Correlation between SHM and dual expression of CD69 and CD45RO. (A) GC B cells from Tonsil 76 were costained with anti-RO and anti-CD69 and sorted into 6 resultant subsets. N values are listed for IgM: CD69−RO− (13), CD69−RO+ (20), CD69+RO− (18), and CD69+RO+ (21); and IgG: CD69−RO− (38), CD69−RO+ (38), CD69+RO− (33), and CD69+RO+ (25). (B) AID transcripts were semiquantitatively amplified (as in Figure 2B) from each of the above RO/CD69 fractions, including CD69+RO+/− (CD69−RO+/− cells were not collected). β-actin amplification was used to normalize RNA levels. Molecular weight markers are indicated to the left.