The following glossary defines the Immunotoxic Effects

1. HYPERSENSITIVITY: increased reactivity to an antigen to which a person (or animal) has been previously exposed, with an adverse rather than protective effect; sometimes used as a synonym for allergy. This Guidance includes only Type I (anaphylactic) reactions, which are mediated by IgE antibodies, and Type IV (delayed hypersensitivity) reactions mediated by T lymphocytes because they are the most common. Type I reactions also are the most serious. Type II and Type III reactions involve antibodies (IgG or IgM, but not IgE) and complement, but are relatively rare and are less likely to occur with medical devices/materials.
2. CHRONIC INFLAMMATION: Inflammation is the normal tissue response to local injury. Acute inflammation is relatively short-lived (days) and characterized by neutrophils as the primary cellular infiltrate. In contrast, chronic inflammation can last up to months or longer, and is characterized by infiltration of macrophages and lymphocytes. Chronic inflammation may lead to immune granuloma formation and more serious immunological consequences, such as autoimmune disease.
3. IMMUNOSUPPRESSION: Inhibition of the adaptive immune response (i.e. antibody and T cell responses); one potential consequence is more frequent and serious infections resulting from reduced host defense.
4. IMMMUNOSTIMULATION: Unintended or inappropriate antigen-specific or non-specific activation of the immune system. For this guidance, immunostimulation includes a.) unintended immunogenicity of biomaterials (e.g. antibody and/or cellular immune response to a foreign protein), and b.) adjuvancy, enhancement of the immune response to an antigen by a material with which it is mixed ex vivo or in situ.
5. AUTOIMMUNITY: Immune response to the body’s own constituents (autoantigens). An autoimmune response, indicated by the presence of autoantibodies or T lymphocytes reactive with host tissue or cell antigens, may (but not necessarily) result in autoimmune disease with chronic, debilitating, and sometimes life-threatening tissue and organ injury. In some cases, the specific autoantigens may not be characterized or known.