Age‐related impaired affinity maturation and differential D‐JH gene usage in human VH6‐expressing B lymphocytes from healthy individuals

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Abstract
To elucidate the basic molecular events underlying humoral immunity during ontogeny and senescence, we analyzed a panel of 179 polymerase chain reaction‐derived VH6‐D‐JH rearrangements from cord blood, peripheral blood, and spleen. Nucleotide sequence analysis of the CDR3 region shows that there is a difference in D and JH gene usage in functional rearrangements between lymphocytes from peripheral blood and spleen. Analysis of the VH6 gene shows that the mutational frequencies rise from 0.81% in cord blood to 1.96% in peripheral blood lymphocytes derived from young adults, and decrease to 0.80% in samples from individuals older than 50 years. The number of rearrangements carrying mutations follows a similar pattern: 22% in cord blood, 73% in the age group 20–49 years, and 57% in the age group over 50 years. The mutational frequencies among the mutated genes are, however, similar for cord blood and young adults, 2.76% and 2.51%, respectively, and 1.3% in older adults. These data show an age‐related impaired affinity maturation which might relate to the decrease in immunological responsiveness among the elderly.