Cytokine Expression in Large Cell Lymphoma Associated with Acquired Immunodeficiency Syndrome

Abstract

Cytokine expression was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in a retrospective sampling of 16 AIDS-associated large cell lymphomas (LCL). IL-6 receptor (IL-6R) and IL-10 expression was detected in a majority of the tumor specimens tested. IL-6 expression was detected in 5 of 16 lymphomas that also expressed IL-6R, suggestive of an autocrine mechanism of disease. A subset of tumor samples described as mixed immunophenotype contained large numbers of infiltrating T lymphocytes and macrophages. Immunoperoxidase staining of a representative tumor of mixed immunophenotype demonstrated the presence of HIV-infected macrophages that also stained with anti-IL-6. This finding suggests that IL-6 produced by nonlymphoid cells may act as a paracrine growth factor for tumor cells that express IL-6R. Although earlier studies of AIDS Burkitt's lymphoma cell lines suggested that IL-10 expression required EBV infection, 7 of 12 AIDS LCLs that expressed IL-10 did so in the absence of EBV by EBER in situ hybridization. Because AIDS LCLs frequently express cell surface CD5, we speculate that IL-10 may act as an autocrine or paracrine growth factor for this class of lymphoma. These studies suggest that IL-6 and IL-10 are involved in the pathogenesis of AIDS-associated large cell and mixed immunophenotype lymphoma.