Modulation of immune function by a modified bovine whey protein concentrate.

The commercial preparation of dairy foodstuffs generates large volumes of by-products, many of which have as yet undocumented effects on mammalian immune function. In the present report, a modified whey protein concentrate (mWPC), derived as a by-product from the commercial manufacture of cheese, was tested for its ability to modulate murine immune function in vitro. The mWPC suppressed T and B lymphocyte proliferative responses to mitogens in a dose-dependent fashion. The mWPC also suppressed alloantigen-induced lymphocyte proliferation during a mixed leucocyte reaction, but showed no suppressive effect against IL-2-sustained proliferation of mitogen-activated T cell blasts. Other indices of lymphocyte activation, such as cytokine secretion and the formation of activated (CD25+) T cell blasts, were suppressed by the mWPC, suggesting that the mode of suppression may be to inhibit the lymphocyte activation process. Enzymatic digestion by pepsin and pancreatin, under physiologically realistic conditions in vitro, ablated the immunomodulatory function of the mWPC. These results are discussed in relation to the potential development of complex-mixture dairy products into health-modulating products.