Anti-Inflammatory Agents/pharmacology; CD4-Positive T-Lymphocytes/immunology; Graft vs Host Disease/prevention & control; Inflammation/prevention & control; Membrane Proteins/metabolism; Animals; Animals, Newborn; Apoptosis; Blotting, Western; CD4-Positive T-Lymphocytes/metabolism; Cell Differentiation; Cell Proliferation; Cells, Cultured; DNA-Binding Proteins/physiology; Female; Flow Cytometry; Forkhead Transcription Factors/genetics; Forkhead Transcription Factors/metabolism; Graft vs Host Disease/immunology; Graft vs Host Disease/metabolism; Humans; Inflammation/immunology; Inflammation/metabolism; Interferon-gamma/genetics; Interferon-gamma/metabolism; Interleukin-2/genetics; Interleukin-2/metabolism; Interleukins/genetics; Interleukins/metabolism; Membrane Proteins/genetics; Mice; Mice, Knockout; RNA, Messenger/genetics; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; T-Lymphocytes, Regulatory/immunology; T-Lymphocytes, Regulatory/metabolism; Transforming Growth Factor beta/genetics; Transforming Growth Factor beta/metabolism; Transplantation, Heterologous