Class 2 Flashcards
In order for T-cells to recognize and respond to an antigen, it must be presented by ________________________________.
another cell or an antibody.
For T-cells to recognize & respond to an antigen, it must be presented by another cell or antibody. It must be coded by Major Histocompatibility Complex (MHC) = ___________________________________________________. In humans, they are often called ____________________________.
• a group of genes on chromosome 6 that determine tissue & blood compatibility.
• Human Leukocyte Antigens (HLA).
What are the 2 classes of HLA?
-Class I are on all cell surfaces
-Class II are on immune system cells
HLA are key factors in determining self from non-self. However, they can also identify self-targets as well as…
-They lead to T-cells attacking, or ignoring an antigen
-They are genetically determined self-markers
T-cells will attack or ignore an antigen based on the ______.
Human Leukocyte Antigens (HLA)
Immunity is acquired in four ways and can be active or passive. What is the difference between active and passive immunity?
• active = body develops its own antibodies (B-cells run into antigens & start pumping out antigens)
• passive = body is given antibodies
What is the 4 ways immunity is acquired?
1) Active natural immunity – develops through direct exposure to antigen
2) Active artificial immunity – develops when body is purposefully introduced to antigen (ex. vaccines)
3) Passive immunity – passed from mother to fetus
4) Passive artificial immunity – injected from one system to another
What is Immunologic self-tolerance?
Ability to distinguish between self & non-self antigens.
In a healthy individual, mechanisms are put in place to eliminate T or B-cells that fail to differentiate between two antigens. What happens when these mechanisms fail?
When these mechanisms fail, autoimmune disorders arise.
What is Auto-immunity?
Mounting of an immune response against body’s own tissues.
Auto-immunity is the mounting of an immune response against the body’s own tissues. What are the reasons this happens?
➢ Attacked body tissue may have similar characteristics to a microbe the immune system has just battled.
➢ Some HLA inheritance corresponds to activation of autoimmune disease.
➢ Sometimes there is an over response of immune activities.
➢ Sometimes there is a reduced T-cell suppressor response.
In Rheumatoid Arthritis (RA), there is an autoimmune response to self-IgG. The resulting body is called ____________________.
Rheumatoid factor
What is rheumatoid arthritis?
• RA involves immune system attack on synovial membranes of joints, eventually leading to bone erosion & joint deformities.
- Tender, warm, painful joints; joint stiffness following inactivity
What is multiple sclerosis?
- Auto-antibodies create an immune attack on self-myelin in CNS’s neurons (specifically the neuroglial cell: Oligodendrocytes).
- Depending on what region of brain is affected, there will be varying outcomes.
In Multiple Sclerosis (MS), auto-antibodies create an immune attack on self-myelin in the CNS’s neurons (specifically the neuroglial cell: ___________________).
Oligodendrocytes
What is an autoimmune disease where acetylcholine receptors at neuromuscular junction are destroyed by immune cells after having been bonded by auto antibodies.
Myasthenia Gravis
T/F Auto antibodies bind with self molecules to create immune complexes
True
T/F In RA and SLE, such immune complexes travel in bloodstream to target tissues like joints. By gathering in these tissues, immune complexes subject them to intense tissue destruction from immune system responses & their sequelae.
True
T/F There may be mistaken targeting of self cells as dangerous
*True
Since some self cells (ex. virus infected cells, or cancerous cells) are identified & presented for destruction, misidentification is possible. This has been found to occur in reactions to drugs and viruses that appear to have altered cellular markers in affected person’s body.
T/F Auto-immunity can have elements of hypersensitivity reactions
*True
Immune complexes attract inflammatory & cytotoxic reactions where tissue damage is result of intense responses related to complement activation & killer cell activity. This component of diseases like RA & SLE is type III hypersensitivity reaction. Response is more destructive than stimulus warrants. In examples stimulus is an autoimmune one.
T/F Autoimmune diseases are more common in women than men?
Autoimmune diseases are more common in women then men, not quite understood why but possible that it’s a hormonal component.
Treatment tends to involve use of corticosteroids & immunosuppressive drugs to try to counter or reduce _______________________________.
cellular damage being caused by immune system response.
