Immunology Flashcards
CD4 cells are also known as?
Helper T cells
What roles do helper T cells play?
Release IL-2, IL-4, interferon gamma, and involved in delayed-type hypersensitivity (type IV, brings in inflammatory cells by chemokine secretion)
What is the main function of IL-2?
Maturation of cytotoxic T cells
What is the main function of IL-4?
B-cell maturation into plasma cells
What is another name for CD8 cells?
Cytotoxic T cells and suppressor T cells
What is the function of suppressor T cells?
To regulate CD4 and CD8 cells
What are the functions of cytotoxic T cells?
Recognize and attack non-self antigens attached to MHC class I receptors
What is responsible for the majority of liver injury due to HepB?
Cytotoxic T cells responding to viral gene products
Does cell-mediated immunity require AB’s?
NO
What are the effector cells in cell-mediated immunity?
Macrophages, cytotoxic T cells, natural killer cells
What kind of infections are associated with defects in cell-mediated immunity?
Intracellular pathogens (TB, viruses)
How does the intradermal skin test work?
Tests cell-mediated immunity. Takes 2-3 days
What stimulates B cells to become plasma cells?
IL-4 from helper T cells
What % of B cells become memory B cells which can be reactivated ?
10%
What type of antibody is secreted with first infection and with reinfection?
First infection- IgG
Reinfection- IgM
What types of MHC class I are there?
A, B, C
What type of T cell does MHC class I activate?
CD8
On what type of cells are MHC class I present on?
All uncleared cells
What types of MHC class II cells are there?
DR, DP, and DQ
What kind of T cell does MHC class II activate?
CD4 cells
On what type of cells are MHC class II present on?
Antigen-presenting cells (APCs)
What kind of cells are antigen-presenting cells?
Dendrites and monocytes
What is the purpose of antigen-presenting cells?
Activate helper T cells as they pass through lymph nodes AND stimulates antibody formation after interactions with B cells
How are viral infections recognized by the body?
Endogenous viral proteins are produced which are then bound to class I MHC —> proteins are presented on the surface of class MHC and recognized by cytotoxic CD8 cells
How are bacterial infections recognized and fought off by the body?
Endocytosis and proteins get bound to class II MHC molecules, which are presented on the cell surface and recognized by CD4 helper T cells —> CD4 cells activate the B cells which have already bound to the antigen —> B cells then produce antibody to that antigen and are transformed to plasma cells and memory B cells