Diagnostic utility of isolated tube C positivity in T-cell receptor β testing using BioMED-2 primers

Abstract

Objectives: T-cell receptor (TCR) gene rearrangement studies are widely used for assessing T-cell clonality. The frequency and significance of clonal peaks restricted to TCR β (TCRB) tube C are uncertain. We retrospectively reviewed 80 TCR studies performed on bone marrow/ peripheral blood. Methods: TCRB and TCR γ (TCRG) analyses were performed using BIOMED-2 primers. A peak was considered clonal or atypical if it was reproducible and 5× or more or 3× to 5× polyclonal background, respectively. Results: TCRB analysis demonstrated 12 (15%) of 80 cases with one to four isolated peaks in tube C (>3×) with polyclonal pattern in tubes A and B. TCRG analysis was monoclonal in two cases (both definite T-cell neoplasms), polyclonal in four, and oligoclonal in six. Of the 10 cases without clone in TCRG, six had autoimmune disorder and none had T-cell neoplasm. Conclusions: Peaks restricted to TCRB tube C in the TCR analysis may be misleading, as it is often not indicative of an overt T-cell neoplasm.