Leukemic CD3(+) LGL share functional properties with their CD8(+)CD57(+) cell counterpart expanded after BMT

Leukemic T-LGL (large granular lymphocyte) composed of clonal CD3(+)TCR alp ha beta(+)CD8(+)CD57(+) cells were compared with oligoclonally CD3(+)CD8(+) CD57(-) lymphocytes expanded after BMT. Leukemic CD3(+)CD8(hl+)CD57(+) LGL showed several phenotypic differences such as an upregulation of CD16 and a dhesion molecules (mainly CD11c, CD58 and CD54), activation markers and an exclusive CD45RA isoform expression. Unstimulated CD3(+)CD8(+)CD57(+) LGL f rom both leukemic and BMT donors spontaneously developed an ex vivo CTL-lik e CD3-redirected cytotoxicity but no NK cell activity. Different stimuli (P HA, PMA or rhlL-2) induced similar cytotoxic profiles after a 6-day culture involving a CD3-redirected lysis predominating over a low NK cell activity . However, culture of leukemic LGL with these stimuli allowed either a 2 we ek persistence (PMA or rhlL-2) of CD8(+)CD57(+) LGL or their disappearance after 3 days (PHA). Furthermore, leukemic CD8(hl+)CD57(+) T lymphocytes pro duced an inhibitor of cytotoxic functions as previously described for BMT r ecipients' CD8+CD57+ cells. Thus, despite some phenotypic differences betwe en both cell sources, leukemic CD57(+) T-LGL display the same functional ch aracteristics of cytotoxic effector and immunoregulatory T cells as CD8(+)C D57(+) T cells from BMT recipients which might represent their normal count erpart.