What are hypersensitivity disorders?
Refer to excessive or inappropriate activation of immune system to exogenous (=outside the body) & endogenous (=inside the body) antigens that produce inflammation & cause tissue damage.
What are the 4 categories of hypersensitivity responses?
(*Remember: ABCD)
* TYPE I – IMMEDIATE HYPERSENSITIVITY
* TYPE II – ANTIBODY MEDIATED HYPERSENSITIVITY aka CYTOTOXIC HYPERSENSITIVITY
* TYPE III – IMMUNE COMPLEX MEDIATED HYPERSENSITIVITY
* TYPE IV – DELAYED OR CELL-MEDIATED HYPERSENSITIVITY
Key features of type 1-Immediate Hypersensitivity
• Mediated by IgE, leads to release of inflammatory mediators from sensitized mast cells.
• Reaction takes place with second & subsequent exposures to antigen, not with initial exposure.
• Response begins rapidly, often within minutes of antigen challenge.
-Referred to as Allergic Reactions, antigen in this case would be referred to as an allergen.
Type 1 responses vary in severity. What are the different types?
• Mild, but annoying (ex. seasonal allergies)
• Severely debilitating (ex. asthma)
• Life threatening (ex. anaphylaxis)
Type 1 responses can vary based upon site of involvement. What are these called?
• Local (atopic) reactions
• Systemic reactions (anaphylaxis)
What are examples of Local/Atopic Reactions?
- Allergic Rhinitis
- Asthma
- Urticaria (Hives)
- Angioedema (aka Quincke’s edema, Angioneurotic edema)
- Gastrointestinal food allergies
What is Allergic Rhinitis?
• Edema & hypersecretion of mucosal lining of nasopharyngeal cavities by allergens like pollen.
• May be aggravated by high humidity, irritating vapours, & upper respiratory tract infections.
• Lasts for days to weeks.
• Can lead to complications like sinusitis or nasal polyps
What is Asthma?
Lung disorder characterized by bronchoconstriction, edema, & increased secretion of thick mucus in bronchi -> constriction of airways.
What is Urticaria (Hives)?
• Local wheals & erythema in upper dermis
• Associated with PRURITIS (itchiness)
• Develops rapidly after exposure to allergen
• Allergens can be ingested (eg. food, medication) or introduced through skin (ex. bee stings)
What is Angioedema (aka Quincke’s edema, Angioneurotic edema)?
• Generalized edema of skin, lips, face, tongue, pharynx, &/or mucosa
• Allergens similar to urticaria
• Similar to hives, but swelling takes place deeper in dermis
What are Gastrointestinal food allergies?
• Allergic reaction in GI tract begins shortly after food ingestion
• Symptoms are primarily seen in GI tract, skin, and respiratory system (ex. nausea, vomiting, abdominal cramps, diarrhea, hives, asthma); anaphylaxis
• A common allergen is shellfish
What is an example of Systemic/ Anaphylactic Reactions?
Anaphylaxis
What is Anaphylaxis?
• Systemic life-threatening hypersensitivity reaction. Acute generalized reaction characterized by itching, generalized flushing, headache, difficulty breathing, & drop in blood pressure which can lead to shock & loss of consciousness.
• Caused by smooth muscle contraction & vascular
dilation as reaction to released mediators.
• Common allergens are food, chemicals, insect stings, &
drugs. Treatment is subcutaneous administration of
epinephrine.
What is TYPE II - ANTIBODY MEDIATED HYPERSENSITIVITY AKA CYTOTOXIC HYPERSENSITIVITY?
• Mediated by IgM or IgG
• Response is directed against target antigens on cell
surfaces or in extracellular tissue.
• Reactions commonly involve formation of antibodies
directed against blood cells & their destruction.
What is Hemolysis
rupture or destruction of RBCs
What is Rhesus (RH)?
blood group system. refers to wether your blood
has RH factor.
What is RH Factor?
a protein on RBC
What are Erythrocytes?
HgB, gives the red colour to blood, transports O2, CO2 to & from tissues
What is Erythroblastosis Fetalis?
