Lag-3^−/− Tcon accelerates GVHD.

<p>Lethally irradiated Balb/c recipients were transplanted with 5×10⁶ TCD-BM and various doses of Tcon from either Lag-3^−/− or WT C57Bl/6 mice and monitored for survival (A–C) and GVHD score (D–E). (A) Mice were infused with TCD-BM and 1×10⁶ Tcon (n = 15/group, P = 0.009), (B) TCD-BM and 7.5×10⁵ Tcon (n = 10/group, P<0.001), and (C) TCD-BM and 5×10⁵ Tcon (n = 10/group, P<0.001). P value is calculated for survival rate differences between mice receiving Lag-3^−/− Tcon and WT Tcon. Data in graphs are pooled from two independent experiments. (D) and (E) represent the GVHD score of mice 5 days (D) and 25 days (E) after transplantation. Mice receiving TCD-BM and Lag-3^−/− Tcon had a significantly higher GVHD score than mice receiving TCD-BM and WT Tcon (P<0.005). (F) Histopathologic analysis of GVHD target organs isolated at day 8 after transplant. High magnification photomicrographs of colon (upper panels) and small intestine (lower panels) reveal a more severe GVHD in mice transplanted with Lag-3^−/− Tcon as evidenced by increased inflammatory cell infiltrate in the lamina propria (black asterisk) and intestinal gland lumina (white arrowhead), loss of microarchitecture of intestinal glands that are lined by poorly-differentiated epithelial cells and a larger number of apoptotic bodies within the epithelial layer (black arrowhead). H&E stain, scale bar = 50 microns. (G) Mice received 5×10⁶ TCD-BM and 1×10⁶ different combinations of CD4 and CD8 T cells. One group of mice received Lag-3^−/− CD4+ WT-CD8 T cells (n = 10), one received WT-CD4+ Lag-3^−/− CD8 T cells (n = 10, P<0.0001), one group received Lag-3^−/−CD4+Lag-3^−/−CD8T cells (Lag-3^−/− Tcon, n = 15) and the last group received WT-CD4+WT-CD8 T cells (WT Tcon, n = 15). P values are calculated for survival rate differences between mice receiving Lag-3^−/− Tcon and WT-CD4+Lag-3^−/−CD8 T cells. Data are pooled from two independent experiments.