Figure 3. IL2 production and conjugate formation of adaptively tolerant T cells with the P13.9 cell line as APCs.

A, Purified naïve (◆), adaptively tolerant (□), or pre-activated (Δ) T cells were stimulated with various doses of MCC peptide in the presence of irradiated APCs. The P13.9 cell line (MHC-II⁺, CD80⁺, ICAM1⁺) was used as the APC. The supernatant was collected after 38 h of culture, and IL-2 was assayed by ELISA. The data in A are all from one experiment of 2 performed.

B and C, The P13.9 cells were pre-pulsed with the indicated concentrations of MCC(88–103) peptide and the cells mixed with naïve (◆), tolerant (□), or pre-activated (Δ) T cells (B) for 30 min or pulsed with 1μM MCC(88–103) peptide and mixed for 5, 30, or 60 min (C). The percentages of MHC class II⁺ cells within the CD4⁺ T cell population were determined. The data shown in B and C are the averages from 2 experiments.

D, The P13.9 cells were pre-pulsed in the presence or absence of 1μM MCC (88–103) peptide and mixed with purified naïve, adaptively tolerant, or pre-activated T cells for 30 min in the presence or absence of anti-LFA1 mAb (1μg / 2 × 10⁵ cells) or anti-CD80 mAb (2μg / 2 × 10⁵ cells). The percentages of CD4⁺ and MHC class II⁺ conjugates were determined. The results shown are the means ± SD for three experiments. Values of p were calculated using a two-way ANOVA and a Bonferroni post hoc test. *, p < 0.05; **, p < 0.01; ***, p < 0.001. (the asterisk indicates a significant difference from untreated P13.9 with or without MCC).