immune system p.III Flashcards
cellular (cell-mediated) immune response
antigen presenters for T cell maturation are:
- dendritic cells
- macrophages
- B cells
t cells must recognize self + nonself and form clones like in B cells but with different classes
t cell clones: helper T cells
circulate through body to recruit other immune cells
interacts with B cells and push them into rapid clone production and signal for antibody production to begin
helper T cells release lymphokines that
act indirectly to rid body of antigens by
- stimulating cytotoxic T cells + B cells to grow and divide
- attracting other types of protective WBCs in the area
- enhancing ability of macrophages to engulf, destroy microorganisms
t cell clones: cytotoxic T cells
specialize in killing virus-infected, cancer, or foreign graft cells
do this by binding to them and inserting toxin perforin into invader cell membrane
target cell ruptures and cytotoxic T cell attacks others
t cell clones: supressor/regulatory T cells
release chemicals to supress activity of T + B cells
vital for ending immune response after antigen destructure so no autoimmune stuff’
few members of each clone are memory cells
organ transplants + rejection
for those w/ end-stage heart disease or kidney disease organ transplants are desirable
may compromise immune system tho’
4 types of grafts
autografts
tissue transplanted from one site to another
on the same person
ideal + sucessful w/ adequate blood supply + no infection
isografts
tissue grafts from a genetically identical
person (identical twin)
ideal + sucessful w/ adequate blood supply + no infection
allografts
tissue taken from individuals that are not
genetically identical but belong to the same species
used from tissue/organs of recently dead people
ABO + other antigens of donor + recepient must be matched at least 75% but is hard to find in non-related ppl
xenografts
tissue taken from a different animal species
whole organs are never successful, but pig heart valves work
graft preventative measures
immunosupressive therapy is given after surgery to prevent rejection
examples of immunosupressive therapy
corticosteroids for less inflammation
cytotoxic drugs
radiation therapy
immunosupressor drugs
these kill rapidly dividing cells (lymphocytes) and have major side effects
cause patient to be very exposed to bacteria + viruses
allergies/hypersensitivities
abnormally vigorus immune responses where immune system causes tissue damage due to autoimmune issues
most common type ois immediate hypersensitivity
allergen
antigen that triggers hypersensitivity
immediate hypersensitivity
triggered by release of histamine due to IgE binding to mast cells
histamine
causes small blood vessels to become dilated which causes hives
runny nose, watery eyes, itching
asthma
when allergen is inhaled symptoms appead because SMM in walls of bronchioles contracts –> constricting passages and restricting air flow
anaphylatic shock
fairly rare body wide or systemic acute allergic response
occurs when allergen directly enters blood and circulates rapidly through body
since entire body is involved, it is life threatening
causes and effects of anaphylactic shock
certain bee stings, spider bites, injection of haptens
difficulty breathing when SMM of lungs contract, lung passages contract, sudden vasodilation + fluid loss, circulatory collapse, death within mins
epinephrine
drug of choice to reverse histamine mediated effects
delayed hypersensitivity
not histamine mediated
rather reaction mediator is lymphokines from activated T cells
1-3 days after contact, corticosteroid drugs are used for relief
allergic contact dermatitis
skin contact w/ poison ivy,, heavy metals like lead/mercury, cosmetic + deodorant chemicals that act as haptens and are diffused through skin
mantoux, tine, skin tests for TB detection
depend on delayed hypersensitivity reaction
when antigens are injected just under skin, small hard lesion forms if person has been sensitized
immunodeficiencies
can be congenital or acquired
production or function of immune cells or complement is abnormal
severe combined immunodeficiency disease SCID
most severe congenital
deficit of B + T cells
bc T cells are necesasry for normal operation of both arms of immune response, afflicted children have no protection against any pathogens
minor infections are letal
bone marrow transplants or umbilical cord blood (have normal lymphocyte stem cells) can help but patients have to live in a protected environment
acquired immune deficiency syndrome AIDS
most severe acquired
cripples immune system by interfering in activity of helper T cells
autoimmune disease
when immune system loses ability to tolerate self antigens and attack foreign antibodies
body produces autoantibodies and sensitized T cells that attack and damage its own tissues
multiple sclerosis AID
white matter (myelin sheaths) of brain and spinal cord are destroyed
myasthenia gravis AID
impairs communication between nerves and SKM
graves disease AID
thyroid gland produces excessive amounts of thyroxine
juvenile diabetes AID
destroys pancreatic beta cells that produce insulin
rheumatoid arthritis AID
destroys joints
cause of autoimmune disease or self-tolerance breakdown
3 reasons that trigger normal state of self-tolerance to break down
- inefficient lymphocyte programming
instead of being destroyed, self reactive B and T lymphocytes just move somewhere else
- appearance of self-proteins in circulation that have not been exposed to immune system
hidden antigens are found in eggs, sperm, eye lens, certian proteins in thyroid gland
new self antigens may appear as a result of gene mutations or alteration in self-proteins by hapten attachment or by bacteria/viral damage
- cross reaction of antibodies produced against foreign antigens with self-antigens
ex. antibodies produced during an infection caused by streptococcus bacteria can cross react with heart antigens and cause damage to heart muscle, valves,joints, kidneys
known as rheumatic fever
developmental aspects of lymphatic system + body defenses
lymphoid organs are poorly developed before birth except for thymus + spleen
newborn only has passive immunity from mother, no functioning lymphocytes
if lymphatics are removed or lost, severe edema, but vessels grow back in time
