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what are the major functions of adaptive immunity?
- recognize things that are foreign to the body (no self)
- respond to foreign material
- remember the foreign invader upon subsequent exposure
what are antigens?
self and non self molecules are elicit an immune response
what is an epitope?
site of the Ag that reacts with its specific antibody of T cell receptor
MHC (major histocompatibility complex) genes
- set of genes that code for proteins involved in self/nonself recognition
- important for the activation of T cells
what are human MHC genes called?
human leukocyte antigen (HLA) complex
what is the difference between MHC class 1 and class 2?
class 1 is found on all nucleated cells and class 2 is only found of professional antigen presenting cells (APC) such as macrophages, DC, B cells
membrane bound protein complexes where antigens bind in a groove on the surface of each complex
how are antigens presented by MHC class 1?
MHC class 1 binds to antigenic peptides that come from INSIDE the cell and then "presents" the antigen to CD8+ T cells
how are antigens presented by MHC class 2?
MHC class 2 binds to antigenic peptides that come from OUTSIDE the cells and then "presents" the antigen to CD4+ T cells
T cell receptor (TCR)
- cell surface glycoproteins that interact with specific peptide MHC
- forms a complex with CD3 proteins which transmit signals from the TCR into the cell
how can a T-cell become specific?
each T cell expresses many copies of the same TCR on its surface what recognizes a specific peptide (MHC complex)
How are T cells activated? (2 signals)
- 1.TCR binding to peptide MHC
- 2. Costimulatory signals provided by CD28 interaction with B7 proteins
what are B7 proteins and When are B7 proteins unregulated?
they are proteins on the antigen presenting cell that signal to the T cells that the cell is infected. B7 proteins are unregulated in response to microbial stimuli
what are the 3 consequences of T cell activation?
- 1. T cell multiplies - clonal expansion
- 2. CD4+ T cells become T helper cells and B cells make antibodies
- 3. CD8+ T cells become cytotoxic T cells (CTL) and kill target cells
what are superantigens?
bridge class II MHC molecules on APCs (antigen presenting cells) to T-cell receptors in the absences of a specific antigen in the MHC-binding site
what are the results of super antigens?
results in the activation of many T cells with different antigen specificites AND leads to the overproduction of pro inflammatory cytokines
what is cellular immunity?
based on the action of T cells
what is humoral immunity
based on action of antibodies
B cell Recpetor (BCR)
b cells recognize antifesn through the B cell receptor
in most cases, B cell activation also requires 2 signals:
- 1. BCR binding to SOLUBLE antigens
- 2. Cytokines made by T cells
activation of B cells induce what response
activation results in production of antibodies
what are antibodies?
glycoproteins that are produced and secreted by plasma cells
where are antibodies found?
found in blood serum, tissue fluids, and mucosal surfaces of vertebrate animals
what do antibodies do?
recognize and bind the antigen that caused its production
what are the 2 regions of an antibody structure?
- variable region - Ag binding domain
- constant region - binds to antibody receptors on the surfaces of cells
what are the 5 different classes of antibodies?
- IgG- most common, can cross placenta
- IgM - complement activation
- IgA- tears, saliva breast milk
- IgD - part of BCR
- IgE - major Ig in allergy
what are the 5 actions of antibodies?
- complement fixation
what are the hallmarks of adaptive immunity?
- discrimination between self and non-self
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