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.

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