Figure 1

Specificity and sensitivity of IA^s/PLP 139-151 dextramers. PLP 139-151 and control dextramers were prepared at the indicated molar ratios by mixing SA-conjugated dextran-PE molecules with biotinylated soluble IA^s molecules containing the peptide sequence for PLP 139-151. The amount of IA^s protein used in each of the indicated molar ratios was as follows: 60:1, 40:1, 20:1, 1:1 and 1:20, 0.43 μg; 1:40, 0.86 μg and 1:60, 1.29 μg. To prepare tetramers, 0.9 μg of IA^s protein containing PLP 139-151 or TMEV 70-86 was used. PLP-reactive cells were generated from SJL mice immunized with PLP 139-151, and viable cells harvested on day 6 poststimulation were stained with dextramers or tetramers followed by anti-CD4 and 7-AAD. After acquiring the cells by FC, percentages of dext⁺ or tet⁺ cells were enumerated in the live (7-AAD^-) CD4 subset (top panel). In each FC plots, the upper left quadrants indicate CD4⁺ cells containing CD4^high (upper) and CD4^low (lower) subsets. The mean ± SEM values representing three individual experiments are shown (bottom panel). Control, TMEV 70-86.