Omental milky spots develop in the absence of lymphoid tissue-inducer cells and support B and T cell responses to peritoneal antigens.
The omentum is a site of B1 cell lymphopoiesis and immune responsiveness to T cell-independent antigens. However, it is unknown whether it supports immune responses independently of conventional lymphoid organs. We showed that the omentum collected antigens and cells from the peritoneal cavity and supported T cell-dependent B cell responses, including isotype switching, somatic hypermutation, and limited affinity maturation, despite the lack of identifiable follicular dendritic cells. The omentum also supported CD4+ and CD8+ T cell responses to peritoneal antigens and recruited effector T cells primed in other locations. Unlike conventional lymphoid organs, milky spots in the omentum developed in the absence of lymphoid tissue-inducer cells, but required the chemokine CXCL13. Although the lymphoid architecture of milky spots was disrupted in lymphotoxin-deficient mice, normal architecture was restored by reconstitution with lymphotoxin-sufficient hematopoietic cells. These results indicate that the milky spots of the omentum function as unique secondary lymphoid organs that promote immunity to peritoneal antigens.
Division of Allergy, Immunology and Rheumatology, University of Rochester, Rochester, NY 14642, USA.
Javier
J
Rangel-Moreno
Juan E
JE
Moyron-Quiroz
Damian M
DM
Carragher
Kim
K
Kusser
Louise
L
Hartson
Amy
A
Moquin
Troy D
TD
Randall
D000818:Animals; D000941:Antigens / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D054382:Chemokine CXCL13 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008208:Lymphatic System / Q000276:immunology* / Q000378:metabolism; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009852:Omentum / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D010537:Peritoneum / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D000941:Antigens; D054382:Chemokine CXCL13