Significance of BIOMED-2 standardized IG/TCR gene rearrangement detection in paraffin-embedded section in lymphoma diagnosis

Abstract

To explore the feasibility of detecting lymphoma with the application of BIOMED-2 standardized immunoglobulin/T cell receptor (IG/TCR) gene rearrangement system in formalin fixed paraffin-embedded (FFPE) tissue samples, and to discuss the relationship between the longest amplification fragment of extracted DNA and positive detection rate of different IGH V-J primers. DNA was extracted from 50 cases of FFPE tissue samples. Multiplex-PCR amplifications were performed and then the IG/TCR gene rearrangements were analyzed using BIOMED-2 standardized clonality analysis system. (1)When the DNA concentration was diluted to 50-100 ng/μl from 100-500 ng/μl, the proportion of the longest amplification fragment (300-400 bp) of DNA was improved from 10.0% to 90.0% in 30 cases of diffuse large B cell lymphoma (DLBCL) wax roll samples (P<0.01). The positive rate of IGH+IGK was increased from 46.7% to 83.3%, the difference was statistically significant (P=0.006). The lengths of the longest amplification fragments of DNA were all longer than 300 bp in the paraffin section samples of DLBCL. The positive rate of IGH+IGK of these samples was 96.7%. The difference of the positive rate of IGH+IGK between the wax roll samples and the paraffin section samples had no statistical significance (P=0.195). (2)When the concentration of DNA was high, most of the longest amplification fragments of extracted DNA were 100 bp or 200 bp, and the detection rate of short fragment IGH FR3 was more stable than that of long fragment IGH FR1. (3)The clonality analysis of TCRG+TCRB in all 13 cases of peripheral T cell lymphoma samples showed positive results, while no positive IG/TCR clones were found in 7 cases of reactive lymphoid tissue hyperplasia in control group. Dilution of DNA is the only method to improve not only the proportion of longest fragment amplification but also the detection rate of clonality. The detection rate of IGH FR3 would not be affected by the concentration of DNA. The application of BIOMED-2 standardized IG/TCR gene rearrangement system in FFPE tissue samples plays an important role in the lymphoma diagnosis.