Ch. 19 Flashcards
Three Levels of Immune Protection
- skin
- innate immune system
- adaptive immune system
each level increases aggressivity
The Skin & its associated organisms
skin = physical barrier to pathogens, mucus and lysozyme kill invading bacteria
Innate Immune System
Nonspecific responses, inflammation, complement system (fever)
Adaptive Immune System
very SPECIFIC responses, antibody-mediated immunity, cell-mediated immunity
dendritic cells present antigens - produces cellular repsonse or humoral response
Viruses
single/double strand of RNA/DNA (can’t repair) wrapped in proteins w/ attached sugars & maybe outer lipid bilayer; differ in reproduction modes & mutations
Influenza Viruses
single stranded RNA virus, A B and C strands (vaccine has 2 types of A and one B), can be distinguished by 2 surface glycoproteins (Hemagglutinin- HA and Neuraminidase-NA), receptor is sialic acid
antigenic shift- large scale changes
antigenic drift- small scale changes
SARS-CoV-2 Virus
Single stranded RNA virus, “Crown-like” viral surface, receptor is AC2
HLA (human leukocyte antigen) = MHC in humans
set of 9 genes (w/ different alleles) within MHC (major histocompatibility complex); allows for countless allele combos/haplotypes, 2 haplotypes per person (one on each chromosome 6)
plays an important role in organ transplantation
Antigen Processing
process where HLA glycoproteins (linked sugars that exend from cell surfaces) can recognize bacterial & viral proteins to mark them as targets for immune system
Class I- found on all cell types
Class II- found on antigen-presenting cells
Antigen Presenting Cells
cells that bind antigens with HLA glycoproteins
- macrophages
- B cells (or B lymphocytes)
- Dendritic cells (found where body contacts environment - skin & respiratory and digestive tracts)
How do Antigen-Presenting Cells work?
- Phagocytosis of microbial invader
- Antigens from dismantled invaded are attached to MHC self proteins
- MHC proteins and their attached antigens are displayed on macrophage surface
- Helper T cells recognize antigens, MHC proteins and binds to macrophage, itiating series of immune events
The Human Immune System
network of lymphatics (vessels) and lymph nodes (bean-shaped structures)
Lymph
fluid filling lymph ducts, carries macrophages and B and T lymphocytes
What organs are involved in production/maturation of immune cells
spleen & thymus, bone marrow
Macrophages
engulf bacteria & stimulate helper T cells to proliferate (mulitply) and activate B cells
Bone Marrow
T cells, B cells, and macrophages in the bone marrow & migrate in blood
T cells
mature thymus gland in small intestine and skin
cell mediated community (cytotoxic T cells attack cells directly)
B cells
released from lymphoid tissues (spleen and lymph nodes) and secrete antibodies
produce plasma and memory cells
Innate Immunity
immediate and generalized response attack within minutes
Toll-like receptors on macrophages and dendritic cells bind proteins to trigger innate immune response
Adaptvie Immunity
specific and slower attack (response time can take days), requires stimulation
Physical Barriers of Immunity
first line of defense (nonspecific defenses)
- unbroken skin
-mucus membranes & secretions
- waving cilia in respiratory tract
- flushing effect of tears, saliva, urination, diarrhea
Inflammation
central part of innate immune system, hostile environment for certain types of pathogens using phagocytes that engulf and destroy pathogens via phagocytosis
plasma accumulates to dilute toxins & bring in antimicrobial chemicals (increased blood flow)
Proteins in Innate Immunity
Complement system, collectins, cytokines
Mutations in the genes that encode these proteins lower resistance to infection
Complement System
plasma proteins that assist/complement several other defenses
puncture bacteria, dismantle viruses, activate mast cells to release histamine, attract phagocytes
Collectins
recognize differences between bacteria, yeasts, and some viruses from human cells
Cytokines- Colony-stimulating factors
stimulate bone marrow cells to produce lymphocytes, play roles in both innate and adaptive immunity
Cytokines- Interferons
antiviral; block viral replication, stimulate macrophages to engulf viruses, stimulate B cells to produce antibodies, attack cancer cells
Cytokines- Interleukins
control lymphocyte differentiation and growth, cause fever that accompanies bacterial infection
Cytokines- Tumor necrosis factor
stops tumor growth, releases growth factorws, stimulates lymphocyte differentiation, dismantles bacterial toxins and attacks cancer cells
Adaptive Immunity Characteristics
diversity, specificity, memory (responds faster w/ subsequent exposure)
Primary Immune Response: reaction to first exposur4e
Secondeary Immune Response: reaction to exposure using “memory” of firswt response
Humoral Immune Response- Adaptive Immunity
B cells produce antibodies in response to activation by T cells
Cellular Immune Response- Adaptive Immunity
T cells produce cytokines and activate other cells
Humoral Immune Response (antibody-mediated)
- antigen-presenting macrophage activates helper T cell
- Helper T cell activates B cell w/ matching cell surface receptors
- B cells divide to produce plasma cells and memory cells
Plasma Cells
secrete antibodies into blood that will recognize the antigen presented
Memory Cells
remain dormant until second exposure when they respond faster and more efficiently
Production of Antibodies
Antigens- Antigen-presenting cell (dendritic cell) - stimulates helper T cells- stimulates B cells OR Antigen to B cells
Antigen to B cells - proliferation- proliferation- memory cell and plasma cells
Is the humoral immune response polyclonal or monoclonal?
polyclonal; different antibody proteins recognize and bind to different features of foreign cells
Antibody Structure
4 polypeptide chains (2 long&heavy and 2 shorter&light chains)
Constant region of each chain is similar
Variable region of each chain is diverse
Antigen binding sites: where antigen binds
Idiotypes: sites in direct contact w antigen
Epitope: portion of the antigen contacting the antibody
What are the functions of antibodies?
inactivate pathogen/neutralize the toxin, clump pathogens to make it more visible for macrophages, activate complement system boosting innate immune response
Antibodies are also called
immunoglobins (Ig)
What is the most abundant antibody?
