DISTINCT ROLES IN LYMPHOID ORGANOGENESIS FOR LYMPHOTOXIN-ALPHA AND LYMPHOTOXIN-BETA REVEALED IN LYMPHOTOXIN BETA-DEFICIENT MICE

Lymphotoxin alpha (LT alpha)-deficient mice revealed critical roles fo r LT alpha in lymphoid organogenesis, but it is not clear whether LT a lpha functions through an LT alpha homotrimer (LT alpha(3)) or LT alph a/beta heterotrimers. We generated LT beta-deficient mice and found th em to lack Peyer's patches, peripheral lymph nodes, splenic germinal c enters, and follicular dendritic cells. Unlike LT alpha-deficient mice , LT beta-deficient mice had cervical and mesenteric lymph nodes. Furt hermore, the mesenteric lymph nodes had germinal center-like regions, although these structures appeared to lack follicular dendritic cells. The absence of cervical and mesenteric lymph nodes in LT alpha-defici ent mice, and yet their presence in LT beta-deficient mice and in mice deficient in tumor necrosis factor receptor types I and II, suggest t hat LT alpha(3) may signal via an as yet unidentified receptor.