TCRbeta1/TCRbeta2 (TRBC1/TRBC2) antibody pair for determining T-cell monotypia as a surrogate for clonality in formalin-fixed paraffin-embedded material

AIM: T-cell lymphomas are often histologically indistinguishable from benign T-cell infiltrates. Clonality testing is frequently required for diagnosis. It lacks the spatial context and is slow and expensive, relying on complex multiplexed PCR reactions, interpreted by scientists or pathologists with specialist molecular training. We set out to make monoclonal antibodies to develop a novel immunohistochemical test for T-cell lymphoma, analogous to the kappa/lambda assay for B-cell and plasma cell neoplasms. METHODS: We developed a pair of highly specific monoclonal antibodies against the two alternatively used but very similar T-cell receptor β constant regions, TCRβ1 and TCRβ2 (encoded by the TRBC1 and TRBC2 gene segments). We demonstrate the feasibility of immunohistochemical detection of TCRβ1 and TCRβ2 in formalin-fixed, paraffin-embedded tissue as a novel diagnostic strategy for T-cell lymphomas. RESULTS: Single immunostaining results are presented for 13 T-cell lymphomas and 8 benign T-cell populations, together with illustrative examples of TCRβ1/2 double immunostaining. Finally, we show that this single immunostaining is amenable to automated cell counting, permitting accurate calculation of the TCRβ2:TCRβ1 ratio. CONCLUSION: This novel assay can be used in a similar way to the kappa/lambda assay for B-cell and plasma cell neoplasms.