The percentage of CD8+ T cell to CD4+ T cells in the white matter of the human brain is - 2:1 5:1 3:1 O 4:1

1.Label the following figure that shows the sequence of events by which cytotoxic T cells destroy virus-infected cells.

Determine if the following description should be categorized as Humoral Immunity (B-cell activity), Cellular Immunity (T-cell activity), or both (B & T-cells perform this activity). 1. Can create antibodies 2. Can destroy pathogens by secreting perforins 3. Is activated by a T-helper cell 4. Undergoes clonal selection 5. Has the ability to stop clonal selection 6. Must have an APC (antigen presenting cell) to be activated 7. Can be activated by pathogen in circulation 8. Migrates around the body in the lymph 9. Can create a tag of MHC proteins to alert body of infection 10. Creates memory cells to recognize the pathogen in the future 11. Stimulated by MHC class 2 APC cells only 12. Can activate the second line of defense by secreting antibodies

True or false: 1. Highly proliferative centroblasts are located in the light-zone rather than the dark zone of the germinal center 2. All memory cells (central memory, effector memory, tissue-resident) have equivalent tissue-homing capacity 3. Effector T cells home to sites of infection through action of tissue-specific chemokines.   4. The differentiation fate of CD4 T cells is pre-determined before activation.