Induction of tolerance to male bone marrow and spleen cell engraftment by HY peptide. (A) Intranasal administration of HYAbDby peptide facilitates engraftment of syngeneic male bone marrow grafts. Appearance of B6.Thy1.1 male T cells in PBL of female B6 (Thy1.2) recipients pretreated intranasally with 3 × 100 μg HYAbDby peptide 10 days before irradiation (200 R) and with intravenous injection of 5 × 106 B6 Thy1.1 male bone marrow cells. FACS profiles of PBLs stained for each Thy1 allele, 2 weeks after bone marrow transplantation, of single representative PBS-treated mice (i), peptide-treated mice (ii), and percentage of donor-derived Thy1.1+ T cells in PBLs from recipient mice, PBS-treated, n = 6 (iii), and peptide-treated, n = 6 (iv) at 2, 4, and 6 weeks after bone marrow injection. Each symbol represents data from an individual mouse. Significant differences of peptide-treated from PBS control: P = .0021 at 4 weeks, P = .0028 at 6 weeks. (B) The in vivo cytotoxicity assay: FACS analysis of CFSE-label and tetramer. A mixture of male and female spleen cells labeled with different concentrations of CFSE (male, low; female, high) were injected intravenously into recipient mice: a PBS-treated naive female (i-ii) and an HYAbDby peptide–pretreated female (iii-iv). PBLs taken 14 days later were stained with CD8 and tetramer and examined by FACS. Panels i and iii show the remaining CFSE-labeled donor cells; panels ii and iv show tetramer-positive cells of recipient origin. (C) Intranasal HYAbDby peptide prolongs survival of syngeneic male spleen cells. B6 females were given intranasal PBS (n = 8) or 3 × 100 μgHYAbDby peptide (n = 8). Ten days later they received intravenously a mixture of differentially CFSE-labeled male and female splenocytes, and sequential PBL samples were analyzed as described. Panels i and ii show ratio of male to female cells, panels iii and iv show frequency of HYDbUty tetramer-positive cells within CD8+ T-cell population. Each symbol represents an individual mouse.
