[PCR study of bcl-2 rearrangement in autologous transplantation of peripheral stem cells in follicular non-Hodgkin's lymphoma].

OBJECTIVE

To value the usefulness of the bcl-2 rearrangement analysis by PCR in the study of the minimal residual disease in patients with follicular non-Hodgkin's B cell lymphoma (NHL) submitted to peripheral blood stem-cell transplantation (PSCT).

PATIENTS AND METHOD

The study was done on 12 patients diagnosed with low grade B-cell NHL, who were entered in a program of myeloablative chemotherapy followed by rescue with progenitor cells obtained from peripheral blood. At the time of peripheral stem-cells (PSC) harvesting, 8 patients did not present medullar infiltration and four of them presented medullar infiltration according to conventional histological criteria. The study was done on DNA from samples taken from bone marrow and cells taken in the apheresis. The DNA samples were studied by PCR to determine the existence of the bcl-2 rearrangement.

RESULTS

At the time of apheresis, 8 patients did not present medullar infiltration according to conventional histological criteria but 7 of them presented bcl-2/JH rearrangement. Most patients studied (10 out of 12) showed bcl-2/JH rearrangement (minimal residual disease) in apheresis products. However, in 2 of these 10 patients, such rearrangement was negative in the bone marrow samples obtained 3-6 and 12 months after transplantation.

CONCLUSION

In some patients with follicular NHL submitted to PSCT, the bcl-2/JH rearrangement had negativized after transplantation, this implies that the tumoral cells present in apheresis products lost their clonogenic capacity and were not able to subsist in vivo and that the myeloablative polychemotherapy schedules are able to eradicate the t(14; 18) translocation bearing cells or, at least, to decrease their number in bone marrow to levels below those of PCR detection.