A 17-year-old girl receives a tetanus booster immunization. Within 48 hours, she develops localized arm erythema (BP 118/76, HR 82, RR 16, Temp 38.2°C, SpO2 98%). Serum analysis shows elevated IgG titers with significantly higher affinity antibodies compared to her primary vaccination response five years prior. She denies fever or systemic symptoms. Which of the following processes most directly explains the increased antibody affinity observed during this secondary immune response?
- A)Random assortment of heavy and light chains during fetal development
- B)Activation of complement by immune complexes
- C)Somatic hypermutation and selection of B cells in germinal centersGABARITO
- D)Rearrangement of V, D, and J gene segments in thymocytes
- E)Negative selection of autoreactive T cells in the thymic medulla
Explicação
Affinity maturation occurs in germinal centers after antigen exposure, where activated B cells undergo somatic hypermutation and higher affinity clones are selected. Booster vaccination therefore produces antibodies that bind antigen more strongly than those m... Ver explicação completa e trilha adaptativa →