Evidence for subclone selection over time in FL 8 and FL 3.

(A) The IgM- and IgG-derived VH sequences from FL 8-'83 (8-'83μ and 8-'83γ, respectively) and from the relapse, 8-'92, are represented as lines. The consensus sequences had been determined by crude tissue analyses.10 The total number of somatic mutations compared with the germline gene, V3-23, is indicated at the end of each line. In addition, the IgM-derived sequences from microdissected samples (MD) 2, 3a, 3b, and 4a, as well as the IgG-derived sequences from samples 2 and 9a from FL 8-'83 are shown. The sample numbers represent the different follicles from which they were taken. Different samples from one follicle are designated with a different letter. Replacement and silent mutations are represented as closed and open circles, respectively. Codon numbers are indicated underneath the symbols. Only the mutations that differ between the sequences are indicated. The sequences depicted of the microdissected samples of FL 8-'83 had an identical mutation pattern and were remarkably similar to that of the consensus sequence of FL 8-'92. (B) Comparison of the consensus sequences of FL 3-'93 and 3-'95 (top and bottom line).10 Only the nucleotide differences between them are shown. The total number of mutations compared with the germline gene, V3-7, is indicated at the end of each line. A PCR was performed on cDNA of FL 3-'93 using primers (depicted as arrows) designed on the 3-'95–specific sequence in the indicated areas. The 3′ termini of these primers matched the critical 3-'95 positions in codons 2 and 96, respectively. The middle line depicts the sequence of the product obtained by this time point–specific PCR.