T-CELL RECEPTOR EXPRESSION IN LYMPHOID NEOPLASMS - A COMPARISON OF PHENOTYPIC-EXPRESSION AND GENOTYPING

T-cell receptor antibodies (TCRalphabeta and TCRgammadelta) 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 TCRalphabeta population was predominant in all categories except Tgamma lymphoproliferative disorder (TGLD), T-cell lymphoblasti c leukemia (T-ALL), and natural killer-like T-cell lymphoma (NKTL), in which three of 18, one of three, and two of two specimens, respective ly, showed a predominant TCRgammadelta population. Natural killer cell lymphoma (NKL) showed essentially absence of either TCRalphabeta or T CRgammadelta protein. Therefore, TCR antibodies can be selectively use d in cases of TGLD, T-ALL, and NKTL to substantiate their diagnoses. F urthermore, the absence of TCR protein is characteristic of NKL and he lps to distinguish it from NKTL. Without the TCR antibodies, TCR gene analysis is sometimes needed to separate these two entities. When comp aring with genotyping, 11 of 12 cases with TCRbeta gene rearrangement and one of two cases with TCRalpha gene rearrangement expressed TCRalp habeta protein. One of four cases with TCRgamma gene rearrangement and both cases with TCRdelta gene rearrangement expressed TCRgammadelta p rotein. Thus, TCR antibody phenotyping can reliably predict TCR genoty pes under most circumstances.