Differences in T-cell-receptor gene rearrangement and transcription in nasal lymphomas of natural killer and T-cell types: implications on cellular origin.

Although nasal lymphomas showing midfacial destructive lesions had been classified as T-cell lymphomas, their exact cellular origin is still unclear. Although they usually express a restricted number of T-cell-related antigens, namely, CD2, CD43, and CD45RO, other pan-T or subset-T-lineage antigens, such as CD3 (membrane), CD5, CD4, CD8, and CD7, are frequently absent. Conversely, they often express a natural killer (NK) cell-associated antigen, CD56, but lack other mature NK markets. To study their cellular origin further, the authors analyzed T-cell receptor (TCR) gene transcription in three cases of nasal lymphomas and correlated the findings with the phenotype and gene rearrangement data. Two cases of nasal lymphomas with CD2+CD3(Leu4)-CD19-CD56+ phenotype were shown to express truncated 1.0-kb Tbeta and multiple unrearranged Tdelta transcripts with germline TCR beta, gamma, delta, and immunoglobulin heavy-chain joining region (JH) genes, consistent with NK cell lineage. In contrast, one case of nasal lymphoma with CD2+CD3(Leu4)+CD8+CD19-CD56+ phenotype expressed full-length Talpha, Tbeta, and Tgamma transcripts rearranged TCR beta, gamma, and deleted TCR delta genes, indicating T-lineage, These results support the view that nasal lymphomas can separated into NK-cell and T-cell neoplasms, based on differences genotypic characteristics. The possibility of these tumors being derived from a putative common precursor cell merits further investigation.