lymphoid system 2 Flashcards
antigens are
any molecule that is recognized by cells of the adaptive immunity
- usually surface proteins of a pathogen
antibodies are:
glycoproteins in the immunoglobulin family that interact directly with antigens
- B lymphocytes>Plasma>antibodies
classes of antibodies
(Ig=immunoglobulin)
- IgE
- IgG
- IgA
IgE
- primarily in plasma
- in presence of allergies
IgG
- most common
- in the plasma
- neutralize antigens
IgA
- primary secretory immunoglobulin
- in saliva and milk
innate immunity
- immediate
- non specific
- physical barriers
- targets wide variety of pathogens
- neutrophils
- toll-like receptors (TLRs)
- natural killer cells (NKC)
- antimicrobial chemicals produced by leukocytes
antigen presenting cells include:
- macrophages
- dendritic cells in lymphoid organs
- thymic epithelial cells
stimulated phagocytosis
directed cell killing by innate immune cells
marginating compartment
compartments where diapedesis occurs as well as different locations on endothelial lining (step 3)
adaptive immunity
- specific
- mediated by lymphocytes and antigen-presenting cells
- has ability to remember specific pathogens (memory)
a molecule recognized by cells are called
antigens
antigens consist of
soluble molecules (proteins and polysaccharides)
immune cells recognize and react to
small molecular domains of the antigen known as antigenic determinants or epitopes (site of binding)
immune response can be
- cellular
- humoral
- both
cellular immune response is controlled by
lymphocytes
humoral immune response is controlled by
antibodies
characteristics of immunoglobulins
- heterotetomers bonded by disulfide bonds
- end terminal region is variable
- Fc region
heterotetomers of antibodies include
2 light chains and 2 heavy chains
IgG and IgA have the ability to
- bind specifically and neutralize viral/bacterial toxins
- agglutinate bacterial cells
- precipitates soluble antigens
NK cells activation
- antibodies bound to antigen on virus infected cells
- recognized by primitive lymphocytes
- activated to kill infected cell by releasing perforin and granzymes
Major Histological complex has
2 classes
MHC class I
- self antigen
- T cells recognize this and do not bind to the cells this marker is on
- presents on surface of nucleated cells
- is not presented on RBCs and platelets
MHC class II
- foreign antigen
- T lymphocytes recognize this marker, bind, and eliminate the marked cell
markers of T lymphocytes
CD4 and CD8
CD4 marked T cells
- are helper T cells
- bind to MHC class II presenting cells
- produce cytokines to differentiate B cells into plasma cells
- can become long lived memory T cells
- can help activate cytotoxic T cells
CD8 marked T cells
- are cytotoxic T cells
- trigger apoptosis in MHC class I (self) presenting cells that are infected
- activated by helper T cells (CD4) to help eliminate MHC II (toxic) presenting cells
T cell maturation
- occurs in thymus
- positive selection
- negative selection
positive selection
- first step in maturation
- occurs in cortex
- checks to see if T cells bind to MHC molecule presented
- if yes = survive and move to medulla (weak binding is good enough)
- if no = death - because if they cannot bind to MHC they cannot carry out their function
negative selection
- second step in maturation
- happens in medulla of thymus
- checks to see if T cells bind to MHC I
- if yes = cell dies
- if no = cell survived maturation and can leave thymus
what is diapedesis?
the passage of blood cells through the walls of the capillaries, typically accompanying inflammation
