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

T-cell receptor antibodies (TCR alpha beta and TCR gamma delta) 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 TCR alpha beta population was predominant in all categories except T gamma 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 TCR gamma delta population. Natural killer cell lymphoma (NKL) showed essentially absence of either TCR alpha beta or TCR gamma delta 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 TCR beta gene rearrangement and one of two cases with TCR alpha gene rearrangement expressed TCR alpha beta protein. One of four cases with TCR gamma gene rearrangement and both cases with TCR delta gene rearrangement expressed TCR gamma delta protein. Thus, TCR antibody phenotyping can reliably predict TCR genotypes under most circumstances.