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step1 Immun FC-RX
Immunology- didnt know
| Question | Answer |
|---|---|
| The hinge region of an antibody connects which 2 domains? | The Fab region of the heavy chain and the Fc region; specifically, CH1 and CH2 domains |
| What are the 4 domains that comprise the Fab region of an antibody? | Variable light region (VL), constant light region (CL), variable heavy region (VH), constant heavy 1 region (CH1) |
| Which antibody isotype acts as the main antibody in the secondary, delayed response to an antigen? | IgG |
| List 4 main functions of IgG. | 1. Fixation of complement, 2. opsonization of bacteria, 3. neutralization of bacterial toxins and viruses, 4. provision of passive immunity to infants via placenta |
| Which cell surface proteins are found on macrophages? | CD14, CD40, CCR5, MHC II, B7 (CD80/86), and receptors for Fc and C3b |
| IgA crosses epithelial cells by transcytosis. In which structural form is IgA secreted? | Dimeric form, with J chain (monomeric form only found in serum) |
| Unlike other immunoglobulin (Ig) isotypes, the function of IgD is unclear. Where can immunoglobulin D be found? | Surface of many B cells and in serum |
| To what specific region(s) of the heavy chain do macrophages bind? | CH2 and CH3 regions |
| Which molecular cofactor is required for both the creation and neutralization of reactive oxygen species (ROS)? | NADPH |
| Which type of influenza vaccine is theoretically safer for most patients to receive? | The injected influenza vaccine, which is killed/inactivated (unlike the intranasal influenza vaccine, which is live attenuated) |
| What 3 symptoms are seen in patients with Wiskott-Aldrich syndrome? | Wiskott-Aldrich: Thrombocytopenia, Eczema, Recurrent (pyogenic) infections (WATER) |
| DiGeorge syndrome, IL-12 receptor deficiency, Job syndrome, and chronic mucocutaneous candidiasis feature dysfunction of which cell type? | T cells |
| What is the pathophysiology of leukocyte adhesion deficiency type 1? | Lack of LFA-1 integrin (CD18) on phagocytes → impaired migration and chemotaxis |
| Anti-U1 RNP (ribonucleoprotein) autoantibodies are associated with which disorder? | Mixed connective tissue disease |
| A patient with leukemia receives a bone marrow transplant and develops graft-versus-host disease. How is this a potentially desirable effect? | This may be beneficial in the eradication of leukemia cells (the "graft-versus-tumor" effect) |
| A 6-year-old girl with nausea, vomiting, polyuria, and sudden weight loss has a blood glucose level of 800 mg/dL. Lab tests for which autoantibodies should be ordered? | Anti-glutamic acid decarboxylase and islet cell cytoplasmic autoantibodies (to check for type 1 diabetes) |
| Which type of vaccine stimulates the immune system to make antibodies without potential for causing disease? | Toxoids |
| Bruton agammaglobulinemia, selective IgA deficiency, and common variable immunodeficiency are disorders of which type of leukocyte? | B cells |
| What general type of vaccine includes only the antigens that best elicit an immune response? | Subunit vaccines |
| Which immunodeficiency results in low T-cell counts, ↓PTH, and ↓Ca2+? | Thymic aplasia=both erd and 4thPP (which can lead to tetany secondary to parathyroid aplasia, recurrent viral/fungal infection due to ↓T cells). note pth thymus and inferior parathyroid derived from third pharyngeal pouch(PP), superior paratyroid from 4 |
| Which immunodeficiency syndrome is the most common cause of Mendelian susceptibility to mycobacterial diseases (MSMD)? | IL-12 receptor deficiency |
| Rheumatoid factor, often positive in rheumatoid arthritis, is an autoantibody targeting which immunoglobulin? | It is an IgM antibody against the Fc region of IgG |
| What can be observed on flow cytometry and lymph node biopsy from a patient with severe combined immunodeficiency? | Lack of T cells on flow cytometry and no germinal centers in lymph nodes |
| A patient presents with swelling and pain in her PIP and MCP joints, bilaterally. Of the autoantibodies associated with this condition, which are more specific? | Anti-CCP autoantibodies (this is rheumatoid arthritis) |
