Ia. Ayoub et Tj. Yang, THE REGULATORY ROLE OF TRANSFORMING GROWTH-FACTOR-BETA IN ACTIVATION OF MILK MONONUCLEAR-CELLS, American journal of reproductive immunology [1989], 38(2), 1997, pp. 121-128
PROBLEM: Immunoregulatory role of milk mononuclear cells and cytokines
during the involution of the mammary gland. METHOD OF STUDY: Bioassay
s were used to determine the levels of transforming growth factor beta
(TGF-beta) and interleukin-2 (IL-2) and their effects on milk mononuc
lear cells (MMCs). RESULTS: MMCs collected from involuting glands were
less responsive to Con A stimulation than peripheral blood mononuclea
r 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 TG
F-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 s
ecretions of involuting glands did not contain any detectable levels o
f IL-2, and they inhibited the growth of the IL-2-dependent bovine lym
phoblastoid 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 immu
noregulatory factor in the involuting mammary gland.