Type V (Stimulatory Type) Hypersensitivity
In this type of hypersensitivity reaction, antibodies combine with antigens on cell surface, which induces cells to prolifer-ate and differentiate and enhances activity of effector cells. Type V hypersensitivity reaction plays an important role in pathogenesis of Graves’ disease, in which thyroid hormones are produced in excess quantity. It is postulated that long-act-ing thyroid-stimulating antibody, which is an autoantibody to thyroid membrane antigen, combines with thyroid-stim-ulating hormone (TSH) receptors on a thyroid cell surface. Interaction with TSH receptor produces an effect similar to the TSH, resulting in an excess production and secre-tion of thyroid hormone, which is responsible for Graves’ disease.
Table 19-4 summarizes important features of various types of hypersensitivity.