4, IL-5, IL-10, and interferon-gamma.

Animals exposed to particulate antigens showed more elevated serum IgE levels and increased numbers of eosinophils in the blood and lungs than those exposed to soluble antigen. Lung cell cultures from animals exposed to particulate antigens when stimulated with Aspergillus produced IL-4 and IL-5, indicating a TH2 type of response. Animals exposed to soluble antigens showed a weaker TH2 response, as evidence by low IgE levels in sera, fewer eosinophils in the blood, and low levels of cytokine production from lung and spleen cells.

The results indicate that the physical nature of the antigen may have a major role in determining the type of immune response of the host.