Adaptive Immunity — Humoral (B Cells & Antibodies)

By completing this question set, you will be able to describe immunoglobulin structure and explain how the variable and constant regions determine antigen specificity and effector function, respectively. You will trace V(D)J recombination and identify the four mechanisms that generate antibody diversity from a limited number of germline genes. You will distinguish T-dependent from T-independent B-cell activation, explain why CD40-CD40L interaction is essential for class switching and germinal center formation, and predict the consequences of its absence (Hyper-IgM syndrome). You will describe germinal center reactions including somatic hypermutation, affinity maturation, and class switch recombination, and identify AID as the enzyme critical to both processes. You will differentiate the five immunoglobulin classes by structure, location, and effector function, and predict which isotype is most relevant in a given clinical scenario. You will compare primary and secondary immune responses and explain how serologic patterns (IgM vs IgG) inform clinical diagnosis. Finally, you will classify vaccine types by mechanism, explain why conjugate vaccines are necessary for children under 2 years, distinguish active from passive immunization, and apply contraindication rules to immunocompromised and pregnant patients.