Figure 3. T Cell Differentiation and Tissue Infiltration after Immunization with Suprathreshold or Subthreshold Peptide Ligands.

(A and B) OT-I T cells were adoptively transferred into C57BL/6 mice, and infection with Lm-Q4R7 or Lm-Q4H7 followed. (A) Representative flow-cytometry plots of SLEC and MPEC cells at days 6, 7, and 8 after infection. Numbers on the axes represent the log10 of fluorescence.

(B) Total splenic OT-I T cell numbers of SLEC and MPEC cells at day 6 after infection. Representative data are from two separate experiments; n = 5 mice per peptide; statistical analysis was performed with an unpaired two-tailed Student’s t test. Error bars denote SEM.

(C–F) T cell infiltration and diabetes induction mediated by VLA-4 upregulation on proliferating T cells. CFSE-labeled congenic OT-I T cells (5 × 10⁶⁾ were injected into RIP-OVA recipients, and peptide immunization and LPS followed. (C) Surface expression of VLA-4 and CFSE dye dilution on LN T cells was determined at day 3. Numbers on the axes represent the log10 of fluorescence. Representative data are from two separate experiments; n = 4 mice per peptide. (D) Representative immunohistochemistry for CD8 (yellow), insulin (red), and DAPI (blue) on pancreatic sections taken 3 days after immunization; images are magnified 40× (n = 3). (E and F) Mice were treated with anti-VLA-4 (500 μg, clone PS2) or isotype control (500 μg, IgG2b) at days 0 and 2. (E) Urine glucose (n = 8) and (F) immunohistochemistry (n = 3) were examined at day 4.