Malignant lymphoma originating from the earliest T-lineage precursor cell.

The earliest T-lineage precursor cells with a CD3-CD4+CD8- phenotype and germline-state T-cell receptor (TCR) genes have recently been identified in the murine thymus. We report a case of malignant lymphoma that was considered to originate from the human counterpart of this newly defined murine T-cell population. The surface phenotype of the lymphoma cells was CD2+CD3-CD4+CD8-CD25-CD34-CD44+HLA-DR+. TCR-beta, -gamma, -delta chain genes and immunoglobulin heavy and light chain genes were all in a germline state. These characteristics were markedly similar to those of the murine earliest T-lineage precursor cells. The present case thus strongly suggests the presence of the human counterpart of this novel murine T-cell population.