Normal adaptive immune responses include cell-mediated immunity against intracellular invading organisms and antibody (humoral) immunity against extracellular organisms. However, autoimmune disease, tissue damage, inappropriate inflammation, and amyloidosis can result when the adaptive immune system responds excessively. These hypersensitivities are classified into four different types of reactions. Anaphylactic reactions are classified as which of the following types of hypersensitivities?