ACAAI Review for the Allergy & Immunology Boards All Chapters Questions and Answers | Verified

Small-molecule antigen requires covalent linkage to a larger carrier to stimulate adaptive immune response. The process is achieved in collaboration between hapten-specific B cells and carrier-specific T cells. This is the basis of developing conjugated vaccines. - What is the hapten-carrier effect? SEB and SEC from Staphylococcus aureus cause food poisoning. TSST from Staphylococcus aureus and SPE-C from Streptococus pyogenes cause toxic shock syndrome. - What are the common superantigens and related diseases? Natural killer T (NKT) cells recognize lipid antigens, and the CD1 molecule is involved. - Which type of T cell recognizes lipid antigens and what molecule is involved? Protein antigens are T-cell dependent. Polysaccharide, nucleic acid, and lipids are T-cell independent. - Which antigens are T-cell dependent and which are T-cell independent? On the MHC class I molecule, α3 is the binding site for CD8. On the MHC class II molecule, β2 is the binding site for CD4 - What is the binding site for CD4 on the MHC class I molecule? What is the binding site for CD8 on the MHC class II molecule? On the MHC Class I molecule, α1 and α2 make up the peptide binding cleft. On the MHC class II molecule, α1 and β1 make up the peptide binding cleft. - Which chain makes up the peptide binding cleft in MHC class I molecules? Which chain makes up the peptide binding cleft in MHC class II molecules? An MHC class I molecule presents both intracellular antigens (e.g., viral antigen in cytoplasm) and extracellular antigens (via cross-presentation). The loading site is endoplasmic reticulum (ER). - MHC class I molecule presents which type of antigens and where does the antigen-MHC class I loading happen? The MHC class II locus. They are involved in peptide processing for MHC class I however. - In which chromosomal region are the TAP proteins located? The MHC class II molecule presents extracellular antigens (e.g., antigens from phagocytosed bacteria). The loading site is phagolysosome. - MHC class II molecule presents which type of antigen? Where does the antigen-MHC class II loading happen? IL-10 and TGFβ - Which cytokines are important for Tregs? TCR, MHC molecules, CD4, CD8, CD19, B7-1, B7-2, Fc receptors, KIR, and VCAM-1 - What molecules belong to the Ig superfamily? Junctional diversity; TdT enzyme is important in this process. - Which somatic recombination process introduces the greatest diversity in immune receptors and which enzyme is important in this process? The FcRn receptor binds to IgG and allows it to be endocytosed. It protects it from the lysosome and instead recycles it to the cell surface. This accounts for the long half-life of IgG in humans. This is also the mechanism by which IgG is transported across the placenta and fetal intestine. IgG3 has the shortest half-life because it poorly binds to FcRn. - What is the role of the FcRn receptor? X-linked lymphoproliferative syndrome (XLP) - Mutation in SAP causes which disease? Cyclosporine binds to cyclophilin, which are proteins also called immunophilins. The drug-protein complex inhibits calcineurin and therefore NFAT translocation to the nucleus. - Immunosuppressant cyclosporine binds to which molecule in T-cell signaling pathway? CD21, CD19, and CD81 - What CD molecules are in the BCR coreceptor? CXCR4 - Which chemokine receptor is associated with WHIM (warts, hypogammaglobulinemia, infections, amd myelokathexis) syndrome? α4β7 - Which integrin molecule is important for gut homing by binding to MAdCAM? 4-10 days - Upon first exposure to a medication, when might a patient develop symptoms of serum sickness? IL-4 Rα, which is targeted by dupilumab - Which component is shared by IL-4 and IL-13 receptors? IFNγ receptor deficiency results in susceptibility to Mycobacterium tuberculosis and other intracellular bacteria. - What is the result of IFNγ receptor deficiency? IL-1β - What interleukin is excessively produced in cryopyrinopathies? Lipopolysaccharide responsive beige-like anchor protein (LRBA) deficiency - What disease presents with early onset hypogammaglobulinemia with autoimmunity and immune dysregulation? It maintains intracellular stores of CTLA4, which can stop T-cell activation. - What is the function of LRBA? Properidin - Which complement deficiency is inherited as X-linked? CD 59 and S protein - What two molecules inhibit MAC formation? CD 55 and CD 59 - Which complement receptor is implicated in PNH (paroxysmal nocturnal hemoglobinuria)? Adipose tissue - What is the main source of Factor D? HUVS (hypocomplementemic urticarial vasculitis) - Anti-C1q antibody is found in which disease process? Factor XII - Contact activation pathway is initiated by which factor? B-2 receptor - Bradykinin acts on what receptor on endothelial cells? IgG and IgM - What are the primary immunoglobulins involved with type II hypersensitivity? Classical pathway - IgG and IgM activate which complement pathway? Both are type III hypersensitivity reactions; however, serum sickness is systemic and arthus reaction is local - How are serum sickness and arthus reaction similar and different? Innate immunity and adaptive immunity - Complement activation is involved with what types of immunity?