IgG- in blood plama and tissue fluid; passes to fluid
How does the body create antibody diversity?
V (variable), D (diversity), J (joining) recombination creates new versions of antibody proteins and recognizes different responses
Types of T Cells
Helper T cells (many functions), Cytoxic T cells(killer T cells), Regulatory T cells (dampen immune response)
Cytotoxic T Cells
Have CD8 antigens and mediate final killing of cancer cells
The Cell-Mediated Immune Response
MHC I -> CD8 _+T cells = helper T cells)
MHC II -> CD4 (+ T cells = killer T cells)
What is the role of helper T cells in the humoral immune response?
recognize antigens presented by macrophages and stimulate B cells to produce antibodies (AIDS, low CDH cell count = high antibody or cell immune response)
What is the role of helper T cells in the cellular immune response?
secrete cytokines and activate cytotoxic T cells
Death of a Cancer Cell
- cytotoxic T cell binds to cancer cell
- Perforin breaks cancer cell apart
- T cell has lysed cancer cell
Is MHC I an antigen presenting cell or all cell-presenting cell
all cells presenting cells
Is MHC II an antigen presenting cell or all cell-presenting cell
antigen-presenting
Function of Macrophage
presents antigens and performs phagocytosis
Function of dendritic cell
presents antigens
Function of mast cell
releases histamine in inflammation and allergy mediators
Function of B cells
matures into antibody-producing plasma cell or into memory cell
Function of T cell Helper
recognizes nonself antigens presented on dendritic cells, stimulate B cells to produce antibodies, secretes cytokines, activates cytotoxic T cells
Function of T cell Cytotoxic
attack cancer cells and cells infected w viruses upon recognizing antigens
Function of regulatory cells
suppresses immune response
Function of neutrophil
attacks bacteria
How is SCID an inherited immune deficiency?
severe combined immune deficiences (SCID) impacts both humoral and cellular immunity due to lack of mature B cells and/or T cells
How does HIV affect the body?
infects macrophages and helper T cells by binding to CD4 and CCR5 coreceptors
virus replicates then bursts out of helper T cells (killing it)
low helper T cells = low B cells
How HIV infects
- virus binds receptors on plasma membrane and enters. enzymes remove proteins around viral DNA
- Reverse transcriptase forms complementary DNA to viral DNA
- new DNA strand is template for complementary strand
- double stranded DNA incorporated into host cell genome
- viral genes transcribed into mRNA
- mRNA translated to proteins
- capsids surround new viral, RNA genomes
- new viruses bud from host cell
What points of infection do drugs inhibit?
entry of virus into T cells, replication of viral genetic material, processing of viral proteins
Anti-HIV Drugs (cART): reverse transcriptase inhibitor
blocks copying of viral RNA into DNA
Anti-HIV Drugs (cART): protease inhibitor
blocks shortening of certain viral proteins
Anti-HIV Drugs (cART): fusion inhibitor
blocks ability of HIV to bind a cell
Anti-HIV Drugs (cART): entry inhibitor
blocks ability of HIV to enter a cell
What does the CCR5 gene do?
as genome storage, it encodes for a receptor protein on the cell membrane (coreceptor for HIV)
CCR5 gene
individuals homozygous for a 32-base deletion (mutation) of CCR5 are resistant to infection
What is an autoinflammatory disease?
overreaction of the innate immune response causing inflammation
What is an autoimmune disease?
overreaction of the adaptive immune response causing inflammation and production of autoantibodies that attack specific “self” cells and tissues
What is an allergy?
immune system to a substance (allergen) that does not actually present a threat
How does the body react to an allergy?
humoral & cellular immunity, IgE antibodies made and bind to mast cells, mast cells release allergy mediators (histamine and heparin) to cause symptoms
allergens activate helper T cells to release cytokines
What are the stages of a cell after initial exposure with an allergen?
B cell is activated - antibody secreting plasma cell - antibodies attach to mast cell through IgE receptor
What are the stages of a cell after subsequent exposure to an allergen?
allergens combine w mast cell then mast cell releases allergy mediators (histamines & other chemicals cause allergic reaction)
Rh Incompatibility
occurs when an Rh- (no Rh antigen) mother has an Rh+ (has Rh antigen) child
First Rh incompatible pregnancy
fetal cells recognized as foreign, mother’s immune system attacks fetal cells, produces mild reaction w/ few antibodies present
Rh+ cells enter mother’s bloodstream then she produces Rh+ antibodies
Second Rh incompatible pregnancy
foreign antigen stimulates woman’s body to make antibodies- anti-RH+ antibodies bind antigen on RBC of fetus - destruction of fetal blood cells
Vaccines
based on memory, inactive, disabled part of pathogen that stimulates immune system to alert B cells to produce antibodies
What are monoclonal antibodies (MAb)
detecting and targeting one particular antigen, preserving specificity and amplifying antibody type, made directly from individual cells from people who have been immunized against infectious disease
Polyclonal antibodies
detect and target multiple antigens
Example of how cytokines boost cellular immunity
Interleukin-2: kidney cancer recurrence
Transplantation Type: autograft
from one person to self
Transplantation Type: isograft
from identical twin
Transplantation Type: allograft
members of the same species
Transplantation Type: xenograft
from another species
How is a successful transplant determined?
depends on HLA matching between donor and recipient (best chance for match is between related individuals)
Graft Rejection
immune system reacts to grafted tissue recognized as foreign by trying to destroy it (immunosuppressant drugs inhibit production of antibodies and T cells that attack transplanted tissue)
