title: Inhibition of lymphocyte proliferation by bovine trophoblast protein-1 (type I trophoblast interferon) and bovine interferon-alpha I1.
abstract: Bovine trophoblast protein-1 (bTP-1) is a Type I interferon secreted by the bovine trophoblast from about Day 15 of pregnancy. It is not known whether bTP-1 has functional properties in common with other interferons. The aim of the present study was to determine whether bTP-1 inhibits proliferation of lymphocytes induced by mitogens, mixed lymphocyte cultures (MLC) and interleukin-2 (IL-2) and, if so, whether this activity is similar to that of a related interferon, bovine interferon-alpha I1 (bIFN-alpha I1). Stimulation of lymphocyte proliferation caused by phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) was inhibited by bTP-1 and bIFN-alpha I1 without any reduction in cell viability. Maximum or near-maximum inhibition (less than 50%) was achieved at concentrations of 0.5-5.0 nM of bTP-1 and bIFN-alpha I1. Cells stimulated with PWM were less inhibited than cells stimulated with PHA and Con A. Both bTP-1 and bIFN-alpha I1 inhibited MLC to a greater degree than lectin-stimulated cells (maximum inhibition was 78% or greater). Also, bTP-1 and bIFN-alpha I1 slightly inhibited incorporation of [3H]thymidine ([3H]TdR) induced by the combination of phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA), and calcium ionophore A23187. Finally, bTP-1 and bIFN-alpha I1 had bimodal effects on incorporation of [3H]TdR by IL-2-induced lymphocytes. Incorporation of [3H]TdR was increased at 0.005 nM and 0.05 nM concentrations while higher concentrations caused a slight decrease in [3H]TdR incorporation. Results confirm that bTP-1 inhibits lymphocyte proliferation in a manner similar to that caused by the leukocyte-derived interferon, bIFN-alpha I1. Incomplete inhibition of mitogen-induced proliferation and differences in degree of inhibition between various stimulators suggest that bTP-1 and bIFN-alpha I1 preferentially inhibit certain lymphocyte subpopulations. Local inhibition of lymphocyte proliferation caused by bTP-1 may help protect the allogeneic conceptus from immune responses to fetal antigens or regulate the release of cytokines from endometrial lymphocytes.
authors.affiliation: Dairy Science Department, University of Florida, Gainesville 32611-0701.
authors.forename: B
authors.initials: B
authors.lastname: Skopets
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: W W
authors.initials: WW
authors.lastname: Thatcher
authors.forename: R M
authors.initials: RM
authors.lastname: Roberts
authors.forename: P J
authors.initials: PJ
authors.lastname: Hansen
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000037:antagonists & inhibitors; D002417:Cattle; D005260:Female; D007370:Interferon Type I / Q000494:pharmacology*; D007376:Interleukin-2 / Q000037:antagonists & inhibitors; D008213:Lymphocyte Activation / Q000187:drug effects*; D007959:Lymphocyte Culture Test, Mixed; D008934:Mitogens / Q000037:antagonists & inhibitors; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000494:pharmacology / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007370:Interferon Type I; D007376:Interleukin-2; D008934:Mitogens; D011257:Pregnancy Proteins; D011994:Recombinant Proteins; C020947:interferon tau; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate