title: The regulatory role of transforming growth factor-beta in activation of milk mononuclear cells.
abstract: OBJECTIVE
  Immunoregulatory role of milk mononuclear cells and cytokines during the involution of the mammary gland.
  
  
  METHODS
  Bioassays were used to determine the levels of transforming growth factor beta (TGF-beta) and interleukin-2 (IL-2) and their effects on milk mononuclear cells (MMCs).
  
  
  RESULTS
  MMCs collected from involuting glands were less responsive to Con A stimulation than peripheral blood mononuclear cells (PBMCs), and purified huTGF-beta 1 inhibited the activation of both MMCs and PBMCs by Con A. Furthermore, secretions collected over a period of approximately 4 weeks into the involution period contained high levels of active TGF-beta and extremely high levels of latent TGF-beta, MMCs stimulated with Con A produced higher levels of IL-2 than did the PBMCs of the same animals, and bovine milk TGF-beta and huTGF-beta 1 significantly inhibited the IL-2 production by MMCs. Mammary secretions of involuting glands did not contain any detectable levels of IL-2, and they inhibited the growth of the IL-2-dependent bovine lymphoblastoid T cell line (BLTC), even in the presence of 10 U/ml of rBo IL-2.
  
  
  CONCLUSIONS
  The findings suggest that TGF-beta is a major immunoregulatory factor in the involuting mammary gland.
authors.affiliation: Department of Pathobiology, University of Connecticut, Storrs 06269-3089, USA.
authors.forename: I A
authors.initials: IA
authors.lastname: Ayoub
authors.forename: T J
authors.initials: TJ
authors.lastname: Yang
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D007166:Immunosuppressive Agents / Q000276:immunology*; D007376:Interleukin-2 / Q000096:biosynthesis; D007774:Lactation / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008213:Lymphocyte Activation; D008321:Mammary Glands, Animal / Q000276:immunology; D008892:Milk / Q000166:cytology / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000276:immunology*
chemical_list: D007166:Immunosuppressive Agents; D007376:Interleukin-2; D016212:Transforming Growth Factor beta