article 6 gamma interferon 6 priority journal 6 tumor necrosis factor alpha 6 Animals 4 CD4-CD8 Ratio 4 CD4-Positive T-Lymphocytes 4 CD4/CD8 4 Cell Proliferation 4 Chronic stress 4 Cytokines 4 Female 4 Interferon-gamma 4 Interleukin-2 4 Killer Cells, Natural 4 Mice 4 Mice, Inbred BALB C 4 Restraint, Physical 4 Stress, Psychological 4 T-Lymphocytes 4 Tumor Necrosis Factor-alpha 4 animal cell 4 animal experiment 4 animal model 4 cellular immunity 4 chronic stress 4 controlled study 4 female 4 interleukin 2 4 nonhuman 4