title: Interleukin-10 is expressed by bovine type 1 helper, type 2 helper, and unrestricted parasite-specific T-cell clones and inhibits proliferation of all three subsets in an accessory-cell-dependent manner.
abstract: Murine interleukin-10 (IL-10) is produced by type 2 helper (Th2) cells and selectively inhibits cytokine synthesis by type 1 helper (Th1) cells, whereas human IL-10 is produced by and inhibits proliferation and cytokine synthesis by both Th1 and Th2 subsets. This study reports that bovine IL-10 mRNA is expressed by Th0, Th1, and Th2 clones of bovine T cells specific for either Babesia bovis or Fasciola hepatica but not by two CD8+ T-cell clones. The antigen-induced proliferative responses of all three subsets of CD4+ cells were inhibited by human IL-10, and low levels (10 U/ml) of exogenous human IL-2 restored the suppressed response. However, proliferation of one Th1 clone was never inhibited but was enhanced by IL-10. Human IL-10 also inhibited the expression of gamma interferon and IL-4 mRNA in Th0 clones. In the absence of accessory cells (AC), the responses of Th clones to concanavalin A or IL-2 were not inhibited by IL-10, whereas antigen-specific responses of Th1 and Th2 cells were reduced when IL-10-pretreated macrophages were used as AC. Together, our results with bovine T cells support the concept that IL-10 primarily affects AC function and does not directly inhibit CD4+ T cells and demonstrate that the immunoregulatory effects of IL-10 are not selectively directed at Th1 populations, as they are in mice.
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station 77843.
authors.forename: W C
authors.initials: WC
authors.lastname: Brown
authors.forename: V M
authors.initials: VM
authors.lastname: Woods
authors.forename: C G
authors.initials: CG
authors.lastname: Chitko-McKown
authors.forename: S M
authors.initials: SM
authors.lastname: Hash
authors.forename: A C
authors.initials: AC
authors.lastname: Rice-Ficht
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000187:drug effects / Q000276:immunology; D000947:Antigens, Helminth / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology*; D016793:Babesia bovis / Q000276:immunology; D001483:Base Sequence; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002417:Cattle; D003208:Concanavalin A / Q000494:pharmacology; D017931:DNA Primers / Q000737:chemistry; D005210:Fasciola hepatica / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D008969:Molecular Sequence Data; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D000947:Antigens, Helminth; D000953:Antigens, Protozoan; D017931:DNA Primers; D007376:Interleukin-2; D003208:Concanavalin A