Abstract
BACKGROUND: We have previously demonstrated that an alkaline extract of shredded pinecones yields a polyphenylpropanoid polysaccharide complex (PPC) that functions as an orally active immune adjuvant. Specifically, oral PPC can boost the number of antigen-specific memory CD8+ T cells generated in response to a variety of vaccine types (DNA, protein, and dendritic cell) and bias the response towards one that is predominately a T helper 1 type. METHODS: An immune response was initiated by intraperitoneal injection of mice with Staphylococcus enterotoxin B (SEB). A group of mice received PPC by gavage three times per day on Days 0 and 1. The draining lymph nodes were analyzed 48-96 h post-injection for the numbers of reactive T cells, cytokine production, the generation of reactive oxygen species, and apoptotsis. RESULTS: In this study we examined whether the ability of PPC to boost a T cell response is due to an effect on the proliferative or contraction phases, or both, of the primary response. We present data to demonstrate that oral PPC significantly enhances the primary T cell response by affecting the expansion of T cells (both CD4 and CD8) during the proliferative phase, while having no apparent effects on the activation-induced cell death associated with the contraction phase. CONCLUSIONS: These findings suggest that PPC could potentially be utilized to enhance the T cell response generated by a variety of prophylactic and therapeutic vaccines designed to target a cellular response.