Alterations in immune response Flashcards
what are the two arms of adaptive (acquired) immunity
1) humoral (B cells)
2) cellular (t vells)
what do humoral cells do?
produce antibodies for bacteria and viruses
what do cellular (t cells) do?
react directly with antigen (protein) on cell surface
- deal with viruses and cancer cells
what is hypersensitivity?
Excessive or inappropriate immune response to an antigen that results in disease or damaged to the host
- includes allergy, autoimmunity, and alloimmunity
- may be either antibody mediated (b cells) or cell mediated (t cells)
what is an allergy?
Harmful effects of hypersensitivity to environmental (exogenous) antigens
what is the def of autoimmunity?
Disturbance in the immunologic tolerance of self-antigens
- breakdown of self-tolerance
- body recognizes self-antigens as foreign
- cause isnt understood
what is the def of alloimmunity?
Immune reactions to tissues of another individual (transplant, graft rejection)
what is most likely to cause a type 1 allergy?
-Against environmental antigens (allergens)
which antibody does a type 1 allergy rely on?
IgE
what is an antigen that causes an allergic reaction called?
allergen
what happens after IgE has attached to the mast cell?
It is sensitized, when a second exposure happens, the antigen binds to the mast cell and cause it to degranulate, releasing no inflammatory mediators (histamine)
what does histamine do in an allergic reaction?
It binds to HI, and causes smooth muscles around bronchi to contract = airways get smaller =difficult to breathe, causing blood vessels to dialte. Allergen is more easily able to squeeze through blood vessels, causing edema, and can lead to hives
which systems are most affected by a type 1 allergy?
skin, respiratory, and GI tract
what are some manifestations of a type 1 allergy?
itching urticaria (hives) conjunctivitis (inflammation of conjunctiva (eye) rhinitis (inflammation of nose) edema GI cramps and malabsorption
what can happen in a type 1 allergy?
anaphylactic reaction (life threathening allergic reaction)
can people be genetically predisposed to an anaphylactic reaction?
yes (atopic)
what occurs inside the body during an anaphylactic reaction?
wheezing difficulty breathing increased heart rate hypotension (decreased bp) nausea, vomiting, diarrhea possible respiratory arrest or failure
what can be used to treat anaphylactic reaction?
first line: epinephrine (main tx)
other; corticosteriod, anithistatime
what does a type 2 hypersensitivity reaction rely on
IgG and IgM (produced by B cells)
is a type 2 allergy tissue-specific or cell-specific
tissue specific
how does a type 2 allergy happen?
When some self-reactive immune cells escape their primary lympoid organs (thymus for T cells, Bone marrow for B cells)
These self reactive cells cacn then attack healthy tissue
what do self reactive B cells produce?
IgM and IgG
how does a type 2 allergy cause damage to cells?
the making of a antibody-antigen complex initiates the compliment system which attracts neutrophils, which dump enzymes that are highly cytotoxic to the cell = tissue damage
what are some examples of a type 2 allergy?
thrombocytopenia
transfusion reactions
hemoltic disease of the newborn
how does hemolytic disease of the newborn occur?
it occurs with a mom who is Rh- (tied to RBC’s) and baby is Rh+
during the delivery of the first baby, mother is exposed to RH factor and forms anitbodies
any pregnancy after the first, antibodies (IgG and IgM) in the mother will cause hemolysis in the fetus (causes breakdown of RBC’s in the baby)
how does hemolytic disease harm a newborn?
Mild- jaundice
severe- miscarriage
how can hemolytic disease of the newborn be prevented?
- prevent formation of antibodies by injection of Rh immune globulin duirng pregancy and after delivery
- identification of at risk babies (fetal Rh testing)
- exchange transfusion after baby born
whats the difference between type 2 hypersensitivity and type 3 hypersensitivity?
same antibodies, different process
where are antigen-antibody complexes formed in a hypersenitivity 2 and where are they later deposisted?
