The vessels of the islets were weakly positive for intercellular adhesion molecule 1 (ICAM-1), strongly positive for platelet endothelial cell adhesion molecule 1 (PECAM-1), and negative for vascular cell adhesion molecule-1 and P-selectin (13). of CD4 T cells into normal noninflamed islets. Thus, the anatomy of the islet of Langerhans permits the specific localization of diabetogenic T cells at a time when there is no inflammation in the islets. and Table 1). T cells were not found in the stroma at the time of their first identification in islets (Table S1). The same number of 3A9 TCR transgenic T cells transferred into IP-HEL did not localize to the islets of IP-HEL mice. To exclude effects of sublethal irradiation, activated 3A9 T cells were transferred into nonirradiated IP-HEL mice and found to be equally distributed as seen in sublethally irradiated recipients. Activated 3A9 T cells were not detected in the islets of sublethally irradiated B10.BR mice; that is, nonspecific localization was not observed at any time point (Fig. 1and Table 1). Unstimulated BDC T cells were not detected until 72 h and only in 20% of islets (Fig. 1and and and Table S2). The administration of the specific mAb (antiCI-Ak) partially reduced the localization to 33% of the islets (Fig. 2 and and Table S2), however. By 48 h, the islets were infiltrated equally and the difference in the number of T cells per islet was not statistically significant (Fig. 2and Table S2). Increasing the number of injections of anti-class II MHC mAb (1 d before T-cell transfer and 1 day after) gave the same results. Open in a separate window Fig. 2. Localization of CD4 T cells to islets during partial inhibition by anti-class II MHC mAb. ( 0.05 [not significant (ns)]; * 0.05; ** 0.01; *** 0.001; **** 0.0001. The localization of BDC T cells after 48 h was affected by the administration of the mAb to I-Ag7 but not by that of antiCI-Ak. In four experiments, the percentage of islets bearing CD4+ T cells decreased from 69% in untreated mice and 70% in mice treated with the irrelevant antiCI-Ak mAb to 27% in mice treated with antiCI-Ag7 mAb (Fig. 2 and and Table S3). By 72 h, all groups showed the same extent of T-cell infiltration (91C99%) (Fig. 2and Table S3). The partial inhibition of CD4 T-cell entry into the islet by class II MHC mAb suggested other contributing factors, such as a role for adhesion molecules. The vessels of the islets were weakly positive for intercellular adhesion molecule 1 (ICAM-1), strongly EBI-1051 positive for platelet endothelial cell adhesion molecule EBI-1051 1 (PECAM-1), and negative for vascular cell adhesion molecule-1 and P-selectin (13). Administering a blocking mAb to PECAM-1 did not affect T-cell localization into islets; however, a blocking CD3G mAb to ICAM-1 partially reduced the localization of activated 3A9 T cells transferred into IP-HEL mice to 41% at 24 h from control rat IgG of 71% (Fig. 3 and and 0.05 [not significant (ns)]; * 0.05; *** 0.001; **** EBI-1051 0.0001. Activated BDC T cells were transferred into sublethally irradiated NOD.ICAM-1+/+ or NOD.ICAM-1?/? mice (27) that received either antiCI-Ak or antiCI-Ag7 mAb (Fig. 3 and and promoter. Blood vessels were stained for PECAM-1). The area of physical contact was evident as fluorescence colocalization (Fig. 5and axis (top view) from a stack of 30 optical sections (0.5-m increments). (and reconstructions (side view) of same image stack (indicated as white lines). The image shows a DC dendrite inside the vessel (yellow merged color indicated by arrows). (= 108). Data were obtained from 17 different visualized fields from two experiments. (axes show the number of anti-class II beads per islet in B10.BR and NOD mice, respectively, representing compiled data from three independent experiments. ** 0.01; **** 0.0001. (test was used to determine the level of significant differences between samples and was plotted using GraphPad Prism 5 (GraphPad Software, Inc.). The following values were detected: **** 0.0001, *** 0.001, ** 0.01, * 0.05, and 0.05 (not significant). Median numbers of T cells per infiltrated islets in all experiments were obtained by including only islets containing infiltrating T cells. Supplementary Material Supporting Information: Click here to view. Acknowledgments.
