Abstract
Early in ontogeny, the secondary lymphoid organs become populated with numerous cells of mesodermal origin which forms both the lymphoid and stromal elements. The critical receptor/ligand interactions necessary for lymphoid organogenesis to occur are for the most part unknown. Although lymphotoxin-alpha (LT alpha) has been shown to be required for normal lymph node, Peyer's patch, and splenic development, it is unclear if soluble LT alpha 3, and/or cell-bound lymphotoxin-alpha beta (LT alpha beta) mediate these developmental events. Here we report that blocking LT alpha beta/lymphotoxin-beta receptor (LT beta R) interaction in vivo by generating mice which express a soluble LT beta R-Fc fusion protein driven by the human cytomegalovirus promoter results in an array of anatomic abnormalities affecting both the spleen and Peyer's patches, but not the lymph nodes. These results demonstrate that surface LT alpha beta ligand plays a critical role in normal lymphoid organ development.