Why does repeated exposure to a pathogen, through vaccination or natural infection, result in antibodies with higher affinity?

💡 Explanation

Antibody affinity increases due to somatic hypermutation and clonal selection in germinal centers. Because B cells with higher affinity antibodies bind antigen more effectively, they outcompete others for T cell help and survival signals. Therefore, these selected B cells proliferate, rather than those with lower affinity.

• If a patient's thyroid hormone (T4) production increases rapidly due to a thyroid adenoma, which consequence follows concerning the hypothalamic-pituitary-thyroid (HPT) axis feedback loops?
• Why does close reading become difficult for individuals with presbyopia as the ciliary muscles weaken?
• A patient reports chronic pain despite no apparent tissue damage. If descending modulatory pathways from the brainstem are impaired, which consequence follows regarding substance P?
• A patient undergoing chemotherapy experiences severe neutropenia. If granulocyte colony-stimulating factor (G-CSF) is administered, which consequence follows concerning their immune response?
• Which effect results when a mutation disrupts the enzyme tetrahydrofolate reductase in the folate metabolic pathway?
• Which outcome occurs when beta-adrenergic receptors downregulate in cardiomyocytes?