Figure 6

ILFs from young and aged mice contain a B-lymphocyte repertoire that is reflective of the systemic B lymphocyte pool; the B-lymphocyte repertoire becomes skewed with aging. RNA isolated from the spleen, PP, and individual ILFs from a young and aged mouse was transcribed into cDNA and immunoglobulin genes amplified using a universal V_H primer and a constant IgM region primer. Gel-purified products were ligated into vectors and individual clones containing the appropriate size insert were sequenced and assigned to a V_H family. Analysis of all clones identified from the young (left) and aged mice (right) revealed a similar preferential usage of V_H families with V_H1, V_H2, and V_H14 representing greater than 80% of the VH families used by either mouse (panel a). With aging, the Ig repertoire became more skewed with dominant usage of the V_H1 family (panel a right). Comparison of the V_H usage within the spleen (panel b), reflective of the systemic pool, to the PP (panel c) and individual ILFs (panel d) revealed similar V_H usage between these tissues within aged and young mice and revealed that the Ig repertoire was skewed toward dominant V_H1 usage in all tissues in the aged mouse (panels b-d right).