Determination of VH Family Usage in B Cell Lymphoma by BIOMED-2 IgH Clonality Assay
Frank Kuo, Linus Kuo. Brigham and Women's Hospital, Boston, MA; Pomona College, Claremont, CA
Background: Several different types of B cell neoplasms have exhibited biased VH family usage. The clinical significance of such bias is not clear partially because determination of VH family usage is not part of routine diagnostic work-up B cell lymphomas and analysis on large number of patients have been lacking. We set out to explore the possibility of using the widely used BIOMED-2 IgH clonality assay to determine VH family usage. If successful, VH family usage could become part of routine clinical practice.
Design: Analysis of the design of BIOMED-2 IgH clonality assay shows that different VH-family members present in a clonal rearrangement can be predicted to produce PCR fragments of specific sizes in the three BIOMED-2 reactions using different framework primers. The PCR peak sizes of 70 samples with clonal B cell rearrangement detected by BIOMED-2 IgH clonality assay were used to assign VH family usage based on our prediction. VH-family specific PCR assays were used to determine the actual VH family usage. The assigned usage and the actual usage were compared to determine the accuracy of the assignment.
Results: Of the 70 samples with clonal peaks in all three framework PCR reactions, we successfully assigned IgH VH family usage by their PCR peak sizes in 63 samples (90%) with our prediction method. We could not assign VH usage in 7 samples ecause the sizes of the PCR clonal peaks do not conform to prediction for any VH family, most likely due to insertion or deletion in the VH segments. The actual VH family usage was determined by VH family specific PCR reactions in the 63 samples. Comparison of the actual VH family usage with our assignment showed concordance in 58 of 63 specimens (92%).
Conclusions: BIOMED-2 IgH clonality assay can be used to assign VH family usage in a high percentage (>90%) of cases when each of the three framework reactions produces a clonal peak. Because the assignment requires only analysis of data already collected during routine diagnostic work-up, there is very little added cost and can be incorporated easily by any laboratory that already performs this test. The availability of VH family usage information for large number of B cell lymphomas and their clinical characteristic may help to understand the significance of VH family usage in these tumors. A free, public web page has been created to make the analysis widely available.
Tuesday, March 5, 2013 9:30 AM
Poster Session III # 186, Tuesday Morning