Expression of CD94/NKG2A and killer immunoglobulin-like receptors in NK cells and a subset of extranodal cytotoxic T-cell lymphomas.

Thirty-two natural killer (NK) and cytotoxic T-cell lymphomas and 14 noncytotoxic nodal T-cell lymphoma controls were immunostained with the use of monoclonal antibodies reactive against NK-cell receptor (NKR) molecules (CD94, NKG2A, p58.2, p58.1, p140, p70, p50.3). All NK-cell lymphomas (4 nasal/oral and 1 intestinal) expressed at least 1 NKR, the CD94/NKG2A complex. Two were positive for 1 or more killer immunoglobulin-like receptors. Of 15 extranodal cytotoxic T-cell lymphomas, 3 expressed CD94, including 2 intestinal and 1 hepatosplenic gammadelta T-cell lymphomas. In contrast, none of the nodal lymphomas were positive. Detection of NKRs may provide a useful tool to confirm the diagnosis of NK-cell lymphomas and to delineate a subgroup of cytotoxic T-cell lymphomas. Expression of NKRs only in extranodal cytotoxic T-cell lymphomas might reflect differences in the homing capabilities of cytotoxic T cells expressing NKRs in normal individuals and might be influenced in part by localized chronic immune reactions.