Formed in circulation and are later deposited in vessel walls or extravascular tissues, causing inflammation and tissue damage
what is an example of type 3 autoimmunity?
systemic lupus erthematosus
is systemic lupus erythematosus an example of an autoimmune disease and is it more common in females or males?
yes, and is more common in females for an unknown reason
what causes SLE?
IgG antibodies are specific to nucleoproteins ( on DNA), and this makes it self reactive
- in lupus, a DNA autoantigen might get released from a damaged cell, a self reactive B cell may bind to it, If a t cell that is also self reactive binds as well, it will activate the B cell and allow it to differentiate to a IgG secreting machine, making a much of IgH autoantigen complexes.
- these auotangiten complex arent as immunegenic, so they dont get removed from blood stream as fast.
- These complexes go into blood vessels, and cause edema, attracts neutrophils that the degradulate and cause tissue damage and necrosis, which causes swelling of blood vessels. this causes further cell damage, are more autoantigen complexes are released, repeating the cycle.
what are some clinical manifestations of SLE?
Arthralgias (joint pain) and arthritis vasculitis (swollen blood vessels) and rash renal disease hematologic changes cardiovasular disease
Does a type 4 hypersensitivity reaction involve b cells or antigen-antibody complexes?
no
Does a type 4 hypersensitivity reaction involve t cells?
yes
what can cause a type 4 reaction?
contact dermatitis, skin test for tb, posion ivy, acute organ rejection (organ transplant)
how to prevent organ rejection?
tissue typing (human leukocyte antigen (HLA matching) -immunosuppressive techniques, such as using corticosteroids, cytotoxic drugs, or anti-lymphocyte serum
what is an immune deficiency?
failure of immune mechanisms of self- defense
what are the two types of immune deficiency?
primary (congenital) immunodeficiency (born with it)
Secondary (acquired) immunodeficiency (acquired through aging process)
what are immune deficiencies mediated by?
B cells, T cells, or both
what is the clinical hallmark for immune deficiencies?
the development of unsual or recurrent, severe infections
Characteristics of a B cell deficiency? (humoral)
recurrent and life-threatening bacterial infections
characteristics of T cell deficiency? (cellular)
can be viral, fungal, yeast, and atypical microorganism
-susceptible to weird infections and cancers because t cells fight cancer
what’s worse, a B cell deficiency or a T cell deficiency?
Since T cells stimulate B cells, having a T cell deficiency would be worse because that would mean you would have both a T cell and B cell deficiency.
whats an example of a T cell deficiency?
DiGeorge syndrome (primary -born with it)
what is DiGeorge syndrome?
A collection of findings:
- Partial lack of thymus
- Cardiac and aortic defects
- abnormal facial features
- Thymic aplasia/ Hypoplasia ( under development)
- Cleft palate
- hypocalcemia / hypoparathyrodism
whats more common, primary deficiencies or secondary?
secondary
what is an example of a secondary immune deficiency?
AIDS (aquired immnuodeficiency syndrome)
what does HIV do to the body?
depletes the body’s CD4 T helper cells ( these cells are needed for development of both plasma cells (antibodies) and cytotoxic T cells )
how is HIV spread?
bloodborne pathogen transmitted through sexual contact, blood to blood contact, and through placenta, contact with blood at birth, or through breastfeeding
are incidences higher in women or in men?
in women ;(
What is included in the first stage of infection of HIV?
acute infection:
- Within the first 2-4 weeks of infection
- flu like symtoms
- antibodies usually appear 4-7 weeks of exposure
what is the second phase of HIV?
clinical latency
- lasts for years
- asymptomatic
- with treatment, may last several decades
What is the last stage of HIV?
AIDS
-vulnerable to infections and cancer
what has to be present for diagnosis of HIV?
- presence of virus
- decrease CD4 T helper cells
what has to be present for diagnosis of AIDS?
Opportunistic infections and cancer
CD4 T helper cellls less than 200 cells /mm3
what weird manifestations can be present with aids?
kaposi sarcoma
vision issues
what are some treatments for immunodeficiencies
(replace missing component of the immune system)
-gamma globin therapy
-transplantation (bone marrow, thymus transplatation (DiGeorge), stem cell)
Gene therapy
