title: Monocyte-independent interleukin-2 production and proliferation of human T cells in response to murine hybridomas expressing the OKT3 monoclonal antibody: interleukin-1 is not required for T-cell proliferation.
abstract: We report a new, monocyte-independent system for the induction of activation and proliferation of human T cells in response to murine hybridomas expressing the OKT3 monoclonal antibody (OKT3 hybridomas). Incubation of nylon-wool-nonadherent (NA) lymphocytes or purified T cells with OKT3 hybridomas resulted in interleukin-2 (IL-2) production, expression of IL-2 receptor, modulation of the CD3 antigen, and proliferation. In contrast, murine hybridomas (OKT4, OKT8, anti-HLA-DR, and others) expressing monoclonal antibodies (mAb) other than OKT3 did not induce T-cell activation and proliferation. T cells did not respond to OKT3 mAb alone. OKT3 hybridomas alone did not produce interleukin-1 (IL-1) or other soluble factors that might be involved in the induction of IL-2 production by T cells, and they did not contain membrane-bound IL-1. In addition, IL-1 activity was not detected in cultures of NA-lymphocytes and OKT3 hybridomas, clearly demonstrating that IL-1 was not required, at least in this system, for T-cell activation and proliferation. Direct cell-cell contact between T cells and OKT3 hybridomas was required for IL-2 production. Thirty to fifty percent of T cells formed conjugates with the OKT3 hybridomas but not with the OKT4 or OKT8 hybridomas. Both conjugate formation and IL-2 production were significantly inhibited by the OKT3 mAb and by the anti-LFA-1 mAb. The cells responsible for IL-2 production were found to be of the T3+ T4+ T8- Leu 7- Leu 11- phenotype. IL-2 activity produced by NA-lymphocytes in response to OKT3 hybridomas became detectable as early as 1 hr and reached a maximum by 8 hr, preceding IL-2 receptor expression, modulation of the CD3 antigen, and [3H]thymidine incorporation of T cells. T cells produced higher concentrations of IL-2 in response to OKT3 hybridomas than in response to equal numbers of monocytes and OKT3 mAb. Addition of monocytes to cultures of T cells and OKT3 hybridomas resulted in suppression of IL-2 production in a concentration-dependent manner, suggesting that monocytes regulate the levels of IL-2 production. This monocyte-independent system may be useful for further dissection of T-cell activation and proliferation and its regulation by monocytes.
authors.affiliation: Department of General Surgery, University of Texas System Cancer Center, Houston 77030.
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: C M
authors.initials: CM
authors.lastname: Balch
authors.forename: C D
authors.initials: CD
authors.lastname: Platsoucas
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000502:physiology*; D000943:Antigens, Differentiation / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D002450:Cell Communication; D002478:Cells, Cultured; D006801:Humans; D006825:Hybridomas / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D007166:Immunosuppressive Agents / Q000502:physiology; D007375:Interleukin-1 / Q000502:physiology; D007376:Interleukin-2 / Q000096:biosynthesis*; D007700:Kinetics; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1; D009000:Monocytes / Q000276:immunology*; D010641:Phenotype; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D007166:Immunosuppressive Agents; D007375:Interleukin-1; D007376:Interleukin-2; D016169:Lymphocyte Function-Associated Antigen-1; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2