Characterization of γδ T cells in peripheral blood from patients with B-cell chronic lymphocytic leukaemia

Circulating gamma delta T cell populations in B-cell chronic lymphocytic leukaemia (B-CLL) patients were analysed. General lymphocyte immunotyping and T-cell receptor (TCR) diversity assays were performed by two-colour immunofluorescence measurement on a Coulter Cytofluograf system (EPICS). Different anti-TCR V gamma and V delta region mAbs were used. Additionally some molecular analyses were made for preliminary characterization of the S-chain rearrangement and the junctional sequence repertoire of V delta 1 T cell clones from B-CLL patients. All results were compared with those obtained with specimens from healthy donors. The relative number of gamma delta T cells in most B-CLL samples was significantly higher than in the controls (11.4 and 4.7%, respectively). Leukaemic patients, in several cases, showed an increased proportion of V delta 1-J delta 1 T lymphocytes. They were also the most abundant subfraction in peripheral blood of healthy donors, but that observation is controversial. Nucleotide sequence examinations of PCR amplified V delta 1-J delta 1 transcripts of enlarged T cell subsets from B-CLL patients revealed extensive junctional diversity of the rearranged gene region. Results suggest that the gamma delta T cell proliferation (most likely the V delta 1 subfraction) in the majority of B-CLL donors may reflect the specific response of gamma delta T lymphocytes against autologous tumour cells. The multiple clonal gamma delta T cell expansions may be derived in vivo from B-CLL tumour-associated antigen stimulation. The nature of that antigenic ligand is unknown. The correlation of leukaemic patient status with TCR molecular structure indicated non-significant dependence.