Administration of donor apoptotic cells regulates the indirect T cell responses.

<p>A) Allo-Ag presentation and ELISPOT assays of splenocytes from B6 mice reconstituted (or not, control) with 1H3.1 CD4 T cells and then injected i.v. with B6 (control) or BALB/c apoptotic splenocytes (alone or with agonistic CD40 mAb), or with BALB/c splenocytes alive. Fourteen days later, splenocytes from the host B6 mice were cultured alone or with the BALB/c peptide IEα_52–68 during 72 h for assessment of T cell proliferation by [³H]TdR incorporation, or for 36 h in ELISPOT plates for quantification of IFN-γ and IL-10 secretion. Each group included 6 mice. B) Analysis by FACS of the percentage of CD4 1H3.1 T cells (Thy1.1⁺) expressing FoxP3 in the spleen of host B6 mice (Thy1.2⁺) 14 days after receiving i.v. B6 (control) or BALB/c apoptotic splenocytes, or BALB/c splenocytes alive. Numbers indicate percentages of cells. One representative of 6 individual experiments is shown. * p<0.01. C) Assessment by in vivo killing assays of the Ag-specific lytic activity of B6 mice reconstituted with 2C CD8 T cells and treated (day 1) with 10⁷ MHC-I^−/− B6 apoptotic or alive splenocytes loaded (or not) with the H2K^b-retricted SYGL peptide. Mice were challenged (or not) on day 6 with SYGL plus IFA (i.p.). On day 9, mice were i.v. injected with a 1/1 mixture of CFSE^hi BALB/c×B6 (F1) (target) and CFSE^lo B6 (control) splenocytes. Five h later, the ratio of CFSE^hi vs. CFSE^lo cells in the spleen was determined by FACS. Numbers indicate percentages of cells. The specific lysis was calculated and is shown as the mean±SD of 3 mice per group.