Role of TNF produced by lymphocytes in supporting organization of LNs. (A) B and T cells cooperate by TNF production in generation of FDCs in LNs. Mice were immunized i.p. with 108 SRBCs and analyzed on day 8. Frozen sections of MLNs were stained with indicated antibodies. Magnification is ×200. Note the reduction of FDCs and GCs in both B-TNF KO mice (shown by arrows) and the complete absence of FDCs and GCs in T,B-TNF and TNF KO mice. Representative images from 1 of 3 independent experiments (n = 5 mice per group) are shown. Right panel shows quantification of CR1- and PNA-positive areas. Data represent means ± SEM; *P < .05, **P < .01. (B) TNF from B and T cells acts in concert in regulating TNF-dependent genes in LNs. Analysis of TNF and TNF-dependent gene expression in MLNs of indicated mutant mice (represents 1 of 2 independent experiments, n = 3 mice per group, means ± SD); *P < .05, **P < .01.
