Numbers between brackets are the nucleotide positions ofbcl-2 and J_H at crossover sites, based on the published sequences. (A) Sequencing analysis of t(14;18)/MBR-rearranged bands of OCI LY8 tumor showed a bcl-2/J_H junctional sequence corresponding to the previously known sequence of this cell line by our own previous experiments. The same DNA sequence was also obtained from two products of single cell PCR performed on OCI LY8 tumor tissue sections. (B) Two cases of HD-involved lymph nodes are studied by direct sequencing analysis of the bcl-2/J_H junctional region. In case 1, five PCR runs performed on the same DNA sample gave five rearranged bands of similar size. The sequence of the bcl-2/J_H junctional region of these five rearranged bands detected by gel electrophoresis was identical, thus confirming the clonal relationship of the t(14;18)-carrying cell population in the HD-affected lymph node, whereas case 2 gave bcl-2/J_H rearranged bands of different size from the five PCR runs performed on the same DNA sample. As expected, sequence analysis of the rearranged bands showed different bcl-2/J_H junctional region sequence (2 sequences [2a and 2b] from 2 PCR runs are given as an example), confirming the presence of different t(14;18)-bearing cell clones in the lymph node sample. (C) Two cases of reactive lymph nodes are studied by direct sequencing analysis of the bcl-2/J_H junctional region. The first case showed five rearranged bands of the same size and the second case gave five rearranged bands of different size in the five seminested PCR performed on the same DNA sample in each case. In case 1, DNA sequencing study of the bcl-2/J_H junctional region of the t(14;18)/MBR PCR amplification products demonstrated that only two of the five bands were clonally related (1a). The three other sequences were proven to be different (one sequence [1b] from 1 PCR run is given as an example). In the second case, the presence of a different bcl-2/J_H junctional region in each band confirmed the belonging of these bands to different cell population clones (2 sequences [2a and 2b] of 2 PCR runs are given as an example).