In humans 5 diff. types of antibodies have been found. IgE being one of them.
According to Schaums's
"IgE tends to promote the release of histamine by mast cells when it binds to its antigen. It has also been associated with the bodys fight against parasites as well as with allergic reactions. Antibodies are the primary weapon of the humoral response. They may attack an antigenic organism or molecule directly, or they may activate related systems..."