innate and adaptive immunity Flashcards
what do cellular elements of blood and immune system arise from
pluripotent stem cells in the bone marrow
what are some diseases caused by viruses in humans
small pox, red measles, german measles (rubella), and chicken pox
what do the early phases of the host response depend on
innate immunity
what does innate immunity utilize to recognize common features of pathogens
invariant receptors
what differentiates innate immunity from adaptive immunity
innate immunity is present in everyone at all times and does not decrease with repeated exposure to a given pathogen
what generates adaptive immune responses
clonal selection of lymphocytes
what does adaptive immunity lead to
immunologic memory which confers lifelong protective immunity to reinfection by the same pathogen
when does innate immunity occur
immediate 0-4 hours
when does early induced innate response occur
4-96 hours
when does adaptive immune response occur
after 96 hours
what are the major cells of innate immunity
macrophages, granulocytes, mast cells, dendritic cells, NK cells
what are the major cells of adaptive immunity
- B and T cells
-NK cells and plasma cells
how does infection trigger an immune response (mechanism)
-bacteria trigger macrophages to release cytokines and chemokines
- vasodilation and increased vascular permeability causes redness, heat, and swelling
- inflammatory cells migrate into tissue releasing inflammatory mediators that cause pain
how do dendritic cells initiate adaptive immune response (mechanism)
- immature dendritic cells reside in peripheral tissues
- dendritic cells migrate via lymphatic vessels to regional lymph nodes
- mature dendritic cells activate naive T cells in lymphoid organs such as lymph nodes
what do infectious agents have to overcome to establish infection
host defenses
how often does infectious disease occur
infrequently
what is the first barrier against most microorganisms
epithelial surfaces
what are the mucosal epithelial cells that provide a barrier and innate immunity
-goblet cells
-peristalsis in GI tract
-Paneth cells
-intraepithelial lymphocytes
what do goblet cells do
secrete mucus, glycoproteins that forms a dense, protective covering for the entire epithelium
what does peristalsis in the GI tract do
moves food and potential pathogens, while ciliated epithelial cells in the upper respiratory tract capture inhaled potential pathogenic particles and expel them through their beating motion
what do paneth cells do
produce anti microbial peptides, lectins and cytokines
what do intraepithelial lymphocytes to
contain various T cells
describe mucosal immunity
proactive and constantly making adaptive immune responses against microbes
what type of immunity is mucosal immunity
INNATE
does mucosal immunity activate inflammation
no
what does mucosal immunity do
contribute to the frequency with which gut epithelial cells are turned over and replaced
describe type 1 mucosal surface and what does it express
covered by simple epithelium. expresses a polymeric Ig receptor (pIgR) that allows dimeric IgA to access the lumen
where are type 1 mucosal surfaces found
intestine, lungs, uterus
describe type 2 mucosal surfaces
covered by stratified squamous epithelium that provides a physical protective barrier
where are type 2 mucosal surfaces found
oral cavity, vaginal cavity
what is the response to bacteria adherence to epithelium
normal flora, local chemical factors, phagocytes
what is the response to local infection, penetration of epithelium
wound healing induced antimicrobial proteins and peptides phagocytes, and complement destroy invading microogranisms
what is the response to local infection of tissues
complement, cytokines, chemokines, phagocytes, NK cells, activation of macrophages, dendritic cells to migrate to lymph nodes to initiate adaptive immunity, blood clotting helps limit spread of infection
what are the 3 types of mucosal epithelial cells in host defense
-villus type (GI tract)
- ciliated epithelium (nose URT)
- exocrine glands (ductal cells)
describe the outer mucus layer
-non sterile (bacterial habitat)
- microbes use mucin carbohydrates for energy
- less dense
describe the inner mucus layer
relatively sterile (free of bacteria)
-rich in antimicrobial molecules
- firmly attached
describe the mucus layer in small intestine vs large intestine
small intestine- only outer loose layer
large intestine- outer loose and inner layer
what is the inductive site
where immune system is breached and the process starts
what is the effector site
where the innate immune response starts
where does clonal selection and expansion take place
the germinal center of the lymph node
what is the mechanism of clonal expansion
- a single progenitor cell gives rise to a large number of lymphocytes w different specificity
- removal of potentially self-reactice immature lymphocytes by clonal deletion
- pool of mature naive lymphocytes
-proliferation and differentiation of activated specific lymphocytes to form a clone of effector cells
what is the variable region of the antibody molecule
2 light chains
what is the constant region of the antibody molecule t
the heavy chain
what joins the antibody
the joining region
what joins the light chains
cysteine bridges
what is the diversity of lymphocyte antigen receptors generated by
somatic gene-segment rearrangements
where is the Kappa light chain gene cluster located
on Cs2
where is the lambda light chain gene cluster located
on Cs 22
what makes up the heavy chain gene and where are they located
alpha, beta, epsilon, gamma and mu on Cs 14
how many different light chains are ther
290
how many different heavy chains are there
13,800
how many different binding specificities are there
4,002,000
what does junctional diversity do
addition or removal of nucleotides between different gene segments increases specificity of the variable region 10^10
what are antigens
molecules recognized by the immune response
what are epitopes
regions within antigens that antigen receptors bind
how do T cell recpetors recognize and bind antigens
-antigen is broken down into peptide fragments
-the epitope binds to an MHC molecule
- T cell recptor binds to a complex of MHC molecule and epitope
what do antibodies do with bacterial toxins
neutralization -> ingestion by macrophage
what do antibodies do with bacteria in ECS
opsonization -> ingestion by macrophage
what do antibodies do with bacteria in plasma
complement activation -> lysis and digestion
what are MHC molecules
large locus of DNA that encodes genes for cell surface receptors that are essential for the adaptive immune response
what do MHC1 molecules do
collect peptides derived from proteins synthesized in the cytosol from viral infections and display those peptides on the cell surface
what do MHC 2 molecules do
bind peptides derived from proteins in intracellular vesicles and display those on the cell surface
how many transmembrane spanning domains do MHC class 1 and class 2 molecules have?
MHC 1 - single domain
MHC 2- 2 spanning domain
what MHC receptors do viral infections use
MHC class 1
what lymphocytes do MHC class 1 receptors use
cytotoxic T cell
what lymphocytes do MHC class 2 recptors use
helper T cell
what is the mechanism of action for MHC class 1
-virus infects cell
-viral proteins synthesized in cytosol
-peptide fragments of viral proteins bound by MHC class 1 in ER
- bound peptides transported by MHC class 1 to the cell surface
- cytotoxic T cell recognizes complex of viral peptide with MHC class 1 and kills infected cell
what is the mechanism of action for MHC class 2 with bacteria
- bacterium infects macrophage and enters vesicle, producing peptide fragments
-bacterial fragments bound by MHC class 2 in vesicles
-bound peptides transported to surface by MHC class 2 - helper t cell recognizes complex of bacterial peptide with MHC class 2 and activates macrophage
what is the mechanism of action for MHC class 2 with antigens
- antigen bound by B- cell surface receptor
- antigen internalized and degraded into peptide fragments
- fragments bind to MHC class 2 and are transmitted to the surface
- helper t cell recognizes complex of antigenic peptide with MHC class 2 and activates B cell
