Quantitative PCR detection of t(14;18) bcl-2/JH fusion sequences in follicular lymphoma patients: comparison of peripheral blood and bone marrow aspirate samples

Abstract

In patients with follicular lymphoma (FL), it is unresolved whether peripheral blood (PB) can replace bone marrow (BM) aspirate samples for detection of bcl-2/JH fusion sequences that result from the t(14;18)(q32;q21). We compare here the results of quantitative polymerase chain reaction (q-PCR) analysis for bcl-2/JH involving the major breakpoint cluster region (mbr) on paired PB and BM aspirate samples from 60 consecutive FL patients. There was a significant correlation between the level of bcl-2/JH fusion sequence obtained from PB and BM aspirate samples (r = 0.886), with 82% of samples showing less than one log of difference. Patients who had histological evidence of FL involving concurrent BM biopsy specimens had moderate to high levels of bcl-2/JH in both PB and BM aspirate samples, allowing unequivocal determination of translocation status (median bcl-2/JH to cyclophilin level was 8.014%). In contrast, patients with no detectable FL in their BM biopsy specimens often showed low levels of bcl-2/JH in both PB and BM aspirate samples (bcl-2/JH to cyclophilin median level = 0.006%), in a range similar to background levels that could be detected in patients without FL (n = 15, median bcl-2 mbr/JH to cyclophilin level = 0.002%). We conclude that PB can be used in place of BM aspirate samples to test for the presence of bcl-2 mbr/JH fusion sequence in FL patients and that either PB or BM aspirate testing yields a rough approximation of the degree of BM involvement by FL. However, in patients with minimal levels of bcl-2/JH in PB or BM aspirate samples, confirmation of this result by testing the primary tumor is recommended to confirm the presence of an identical bcl-2/JH fusion sequence and exclude false-positive results.

Figure 1

Correlation between normalized bcl-2 mbr/JH levels in paired bone marrow aspirate and peripheral blood samples. A: Levels among patients in which concurrent BM core biopsy was involved by lymphoma. B: Levels among patients in which bone marrow biopsy was not histologically involved.

Figure 2

Correlation between extent of follicular lymphoma present in bone marrow biopsy and level of normalized bcl-2 mbr/JH product in BM aspirate.

Figure 3

Comparing levels of bcl-2/JH product in bone marrow aspirate and peripheral samples in the 60 patients with mbr+ follicular lymphoma. A: Comparison of BM and PB bcl-2/JH levels seen in patients who had lymphoma detected in concurrent BM core biopsy. B: Comparison of BM and PB bcl-2/JH levels in patients who did not have lymphoma detected in concurrent BM core biopsy.