Large Granular Lymphocytes From Patients With Expanded LGL Populations Acquire Cytotoxic Functions and Release Lymphokines Upon In Vitro Activation

The phenotypic and functional features of purified large granular lymphocytes (LGL) from ten patients with LGL population expansions and cytopenias are described. The predominant LGL phenotypes were T3 +, T8+, Leu-1 1 + I-; however, in two patients. LGL expressed a T3-, Leu-1 1 + phenotype. Variable combinations of other LGL markers (OKM1, Leu-7), and HLA-DR were detected in individual cases. In nine of ten cases, freshly isolated LGL did not exert cytolytic activity for K562 target cells, but purified LGL cultured in the presence of recombinant L ARGE GRANULAR LYMPHOCYTES (LGL) are a subset of lymphoid cells defined by morphologic and cytochemical criteria.’3 These cells display abundant cyto-plasmic azurophilic granules that stain with the cytochemi-cal reactions for lysosomal acid hydrolases but are peroxi