F. Arechavaleta et al., A TAENIA-SOLIUM METACESTODE FACTOR NONSPECIFICALLY INHIBITS CYTOKINE PRODUCTION, Parasitology research, 84(2), 1998, pp. 117-122
Studies of the immune response in chronic helminth infections suggest
that parasites modulate the host's immune response. Taenia solium meta
cestodes, in particular, produce molecules that down-regulate cell-med
iated immunity. We have described a small RNA peptide termed metacesto
de factor (MF) that depresses the murine immune response to Salmonella
typhimurium antigens. MF inhibits mitogen-induced proliferation, humo
ral and cellular responses to metacestode antigens, and inflammation s
urrounding metacestodes implanted subcutaneously in mice. To assess th
e effects of MF on cytokine production we stimulated murine spleen cel
ls in vitro with concanavalin A and measured cytokine concentrations i
n the culture supernatants by enzyme-linked immunosorbent assay. When
cultured with MF, the cells showed significantly decreased production
of interleukin 2 (IL-2), interferon-gamma (IFN-gamma), and IL-4 as com
pared with mitogen alone. Exogenous rIL-2 and rIL-4 largely restored t
he proliferative response (85% and 71% of control cells, respectively)
. MF also decreased production of tumor necrosis factor-alpha (TNF-alp
ha) by macrophages stimulated with lipopolysaccharide and IFN-gamma. T
he TNF-alpha concentration was inversely correlated with the MF concen
tration. Experiments using spleen cells from mice treated with MF also
showed a significant reduction in IL-4 concentration. These results s
uggest that MF inhibits cytokine production without regard to cell typ
e or cytokine. This may explain the function of this molecule as an in
hibitor of the host inflammatory and immune responses.