• A hemolytic disease, affects neonates -> hemolytic
anemia/ erythroblastosis neonatorum in neonates
• Occurs if mother is Rh- & fetus is Rh+ in subsequent
pregnancies.
• Rh+ antibodies formed in mother’s system from her first Rh+ pregnancy, cause hemolysis of red blood cells during second pregnancy -> anemia, jaundice, & edema of child
What is Autoimmune Hemolytic Anemia?
• Antibodies produced by patient’s own body are responsible for hemolysis of erythrocytes
• Is manifested as anemia
• Treatment includes use of corticosteroids &/or
splenectomy
What are Blood Transfusion Reactions?
• Triggered when an incompatible blood type is
administered
• Manifests as fever, chills, & renal failure due to hemolysis of red blood cells
• Can be prevented by checking blood groups & doing cross-matching before blood transfusion
What is Autoimmune Thrombocytopenia (AITP)?
• Body produces antibodies that are directed against platelets
• Response manifests as PETECHIAE (small hemorrhages),
purpura (bruising) & mucosal bleeding (nose, stomach, vagina)
• Treatment includes use of corticosteroids &/or splenectomy
What is TYPE III - IMMUNE COMPLEX MEDIATED HYPERSENSITIVITY?
• Mediated by formation of antigen-immunoglobulin complexes, complement fixation, & localized inflammation
• Involves IgM and IgG antibodies. Immune complexes formed in body’s circulatory system are deposited in different areas of body (ie. Blood vessels, joint spaces)
• Subsequent immune response causes inflammation &
tissue destruction of surrounding structures.
What is Arthus Reaction – local response?
• performed for experimental purposes & involves injection of foreign substance.
• usually results in complex formation & localized skin reactions (edema, hemorrhage, necrosis)
What is Serum Sickness – systemic response?
• Caused by animal serum or drugs (ex. penicillin)
• Antibodies are developed to serum or drug antigen, which results in formation of antigen-antibody complex
• Complexes get lodged in small vessels & cause
inflammatory reaction (acute vasculitis)
• Symptoms include fever, painful joints, enlarged lymph nodes & spleen, & urticaria
What is Glomerulonephritis – local effects?
• Acute streptococcal infection is responsible for formation of antibodies
• Streptococcus antigen & antibodies form immune complex
• Complex is deposited on glomerular basement membrane, leading to inflammation of glomerulus
• Symptoms include HEMATURIA & PROTEINURIA
What is Polyarteritis Nodosa – systemic effects?
• Disease is characterized by inflammation & necrosis of medium-sized arteries with secondary ischemia of tissues supplied by affected blood vessels
• Inflammation is caused by immune complex formation
• Antigen can be penicillin or hepatitis B virus
• Can lead to fatal complications such as occlusion or rupture of blood vessels
What is TYPE IV - DELAYED OR CELL-MEDIATED HYPERSENSITIVITY?
-Mediated by specifically sensitized T-lymphocytes
-Response manifests as sub-acute or chronic inflammation
with infiltration of tissue by lymphocytes & macrophages, resulting in variable degrees of necrosis.
Type I, II, III are ________________________ and _________________; Type IV is _____________________ and ________________.
• antibody-mediated
• immediate
• cell-mediated
• delayed
What is Contact Dermatitis?
• Acute or chronic delayed type of hypersensitive response to allergens placed on skin surface
• Caused by plants (eg. poison ivy, poison oak), drugs, cosmetics, dyes, paints, & jewelry
• Symptoms usually occur 12-24 hours after exposure & can last from a few days to weeks
• Manifests as skin erythema, edema, pruritis, vascular eruption, necrosis
What is Graft Rejection?
• Caused by a delayed hypersensitivity reaction
• Development of chronic inflammation because of infiltration of graft by lymphocytes & macrophages. Leads to necrosis of graft.
T/F Latex allergies can be Type I and/or Type IV?
True
Type I latex reactions are ________________ and often ____________________.
• immediate
• life-threatening
Type IV latex reactions are ___________________ and tend to manifest as ________________________.
• more common
• contact dermatitis
