Figure 7.

Splenic DCs which receive transferred proteins in vivo (CD11c⁺, CFSE^med) directly activate HEL-specific T cells. Purified HEL-specific transgenic B cells on the C57Bl/6 (H-2^bb) background were labeled with CFSE, loaded with HEL ex vivo and adoptively transferred into unmanipulated B10.BR (H-2^kk) recipients. Populations of DCs were tested for the ability to directly activate T cells in vitro. The CD11c⁺ CFSE⁻, CD11c⁺ CFSE^med, and CD11c⁻ CFSE^med populations identified in the Figure were sorted by flow cytometry and cultured overnight in vitro with HEL-specific T cells. The purity of the sorted CD11c⁺, CFSE^med population was 89%. Data were gated for live lymphocytes. In the presence of exogenous HEL, 70.8% of HEL-specific T cells expressed CD69, in the absence of antigen, 5.6% of HEL-specific T cells expressed CD69. All points are data for three culture wells, except for one point, without error bars in the total APC which represents the mean of two wells. Error bars represent the SD. The functional data are representative of six independent experiments.