| MPO-ANCA/p-ANCA autoantibodies are associated with which 3 disorders? | Microscopic polyangiitis, Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis), and ulcerative colitis |
| What gene mutation leads to autosomal dominant hyper-IgE syndrome (Job syndrome)? | STAT3 mutation, which leads to Th17 deficiency, resulting in impaired neutrophil recruitment to infection sites |
| What does a live attenuated vaccine contain? | A microorganism that has been modified to lose its pathogenicity (though it retains the capacity for transient growth within the host) |
| A 4-year-old girl is diagnosed with common variable immunodeficiency. What type of poliovirus vaccine may be contraindicated? | The Sabin oral vaccine (live, attenuated polio vaccines are contraindicated for patients with B-cell deficiencies) |
| hich 2 types of hypersensitivity reactions are implicated in the development of chronic transplant rejection? | Type II and IV hypersensivity (involving both humoral and cellular components) |
| A kidney transplant recipient experiences gradual oliguria. Biopsy reveals vasculitis of graft vessels with a lymphocytic cellular infiltrate. What type of rejection is present? | Acute rejection |
| What is the pathogenesis of chronic granulomatous disease? | Defective NADPH oxidase → ↓ ROS and oxidative burst → ↑ susceptibility to catalase ⊕ organisms |
| Myasthenia gravis, Graves disease, and pemphigus vulgaris are examples of what type II hypersensitivity mechanism? | Cellular dysfunction, in which the opsonized cells do not function normally but are not completely destroyed |
| After a camping trip, a patient presents with an itchy, red, oozing rash on the lower extremities, sparing the soles of his feet. What is the diagnosis? | Contact dermatitis, likely caused by poison ivy (a type IV hypersensitivity reaction) linear pattern |
| What test is used to determine T-cell immune function, via a type IV hypersensitivity-mediated reaction? | Candida skin test |
| What are 10 key examples of live vaccines? | Adenovirus/Typhoid/Polio/Varicella/ Smallpox/BCG/Yellow fever/Influenza/ MMR/Rotavirus (Attention Teachers! Please Vaccinate Small, Beautiful Young Infants with MMR Regularly) |
| A man comes to the clinic with a disseminated mycobacterial infection after receiving the BCG vaccine. He has low IFN-γ levels. Which leukocytes are affected in this patient? | Th1 cells (he has IL-12 receptor deficiency) |
| What cardiac defects are typically associated with DiGeorge syndrome? | Conotruncal abnormalities, such as tetralogy of Fallot and truncus arterious |
| What conditions might be seen in patients with common variable immunodeficiency? | Autoimmune diseases, bronchiectasis, lymphoma, sinopulmonary infections |
| What is the classic triad of presentation seen in ataxia telangiectasia? | Ataxia, spider Angiomas, decreased IgA |
| What is the general difference between infections commonly associated with T-cell and B-cell deficiencies? | T-cell deficiencies tend to produce recurrent viral/fungal infections, while B-cell deficiencies tend to produce recurrent bacterial infections |
| What is a specific pathologic manifestation of chronic rejection in a transplanted lung? | Bronchiolitis obliterans |
| What are the characteristic lab findings in Wiskott-Aldrich syndrome? | Normal/decreased IgG and IgM, elevated IgE and IgA, thrombocytopenia with microsized platelets |
| A patient has a history of several miscarriages and venous thromboses. Labs show prolonged PTT. What autoantibodies are associated with this syndrome? | Anti-β2 glycoprotein I, lupus anticoagulant, and anticardiolipin autoantibodies (she has antiphospholipid syndrome) |
| A young child has no B cells in peripheral blood, low immunoglobulins, and scanty tonsils. What is the diagnosis? | X-linked (Bruton) agammaglobulinemia |
| Name the 2 primary autoantibodies associated with Hashimoto thyroiditis. | Antithyroglobulin and antithyroid peroxidase (antimicrosomal) autoantibodies |
| Patients with ataxia-telangiectasia are at increased risk for which malignancies? | Lymphomas and leukemias |
