Clonal expansion of gamma delta T cells expressing two distinct T-cell receptors.

92% of peripheral blood mononuclear cells from a patient with chronic lymphocytosis (WBC 22 x 10(9)/l) were recognized by pan-gamma delta monoclonal antibody (mAb) TCR delta 1. Further analysis with anti-V gamma/V delta mAb indicated that the expanded gamma delta T-cell population was stained by mAb specific for V gamma 2/3/4, V gamma 5 and V delta 1 but not mAb specific for V gamma 8, V gamma 9, V delta 2 or V delta 3. Cloning and sequencing of reverse transcription PCR products revealed the presence of V gamma 4, V gamma 5 and V delta 1 in-frame transcripts. All the cDNA clones obtained from each of these variable elements had identical junction regions, thus clearly demonstrating clonality. As far as we know, this is the first description of a pathological clonal expansion of gamma delta T cells with two distinct surface-expressed T-cell receptor molecules.