sLP-mediated radioprotection and cytokine induction is TLR2-dependent and involves both bone marrow and non-bone marrow cells.

<p>(A) TLR2-dependence of sLP-mediated radioprotection. Groups of isogenic TLR2(−/−) and wild type C57BL/6 mice (<i>n = 15</i>/group) were injected sc with vehicle (PBS) or sLP (3 µg/mouse) and irradiated (9 Gy TBI) 24 h later. Survival was monitored for 30 days. (B) sLP-mediated radioprotection in chimeric mice with wild type (WT) or TLR2(−/−) (TLR2KO) bone marrow (BM). Reciprocal radiation BM chimeras were generated as described in Results and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033044#s4" target="_blank">Materials and Methods</a>. Four types of chimeric mice, (i) TLR2KO BM transplanted into TLR2KO background, (ii) TLR2KO BM into WT background, (iii) WT BM into TLR2KO background, and (iv) WT BM into WT background, were injected sc with 20 µg/mouse sLP and irradiated with 9 Gy TBI 24 h later (<i>n = 8</i>/group). Survival was monitored for 30 days. (C) sLP-mediated cytokine induction in chimeric mice with WT or TLR2KO BM. The four types of chimeric mice described in (B) were injected with 20 µg/kg sLP without irradiation. Four sLP-injected mice of each genotype (2 males and 2 females) were euthanized at each time point (1, 2, 4, and 8 h post-injection) and serum cytokine levels of individual mice were determined using multiplex Luminex assays. The AUC for each cytokine was calculated as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033044#s4" target="_blank">Materials and Methods</a> and is presented for “TLR2KO to TLR2KO”, “TLR2KO-to-WT”, and “WT-to TLR2KO” chimeric mice as the percentage of that in “WT-to-WT” chimeric mice.