The spleen and organized lymph nodes are not essential for the development of gut-induced mucosal immune responses in lymphotoxin-alpha deficient mice.
Lymphotoxin knock-out (KO) mice generate specific immune responses to orally administered immunogens despite having neither gut-associated nor peripheral lymphoid tissues. The spleen, therefore, was expected to play a role in the generation of immune responses in these KO mice. KO and wild-type (wt) mice were splenectomized and orally immunized with Salmonella typhimurium. Splenectomy produced the most profound effects on serum and fecal IgA levels in KO mice. Total and antigen-specific serum and fecal IgA were increased in splenectomized wt mice but decreased in splenectomized KO mice. Antigen-specific serum IgG was decreased in both KO and wt splenectomized mice while total IgG increased in splenectomized wt mice. Both splenectomized wt and KO mice demonstrated a compensatory expansion of the lamina propria compartment characterized by a significant increase in the number of IgA spot-forming cells. KO mice demonstrated further compensation for the loss of the spleen in the accelerated development of ectopic lymphoid tissues. We conclude that the spleen plays a prominent role as a lymphoid organ in KO mice but its removal does not abolish immune responsiveness. Residual immune responsiveness in splenectomized KO mice following oral immunization appears to be due to expansion and/or development of alternate effector compartments.
Davis
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Department of Microbiology, University of Tennessee, Knoxville, Tennessee, 37996, USA.
Knight
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Rouse
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D000818:Animals; D002828:Choristoma; D005260:Female; D005753:Gastric Mucosa / Q000276:immunology*; D007109:Immunity; D008198:Lymph Nodes / Q000502:physiology*; D008221:Lymphoid Tissue; D008233:Lymphotoxin-alpha / Q000235:genetics* / Q000276:immunology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D013154:Spleen / Q000502:physiology*; D013156:Splenectomy; D013158:Splenic Diseases / Q000276:immunology
D008233:Lymphotoxin-alpha