Roles of TNF-α and MHC class I peptide complexes in reversal of diabetes in NOD mice. (a) Effect of TNF-α on the survival of spleen cells derived from a control C57 mouse or from untreated or successfully treated NOD female mice. (b) Effect of TNF-α treatment of splenocytes from diabetic NOD mice on the adoptive transfer of disease and the inability of splenocytes from successfully treated NOD mice to transfer disease. Young male NOD mice were irradiated and then injected with diabetic NOD female splenocytes either immediately after their isolation (left panel, dashed lines) or after incubation for 24 hours in the absence (left panel, solid lines) or presence (middle panel) of TNF-α (20 ng/ml); alternatively, four irradiated hosts each received splenocytes from a different NOD donor with long-term normoglycemia restored by CFA and C57 spleen cell injections (right panel). (c) Flow cytometric analysis of the percentages of CD8⁺CD45RB^high, CD8⁺CD62L⁺, and CD8⁺CD95⁺ cells among splenocytes of mice from various treatment groups. Diabetic NOD females were implanted intraperitoneally with alginate-encapsulated C57 islets. They then received no further treatment (group A), a single bilateral injection of CFA only (group B), or CFA treatment plus biweekly intravenous injections of splenocytes from normal C57 mice (group C), β₂M^–/–, TAP1^–/– C57 mice (group D), or MHC class II^–/– C57 mice (group E). Shaded bars represent C57 control mice (group F) or NOD mice that exhibited normoglycemia and disease reversal after removal of alginate-encapsulated islets (groups C and E); open bars represent untreated NOD mice (group A) or NOD mice subjected to treatments that did not result in disease reversal (groups B and D).