EBV and Granular Lymphocytes Proliferation

Abstract

Large granular lymphocytes, which are characterised by the presence of azurophilic granules in their cytoplasm, are the principle effectors of natural killer (NK) function and antibody-dependent cell-mediated cytotoxicity, and are involved in the protection of the host against infections and tumor growth. Recently, an increasing number of patients with lymphoproliferative disease of granular lymphocytes (LDGL) have been reported (1,2). As already indicated LDGL is a heterogeneous disorder in terms of the cell lineage, clinical features, and clonal nature. Phenotypically, LDGL can be divided into two major subgroups: CD3+LDGL (T-lineage) and CD3-LDGL (NK-lineage). Clinically, most patients exibit an indolent course, but some an aggressive or a chronic to progressive course. The clonal nature of LDGL has been established in some but not all cases of LDGL on the basis of T-cell receptor gene (TCR) rearrangement and karyotype analyses. Although the pathogenesis of LDGL is likely to be complex, so far more than half of the cases were classified as primary LDGL. More recently we suggested the possibility of an etiologic link between EBV infection and some instances of LDGL with a CD3-phenotype (3). To clarify this issue we have looked at EBV genome by Southern blot analysis of DNA obtained from the peripheral blood of 23 patients with LDGL, including five with chronic active EBV (CAEBV) infection.