they are initiated in secondary lymphoid tissues by antigen-bearing dendritic cells and T cells
how do T cells recognize antigens?
T-cell receptors recognize peptide antigens bound to human cell-surface molecules, called MHC molecules
what do MHC class I molecules do?
they present antigens of intracellular origin (e.g. viruses) to CD8 T cells (cytotoxic T cells)
what do MHC class II molecules do?
they present antigens of extracellular origin (e.g. engulfed bacterium) to CD4 T cells (helper T cells)
where are MHC class I molecules found?
in all cells
where are MHC class II molecules found?
in dendritic cells, macrophages, and B cells
what are cells that carry antigen-MHC complexes called?
Antigen presenting cells
what are cells that carry antigen-MHC class II complexes called?
professional antigen-presenting cells
what are the two types of activated T helper cells and what do they do?
TH1 cells release cytokines and activate macrophages
TH2 cells release cytokines and activate B-cells
what is the function of the variable receptor region of an antibody?
it determines specificity for different antigens (pathogens) --> each antigen is recognized by antibodies with specific corresponding V-regions. V-regions are the N-terminal regions.
What is the function of the constant receptor region of an antibody?
determines type and function (but not specificity) of antibodies. Contains binding sites for cell-surface receptors on phagocytes and inflammatory cells (= mediate binding to the inflammatory cells). --> antibodies therefore serve as "bridges" between antigens and the inflammatory cells. There are five different isotypes (classes) of antibodies, and they differ in their constant regions
true or false? each lymphocyte (B cells and T cells) expresses T cell receptor (TCR) or immunoglobulin (Ig) of a single specificity.
what is humoral immunity?
immunity mediated by antibodies
what are the five classes of immunoglobulins?
IgA, IgD, IgE, IgG, and IgM
what is the difference between the different classes of immunoglobulins?
they differ in their heavy chain constant regions, and have different functions when released as antibodies
what are the two main mechanisms by which an antibody can inhibit an antigen?
neutralization and opsonization
when exposed to an antigen, activated B cells develop into what two cell types?
plasma cells and memory cells
how one develops acquired immunity can be divided into two categories. These two categories can further be divided into two categories. Explain this.
one can develop acquired immunity naturally (e.g. antibodies are passed to fetus through placenta) or artificially (e.g. through vaccination). It can also be developed actively (e.g. through infection) or passively (e.g. antibodies that have been produced by another animal or in vitro are given to an animal).
what is the difference, time-wise, between passive adaptive immunity and activity adaptive immunity ?
passive immunity is short-lived and active immunity is generally long-lived.
how are allergies caused?
they occur when IgE antibodies are made against harmless substances (pollen, dust, foods).
These IgE antibodies bind and acitvate mast cells, which then produce pro-inflammatory cytokines that induce inflammation (sneezing, swelling of tissues, redness of eyes).
immuno 007 introduction to adaptive immunity part 1 (T-cell B-cell MHC antibody memory cells va
immuno 007 introduction to adaptive immunity part 1 (T-cell, B-cell, MHC, antibody, memory cells, vaccination, immunity, allergies) #12