T-cell receptor expression in lymphoid neoplasms. A comparison of phenotypic expression and genotyping

T-cell receptor antibodies (TCRαβ and TCRγδ) were used for a flow cytometric study of 114 specimens of lymphoid neoplasms and normal controls in order to find out whether or not the expression of TCR proteins differs in between normal and neoplastic tissues. It was found that TCRαβ population was predominant in all categories except Tγ lymphoproliferative disorder (TGLD), T-cell lymphoblastic leukemia (T-ALL), and natural killer-like T- cell lymphoma (NKTL), in which three of 18, one of three, and two of two specimens, respectively, showed a predominant TCRγδ population. Natural killer cell lymphoma (NKL) showed essentially absence of either TCRαβ or TCRγδ protein. Therefore, TCR antibodies can be selectively used in cases of TGLD, T-ALL, and NKTL to substantiate their diagnoses. Furthermore, the absence of TCR protein is characteristic of NKL and helps to distinguish it from NKTL. Without the TCR antibodies, TCR gene analysis is sometimes needed to separate these two entities. When comparing with genotyping, 11 of 12 cases with TCRβ gene rearrangement and one of two cases with TCRα gene rearrangement expressed TCRαβ protein. One of four cases with TCRγ gene rearrangement and both cases with TCRδ gene rearrangement expressed TCRγδ protein. Thus, TCR antibody phenotyping can reliably predict TCR genotypes under most circumstances.