T-cell type lymphoproliferative disease of granular lymphocytes (LDGL) is equipped with a phenotypic pattern typical of effector cytotoxic cells.

By analyzing the expression of several cytotoxic markers, killer-immunoglobulin-like receptors (KIRs), CD94/CD159, CD314 and natural cytotoxicity receptors (NCRs), in 22 CD3+ lymphoproliferative disease of granular lymphocyte (LDGL) patients we investigated whether granular lymphocytes (GLs) displayed the phenotype of fully differentiated cytotoxic cells. Our results demonstrate that GLs express a pattern consistent with fully differentiated CTLs. KIRs are expressed only in a fraction of patients (7/22), as is CD94/CD159 (5/22). In conclusion, GLs in CD3+ LDGL patients typically show the phenotype of fully differentiated CTL, whereas the expression of NK receptors does not represent a common feature of the proliferating clone.