Abbas: Cellular and Molecular Immunology, 9th Edition Antibodies and Antigens Test Bank

Questions 1-5 Match each of the descriptions in questions 1-5 with the correct lettered antibody isotype (A-E). (Answers may be used more than once.) A. IgA B. IgD C. IgE D. IgG E. IgM 1. The secreted form of this isotype forms pentamers around a J chain ANS: E. IgM is secreted as a J chain–linked pentamer. 2. The most abundant Ig isotype in the blood ANS: D. The blood IgG concentration is about 3.5mg/ml and includes four subtypes (IgG1 to IgG4). 3. The isotype only found in membrane-bound form on naive B cells ANS: B. Very little IgD is secreted, and in membrane form is only on the surface of naive B cells. Its function is not well understood. 4. The isotype found predominantly in mucosal secretions ANS: A. IgA accounts for almost two thirds of the 3 g of antibody produced each day by an adult, most of which is produced in the gastrointestinal associated lymphoid tissues and secreted into the gut lumen. 5. The isotype most closely associated with immediate hypersensitivity (allergic) disease ANS: C. Most IgE that is secreted is bound to mast cells, and it plays a role in the activation of mast cells during allergic reactions. Questions 6-10 Match each description in questions 6-10 with the appropriate lettered term (A-I). A. Conformational determinant This study source was downloaded by from CourseH on :48:31 GMT -05:00 Cellular and Molecular Immunology 9th Edition Abbas Test Bank Test Bank 2 B. Linear determinant C. Neoantigenic determinant D. Hinge region E. Immun complex F. Fab G. Fc H. Tail piece I. Hapten 6. A proteolytic fragment of an antibody molecule that contains an intact antigenbinding site ANS: F. Fab fragments, derived from enzymatic cleavage of Ig molecules, are composed of one intact light chain covalently linked to the N-terminal region of one heavy chain and include a single intact antigen-binding site. 7. A three-dimensional shape, formed by a portion of a macromolecule, to which an antibody binds ANS: A. Conformational determinants will usually be destroyed by physicochemical disruption of macromolecules, such as by denaturation or proteolysis of proteins. 8. A small chemical group recognized by an antibody that is attached to a larger macromolecule ANS: I. Although haptens can be recognized by antibodies, they are not, by themselves, able to stimulate an antibody response (i.e., they are not immunogens). Antibody responses to haptens can be induced when the hapten is attached to a macromolecule, called a carrier. 9. The proteolytic fragment of an antibody molecule that contains the heavy chain constant region ANS: G. The Fc fragment, generated by proteolytic cleavage of an antibody molecule, is composed of the C-terminal end of the heavy chain and lacks the antigen-binding region. This region of an intact Ig molecule, which can interact with Ig receptors and complement, is called the Fc region. 10. A region of an antibody molecule that permits bivalent binding of antibodies to pairs of surface epitopes varying in distance from one another ANS: D. The hinge region, located between the two N-terminal Ig domains of the heavy chains of most isotypes, is flexible, permitting variations in the distance between the two antigen-binding sites. This study source was downloaded by from CourseH on :48:31 GMT -05:00 Cellular and Molecular Immunology 9th Edition Abbas Test Bank Abbas: Cellular and Molecular Immunology, 9th Edition Effector Mechanisms of Humoral Immunity Test Bank Matching Questions 1-4 For each of the following descriptions in questions 1-4, select the Fc receptor (A-G) that best matches it. A. FcRI (CD64) B. FcRIIB (CD32) C. FcRIIIA (CD16) D. FcRI E. FcRII (CD23) F. FcR (CD89) G. FcRn 1. High-affinity Ig receptor on mast cells important in immediate hypersensitivity reactions ANS: D. FcRI is a high affinity IgE receptor expressed on mast cells and basophils. Although serum IgE levels are are relatively very low, FOcMR1 receptors are fully occupied by IgE due to the high affinity of the receptor. Cross-linking of this receptor by allergen binding to the IgE leads to mast cell activation, which includes granule exocytosis with release of mediators such as histamine, as well as production of lipid mediators and cytokines. 2. High-affinity Ig receptor on macrophages and neutrophils important for phagocytosis and activation ANS: A. FcRI (CD64) is a high-affinity IgG1 and IgG3 receptor that mediates phagocytosis of opsonized organisms and delivers signals that enhance microbicidal activity of the phagocytes. 3. Low-affinity Ig receptor on natural killer cells that mediates antibody-dependent cellmediated cytotoxicity ANS: C. FcRIIIA (CD16) is a low-affinity IgG receptor that targets natural killer (NK) cells to bind and destroy IgG-opsonized target cells and signals the NK cell to release cytotoxic granules. 4. Ig receptor on B cells that mediates feedback inhibition ANS: B. FcRIIB (CD32) is a low-affinity IgG receptor expressed on B lymphocytes. When antigen-IgG complexes simultaneously bind to membrane Ig and to FcRIIB,