Proper lymph node (LN) development requires tumor necrosis factor-related a
ctivation-induced cytokine (TRANCE) expression Here we demonstrate that the
defective LN development in TRANCE(-/-) mice con-elates with a significant
reduction in lymphotoxin (LT)alpha beta (+)alpha (4)beta (+)(7)CD45(+)CD4(
+)CD3(-) cells and their failure to form clusters in rudimentary mesenteric
LNs. Transgenic TRANCE overexpression in TRANCE(-/-) mice results in selec
tive restoration of this cell population into clusters, and results in full
LN development. Transgenic TRANCE-mediated restoration of LN development r
equires LT alpha beta expression on CD45(+) CD4+CD3- cells, as LNs could no
t be induced in LT alpha (-/-) mice. LTa-/- mice also showed defects in the
fate of CD45(+)CD4(+)CD3(-) cells similar to TRANCE(-/-) mice. Thus, we pr
opose that both TRANCE and LT alpha beta regulate the colonization and clus
ter formation by CD45(+) CD4(+)CD3(-) cells in developing LNs, the degree o
f which appears to correlate with the state of LN organogenesis.