Lymphocytes V Flashcards
How do thymus dependent antigens contribute to class switching and immunologic memory?
Through direct contact of B cells with Th cells (CD40-CD-40 ligand interaction) (p.198)
Where do CD4+ T cells become helper T cells?
In the lymph node (p.195)
Where do helper T cells become activated by IL-12 to form Th1 cells?
In the lymph node (p.195)
Where do helper T cells become activated by IL-4 to form Th2 cells?
In the lymph node (p.195)
What cytokine induces Th1 cell production in the lymph node?
IL-12 (p.195)
What cytokine induces Th2 cell production in the lymph node?
IL-4 (p.195)
Where does T cell positive selection occur?
In the thymic cortex (p.195)
Where does T cell negative selection occur?
In the thymic medulla (p.195)
What is positive selection?
Selection of T cells expressing TCRs that are capable of binding surface self MHC molecules will survive (p.195)
What is negative selection?
Apoptosis of T cells that express TCRs with high affiinity for self antigens (p.195)
Name the three types of antigen presenting cells.
Dendritic cells, macrophages, B cells (p.196)
What is the only type of APC that can activate a naiive T cell?
Dendritic cells (p.196)
What is required for T cell activation, for B cell activation, and for class switching?
Two signals (p.196)
What are the four steps in naiive T cell activation?
1.) foreign body is phagocytosed by a dendritic cell; 2.) foreign antigen is presented on MHC II and recognized by TCR on Th (helper) cells. Antigen is presented on MHC I to Tc cells. This is signal 1; 3.) A costimulatory signal is given via the interaction of B7 and CD28 (signal 2); 4.) Th cell activates and produces cytokines. Tc cell activates and is able to recognize and kill a virus infected cell (p.196)
