Chapter 4 - Immunology Flashcards
What is IL-4? what does it do?
Released by CD4 helper T cell
Causes B-cell maturation into plasma cells
What is IL-2? what does it do?
Released by CD4 helper T.
Causes maturation of cytotoxic T cells.
Involved in delayed hypersensitivity. (brings in inflammatory cells by chemokine secretion)
What do Th1 helper T-cells do? examples?
Predominant release of proinflammatory cytokines (IL-2, INF-gamma). Cell mediated responses against intracellular bacteria and protozoa.
Work with cytotoxic CD8 and macrophages.
Overactivation - Type 4 delayed-type hypersensitivity - Type 1 DM
(IL-2 involved in B cell maturation to plasma cells)
(Cell mediated responses involved in TB, viruses, intradermal skin test)
What do Th2 helper T-cells do? examples?
Predominant release of anti-inflammatory cytokines (IL-4 inhibits macrophages).
Humoral response against extracellular parasites - helminths.
Overactivation - Type 1 hypersensitivity - atopy and allergic responses (IL-4 - B-cell - IgE - mast cell release of histamine, serotonin)
(IL-4 also involved in B cell maturation into plasma cell)
What do Suppressor T cells (CD8) cells do?
Regulate CD4 and CD8 cells
What do cytotoxic T cells (CD8) do?
(Maturation by IL-2)
Recognize and attack non-self antigens attached to MHC- class 1 receptors (eg viral gene products)
What does an intradermal skin test look for?
cell-mediated immunity
What types of infections are associated with defects in cell-mediated immunity?
intracellular pathogens (TB, viruses)
(why TB tested by intradermal skin test)
What effect can nucleotides have on the immune response?
increase T-cell mediated immunity
(intradermal skin test, TB, viruses)
What is the first step in T-cell and B-cell activation?
alloantigen binds to antigen specific receptors: TCR (t-cells) or surface IgM (B-cells).
What is the second step or costimulatory signal required for T-cell and B-cell activation?
IL-1 released by antigen presenting cell.
CD-41 helper T-cells release IL-2, IL-4, and IL-5 which provide help for CD81 T-cells and for B-cell activation.
(IL-1 - fever, IL-2 - cytotoxic T cell maturation, IL-4 - B cell to plasma cell)
What does MHC class I (A, B, and C) do? Where is it present? Structural makeup? What is it a target for?
CD8 cell activation. On all nucleated cells. Single chain with 5 domains. Its a target for cytotoxic T-cells.
(Cytotoxic T cells matured by IL-2, CD8 can be cytotoxic or suppressor. Cytotoxic cells recognize non-self antigens, like virus, on MHC1 presenting cells)
What does MHC class II (DR, DP, and DQ) do? where is it located? structural makeup?
CD4 cell activation. Present on B-cells, dendrites, monocytes, and antigen presenting cells. 2 chains with 4 domains each. Activator for helper T-cells. Stimulates antibody formation.
How are viral infections recognized by immune system?
Endogenous viral proteins are produced, bound to class I MHC, go to cell surface, recognized by CD8 cytotoxic T-cells.
How are bacterial infections recognized by immune system?
endocytosis, proteins bound to class II MHC molecules, go to cell surface, recognized by CD4 helper T-cells -> B cells already bound to antigen are then activated by CD4 helper T-cells. They then produce the antibody to that antigen and are transformed to plamsa cells and memory B-cells
Do natural killer cells require MHC?
Do not require MHC, previous exposure, or antigen presentation. Not considered T or B. Recognize lack of self MHC. Cancer surveillance.
What is IgM?
Initial ab made after exposure to antigen. Largest Ab. 5 domains, 10 binding sites.
What is IgG?
Most abundant antibody in the body. responsible for secondary immune response. Can cross placenta - protection in newborn period.
What is IgA?
Found in secretions. Peyers patches in gut - prevents microbial adherence and invasion in gut; and in breast milk - additional immunity in newborn.
What is IgD?
membrane-bound receptor on B-cells (antigen receptor)
what is IgE?
allergic reactions, parasite reactions
What antibodies are opsonins?
IgM and IgG. Fix complement. 2 IgG’s or 1 IgM
What does the variable region in an antibody do?
antigen recognition
What does the constant region in Ab do?
Recognized by PMN and macrophages. Fc fragment does not carry variable region.
