TY - CHAP M1 - Book, Section TI - Hypersensitivity (Allergy) A1 - Levinson, Warren A1 - Chin-Hong, Peter A1 - Joyce, Elizabeth A. A1 - Nussbaum, Jesse A1 - Schwartz, Brian PY - 2020 T2 - Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 16e AB - Hypersensitivity reactions are exaggerated or inappropriate immune responses to benign antigens. It is the immune response, not the antigens, which are harmful to the host. Usually, hypersensitivity reactions occur in response to external stimuli (antigens), whereas autoimmune reactions (see Chapter 66) occur in response to internal stimuli (antigens). The term allergy is often equated with hypersensitivity but more accurately should be limited to the immunoglobulin (Ig) E-mediated reactions discussed later in the section “Type I: Immediate (Anaphylactic) Hypersensitivity.” Note that many autoimmune diseases have pathologic features of one or more hypersensitivity reactions. This chapter will cover the patterns of hypersensitivity reactions using examples of diseases in which there are known external triggers. Chapter 66 will cover autoimmune diseases, in which the immune reactions are largely against are self-antigen(s). SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/04/17 UR - accessmedicine.mhmedical.com/content.aspx?aid=1175827237 ER -