Ultrastructural morphology of granular lymphocytes (GL) from patients with immunophenotypically homogeneous expansions of GL populations (GLE).

We studied the morphology of large granular lymphocytes (GL) from 19 patients with expanded populations of GL (GLE) of homogeneous surface immunophenotype. By definition, all patients had increased numbers of medium-sized lymphocytes with azurophilic granules, and neutropenia, thrombocytopenia, and/or anemia. In all cases, the GL had an extended Golgi apparatus and prominent centrioles. Among cells from individual patients, the GL were homogeneous with respect to their granule morphology. GL containing parallel tubular arrays (PTA), commonly associated with GLE, were observed in 9 of 19 cases; granules containing scarce matrix with or without associated vesicles (SMG) were present in the remaining 10 cases. In all cases in which the cells had PTA, there was co-expression of CD3 and CD8, the T suppressor cell-associated phenotype, whereas only 4 of 10 cases with SMG expressed CD3 and CD8 (p less than 0.01, chi-square test). We conclude that the morphologic homogeneity of GL in individual patients with GLE differs significantly from the heteromorphism usually seen in reactive GL, and is consistent with, but not diagnostic of, a clonal proliferation of GL in persistent GLE.