Bacterial surface components and extracellular compounds, particularly flagella, lipopolysaccharides (LPSs), and exopolysaccharides (EPSs), in combination with environmental signals and quorum-sensing signals, play crucial roles in bacterial autoaggregation, biofilm development, survival, and host colonization. The nitrogen-fixing species Sinorhizobium meliloti (S. meliloti) produces two symbio...

Several classes of anergic T cells are capable of suppressing naive T cell proliferation and thereby limiting immune responses. Activated T cells, although not anergic, are transiently refractory to restimulation with Ag. We examine in this study whether activated refractory murine T cells can also suppress naive T cell responses. We find that they can, and that they exhibit many of the suppres...