title: Human recombinant interleukin-6 enhances antibody-dependent cellular cytotoxicity of human tumor cells mediated by human peripheral blood mononuclear cells.
abstract: The effects of human recombinant interleukin-6 (hrIL-6) on antibody-dependent cellular cytotoxicity (ADCC) activity mediated by human peripheral blood mononuclear cells (PMNC) were investigated. Human PMNC were preincubated for 24 h with various concentrations of hrIL-6 and were used as effector cells in a 4-h 51Cr-release assay. The ability of hrIL-6 to augment ADCC was measured using anti-colorectal carcinoma mAbs D612, 17.1A and 31.1 (each directed against a distinct tumor antigen) and using three human colorectal carcinoma cell lines, LS-174T, WiDr and HT-29, as targets. A significant increase in ADCC activity was observed after PMNC were preincubated in 100-400 U/ml but not in lower concentrations of hrIL-6. Variations in activities of PMNC among donors were observed. Non-specific mAb showed no effect in augmenting ADCC activity. hrIL-6 treatment did not augment non-specific (non-mAb-mediated) cytotoxicity. The enhancement of ADCC activity was blocked by the addition of an antibody against hrIL-6 but not by an antibody to the IL-2 receptor (capable of blocking the induction of lymphokine-activated killer cell cytotoxicity by IL-2), suggesting that hrIL-6 augmentation of ADCC activity may not be mediated through IL-2. These results demonstrate that hrIL-6 augments ADCC activity of human PMNC using mAbs to human tumor antigens and human tumor cells as targets, suggesting a potential role for IL-6 in combination with anti-cancer antibodies for cancer immunotherapy.
authors.affiliation: Laboratory of Tumor Immunology and Biology, National Cancer Institute, NIH, Bethesda, MD 20892.
authors.forename: K Y
authors.initials: KY
authors.lastname: Tsang
authors.forename: M D
authors.initials: MD
authors.lastname: Finch
authors.forename: F J
authors.initials: FJ
authors.lastname: Primus
authors.forename: J
authors.initials: J
authors.lastname: Schlom
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects*; D000943:Antigens, Differentiation / Q000032:analysis; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000276:immunology / Q000494:pharmacology*; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D011961:Receptors, Fc / Q000032:analysis; D017452:Receptors, IgG; D015375:Receptors, Interleukin-2 / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D007376:Interleukin-2; D015850:Interleukin-6; D011961:Receptors, Fc; D017452:Receptors, IgG; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins