Effect of endotoxin on cytokine production and cell dynamics in mice.

Previous studies have shown that endotoxin potentiates immune responses by direct stimulation of B cells and macrophages. In the present study, we assessed the ability of endotoxin to stimulate cells from different lymphoid tissue compartments to release cytokines. The in vitro stimulation of macrophages with endotoxin resulted in the production of IL-1 and TNF-alpha in a dose and time-dependent manner. Endotoxin also induced the production of IL-2, IFN-gamma and IL-4 secretion in a dose dependent manner in cultured spleen, mesenteric lymph nodes and Peyer's patches cells. The intraperitoneal administration of endotoxin in mice resulted in the accumulation of leucocytes in the peritoneal cavity and in the increase of IL-1, IL-6, TNF-alpha and IFN-gamma concentration in serum. In conclusion, this study confirmed that endotoxin possesses immunomodulatory activities capable of stimulating immune functions both in vitro and in vivo.