title: Interleukin-12 overcomes paclitaxel-mediated suppression of T-cell proliferation.
abstract: The antineoplastic agent paclitaxel (TAXOL) is a potent inhibitor of tumor cell division and a useful chemotherapeutic for the treatment of refractory ovarian and breast carcinoma. Multiple immune system actions have been ascribed to paclitaxel, including the capacity to induce macrophage antitumor cytotoxic molecule production. However, T-cells are susceptible to paclitaxel's cytostatic functions, and no studies have investigated the effects of direct paclitaxel administration on lymphocyte function in the tumor-bearing host (TBH). Because paclitaxel is currently used as an antitumor chemotherapeutic agent and tumor growth alters leukocyte functions, we assessed T-cell function following chemotherapeutic-type paclitaxel treatment. Paclitaxel administration significantly compromised the proliferative capacity of both normal host and TBH lymphocytes in vitro. Although tumor growth impaired T-cell interferon-gamma (IFN-gamma) production, paclitaxel treatment did not alter IFN-gamma. We speculate that the immunostimulatory cytokine interleukin-12 (IL-12), which promoted T-cell activation and proliferation, was capable of reversing paclitaxel-mediated immunosuppression. Exogenous IL-12 fully reconstituted proliferative reactivity and enhanced IFN-gamma production by both normal host and TBH lymphocytes in vitro. Collectively, these data suggest that chemotherapeutic paclitaxel regimens impart significant but reversible inhibition of lymphocyte populations, and IL-12 may be a useful ancillary immunotherapeutic to overcome paclitaxel-induced modulation of lymphocyte activities.
authors.affiliation: Department of Biology, Virginia Polytechnic Institute, State University, Blacksburg 24061-0406, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Mullins
authors.forename: M D
authors.initials: MD
authors.lastname: Koci
authors.forename: C J
authors.initials: CJ
authors.lastname: Burger
authors.forename: K D
authors.initials: KD
authors.lastname: Elgert
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004347:Drug Interactions; D007166:Immunosuppressive Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D017239:Paclitaxel / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000972:Antineoplastic Agents, Phytogenic; D007166:Immunosuppressive Agents; D018664:Interleukin-12; D007371:Interferon-gamma; D017239:Paclitaxel