| Summary: | We have examined at the molecular level the CDR3 and adjacent regions in peripheral blood B lymphocytes ofnormal individuals. A total of 111 sequences (12-28 sequences from six individuals) were obtained after cloning of the polymerase chain reaction-amplified segments into plasmids or phage. The average length of the VDJ joining was 109 nucleotides, with a range from 79 to 151. Approximately 75 % of the sequences were in frame when translated into amino acids. Among the JH segments, J H4 was found most frequently (in 52.5 % of the sequences), and JH 1 and JH 2 segments the least frequently (-I % of the clones). A polymorphic JH6 gene with a one-codnn deletion accompanied by a base change was present in two of six patients. Preferential breakpoints were found for JH 2, J.3, J 4, and Jx5, although the breakpoints of JH6 were distributed more heterogenously. In-90 % of the cases, significant homology of the D regions with published D sequences was found. Preferential usage of a particular coding frame was observed in in-frame sequences utilizing DA, D21/9, and DMl segments. However, in general, all coding frames of germline D genes were used to generate CDR3s. Eight sequences that have a DN1-like D sequence with two base changes at the same positions were identified, suggesting the likely existence of a new
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