Tolerance in T cells accompanied by effector function in lymphoid organs.

2004 SEP 1 - (NewsRx.com & NewsRx.net) -- Oral tolerance in T cells is accompanied by induction of effector function in lymphoid organs after systemic immunization.

"The physiological ramifications of oral tolerance remain poorly understood. We report here that mice fed ovalbumin (OVA) exhibit oral tolerance to subsequent systemic immunization with OVA in adjuvant, and yet they clear systemic infection with a recombinant OVA-expressing strain of Salmonella enterica serovar Typhimurium better than unfed mice do. Mice fed a sonicated extract of S. enterica serovar Typhimurium are also protected against systemic bacterial challenge, and the protection is Th1 mediated, as feeding enhances clearance in interieukin-4-null (IL-4[superscript]-/-) and IL-10[superscript]-/- mice but not in gamma interferon-null (IFN-gamma[superscript]-/-) mice," scientists in India report.

"When T-cell priming in vivo is tracked temporally in T-cell receptor-transgenic mice fed a single low dose of OVA, CD4 T-cell activation and expansion are restricted largely to mucosal lymphoid organs," reported Neetha Parameswaran and colleagues at the National Institute of Immunology in New Delhi. "However, T cells from spleens and peripheral lymph nodes of fed mice proliferate and secrete IFN-gamma when restimulated with OVA in vitro, indicating the presence of primed T cells in systemic tissues following oral exposure to antigen. Nonetheless, oral tolerance can be observed in the fed mice as reduced recall ...