The regulatory role of transforming growth factor-beta in activation of milk mononuclear cells.
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.
Ayoub
I A
IA
Department of Pathobiology, University of Connecticut, Storrs 06269-3089, USA.
Yang
T J
TJ
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*
D007166:Immunosuppressive Agents; D007376:Interleukin-2; D016212:Transforming Growth Factor beta