Engagement with the MHC:peptide complex down-regulates the TCR.
TCR37.33 were incubated for 24 h with equal numbers of APC
prepulsed with or without increasing concentration of peptides.
(A) At each peptide concentration, the supernatants were
collected after 24 h and the released IL-2 assessed by ELISA.
Challenge with peptide P3 is represented by the open symbols, whereas
peptide P4 is represented by the filled symbols. APC with the
irrelevant MBP peptide at 10 μM did not induce any IL-2 release
(broken line). (B) After 4 and 24 h, cells were
stained for expression of human TCRBV1 and fixed in 1% formaldehyde.
TCR37.33 cells were tightly gated on forward scatter/side scatter to
exclude the APC. TCR expression was tested in TCR37.33 incubated with
APC and the irrelevant MBP peptide 13–32 (solid line, mean
fluorescence intensity 97.8), peptide P3 (dotted line, mean
fluorescence intensity 8.76) or peptide P4 (dashed line, mean
fluorescence intensity 12.19). Peptides were used at 10 μM. The gray
line represents TCR37.33 stained with a rat anti human isotype control
(mean fluorescence intensity 5.8). The data are representative of at
least four different experiments.