Kinetics of the mucosal antibody secreting cell response and evidence of specific lymphocyte migration to the lung after oral immunisation with attenuated S-enterica var. typhimurium

The kinetic of mucosal secretory responses elicited by the vaccine vector S almonella enterica var. typhimurium (S. typhimurium) was examined by enzyme linked immunospot (ELISPOT) and compared with serum responses. Mice immuni sed orally with BRD509, the aroA, aroD mutant of virulent S. typhimurium SL 1344 expressing the C Fragment of tetanus toxin (TT), simultaneously develo ped an IgA antibody secreting cells (ASC) response in the gastrointestinal lamina propria, the spleen and the lung, against both S. typhimurium lipopo lysaccharide (LPS) and TT. The magnitude of the ASC response was greatest i n the gut, was boosted by a secondary immunisation at day 25, and the kinet ic of the response did not correlate with the appearance of serum antibodie s. This study suggests that S. typhimurium can engage the common mucosal im mune system to effect mucosal secretory responses at distal sites, however, the magnitude of the responses is both greatest in the gut and antigen-spe cific. The ASC origin of the serum antibodies specific for S. typhimurium a nd antigens expressed by the bacterium is yet to be elucidated. (C) 2000 Fe deration of European Microbiological Societies. Published by Elsevier Scien ce B.V. All rights reserved.