Dendritic cells (DC) are potent inducers of acquired immunity due to their ability to present antigens in the context of a costimulatory environment and consequently serve an essential role in vaccine efficacy. Strategies to enhance their function, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 treatment to induce DC differentiation from peripheral blood monocytes, may therefore be useful as vaccine adjuvants. We now have evaluated the effect of recombinant GM-CSF on the differentiation of DC in swine. GM-CSF mRNA was readily detected in porcine splenocytes, with increased levels following treatment of the cells with ConA and LPS. Porcine GM-CSF was cloned and expressed in the methylotrophic yeast, Pichia pastoris, as a glycosylated protein that induced proliferation of porcine bone marrow cells. P. pastoris-derived GM-CSF induced expression of antigen presenting (MHC class II) and costimulatory (CD80-CD86) molecules and enhanced antigen presenting cell (APC) function consistent with the induction of functional DC. Thus, recombinant GM-CSF produced by P. pastoris may be a potent adjuvant for swine vaccines.
Bibliographical noteFunding Information:
The authors gratefully appreciate the assistance of Kevin Murphy, Pierce Endogen, Inc., for assistance with protein expression and purification. This research was supported in part by United States Department of Agriculture grants 97-33610-4031 and 98-33610-6289 and National Institutes of Health grant K08AI01396.