EXPRESSION AND BIOLOGICAL-ACTIVITIES OF BOVINE INTERLEUKIN-4 - EFFECTS OF RECOMBINANT BOVINE INTERLEUKIN-4 ON T-CELL PROLIFERATION AND B-CELL DIFFERENTIATION AND PROLIFERATION IN-VITRO

Interleukin 4 (IL-4) is a pleotropic cytokine affecting a wide range of cell types in both the mouse and the human. These activities include regulation of the growth and differentiation of both T and B lymphocytes. The activities of IL-4 in nonprimate, nonmurine systems are not well established. Herein, we demonstrate in the bovine system that IL-4 upregulates production of IgM, IgG1, and IgE in the presence of a variety of costimulators including anti-IgM, Staphylococcus aureus cowan strain I, and pokeweed mitogen. IgE responses are potentiated by the addition of IL-2 to IL-4. Culture of bovine B lymphocytes with IL-4 in the absence of additional costimulators resulted in the increased surface expression of CD23 (low-affinity Fc(epsilon)RII), IgM, IL-SR, and MHC class II in a dose-dependent manner. IL-4 alone increased basal levels of proliferation of bulk peripheral blood mononuclear cells but in the presence of Con A inhibited proliferation. In contrast to the activities of IL-4 in the murine system, proliferation of T(H)1- and T(H)2-like clones was inhibited in a dose-dependent manner as assessed by antigen- or IL-2-driven in vitro proliferative responses. These observations are consistent with the role of IL-4 as a key player in regulation of both T and B cell responses. (C) 1995 Academic Press, Inc.