Large granular lymphocyte leukaemia is characterized by a clonal T-cell receptor rearrangement in both memory and effector CD8(+) lymphocyte populations

Abstract

Large granular lymphocyte (LGL) leukaemia is a disease with increased numbers of circulating granular lymphocytes and an increased percentage of clonally rearranged CD8(+)CD57(+) cells. To determine whether LGL cells are also found in other lymphocyte subsets, CD8(+) cells from 10 LGL patients were sorted into CD57(+) and CD57(-) fractions and analysed for clonality using a T-cell receptor gamma (TCR gamma) polymerase chain reaction (PCR). In nine patients, a clonal TCR rearrangement was identified in the CD8(+)CD57(+) cells, and in one patient, the TCR rearrangement was oligoclonal in the CD8(+)CD57(+) fraction. In eight out of nine of the clonally rearranged patients, the same band was also present in the CD8(+)CD57(-) fraction. To define the relationship between CD57(-) and CD57(+) LGL populations, CD8(+)CD57(-) and CD8(+)CD57(+) cells were sorted from five patients and cultured in the presence of anti-CD3 plus CD28 antibodies. The CD57(+) cells died of apoptosis before d 7, while the CD57(-) cells proliferated and differentiated into CD57(+) cells. Clonal analysis identified the same band in both cultured subpopulations and in the uncultured CD8(+) cells. Immunophenotypical analysis showed that CD8(+)CD57(-) cells expressed memory cell markers, while the CD8(+)CD57(+) cells exhibited effector characteristics. These results suggest that LGL disease originates in a CD57(-) memory T-cell compartment that continually generates CD57(+) (effector cell) progeny.