| A child has a fever, headache, flushing, and chills 4 hr after receiving a blood transfusion. How could this be prevented in the future? | By using leukoreduced blood (in which WBCs have been removed); this is febrile nonhemolytic reaction (mediated by cytokines released from accumulated donor WBCs) |
| How is a killed vaccine prepared? | The pathogen is inactivated with heat or chemicals before administration (leaving the epitope structure on surface antigens intact) |
| A new mother expresses concern that her baby will have a "bad reaction" to the Hib (Haemophilus influenzae type b) vaccine. What is the correct response? | The chance of an adverse reaction to a subunit vaccine (eg, Hib) is extremely low, even relative to other vaccine types |
| A child has recurrent bacterial skin infections with absence of pus and impaired wound healing. What lab findings might confirm the diagnosis? | Increased serum neutrophil levels but lack of neutrophils at infection sites (this is type 1 leukocyte adhesion deficiency) |
| Name the autoantibodies associated with dermatomyositis and polymyositis. | Antisynthetase (eg, anti-Jo-1), anti-SRP, and anti-helicase (anti-Mi-2) |
| A woman has ataxia, weblike angiomas, low IgA levels, high AFP, and cerebellar atrophy on imaging. Which gene is defective? | The ATM gene: ataxia-telangiectasia is due to ATM gene defects encoding DNA repair enzymes |
| A mother is Rh- and her fetus may be Rh+. Which Coombs test should each of them receive? | Test mother blood for Rh+ antibodies with indirect Coombs test; test fetal blood for antibodies adhered to RBCs with direct Coombs test |
| A patient with HIV infection has a CD4 count of 600 cells/mm3. What are the 2 live attenuated vaccines that can be given to this patient? | MMR and varicella vaccines can be given to HIV+ patients with a CD4 cell count ≥ 200 cells/mm3 |
| A patient with pancytopenia who is undergoing marrow chemoablation in preparation for bone marrow transplantation requires blood products. What must be done before transfusion? | The blood products must be irradiated (as this helps prevent GVHD in immunocompromised patients) |
| What are 6 key examples of subunit vaccines? | HBV (antigen is HBsAg), HPV (types 6, 11, 16, 18), acellular pertussis (aP), Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b |
| What is the pathogenesis of Wiskott-Aldrich syndrome? | Mutation in WAS gene leads to inability of leukocytes and platelets to reorganize actin cytoskeleton, resulting in defective antigen presentation |
| What is serum sickness? | An immune complex disease; antibodies to foreign proteins are made and deposited in tissues, where they fix complement and cause damage |
| What effect can a T-cell deficiency have on a bacterial infection? | Increased risk of sepsis (due to rapid dissemination of the infection) |
| What are the modes of inheritance of leukocyte adhesion deficiency (type 1) and Chédiak-Higashi syndrome? | Both have an autosomal recessive inheritance pattern |
| A patient receiving induction chemotherapy for acute leukemia has severe granulocytopenia. To what types of microbes is she most susceptible? | Bacteria (Some Bacteria Produce No Serious granules: Staphylococcus, Burkholderia, Pseudomonas, Nocardia, Serratia) and fungi (systemic Candida, Aspergillus, Mucor) |
| A patient with fevers and a new heart murmur is found to have tricuspid endocarditis. Blood cultures grow yeasts with pseudohyphae. What immune cell count may be reduced? | Granulocytes may be deficient (increasing the risk of systemic or bloodstream candidal infections) |
| Which condition caused by T-cell dysfunction presents with persistent noninvasive Candida infection? | Chronic mucocutaneous candidiasis |
| An hour after blood transfusion, a patient has a fever, dyspnea, flank pain, and jaundice. Which type of hypersensitivity reaction is this? | Type II hypersensitivity reaction, an acute hemolytic transfusion reaction mediated by antibodies to donor RBC surface antigens, with extravascular hemolysis (jaundice) |
| An hour after blood transfusion, a patient has a fever, dyspnea, flank pain, and jaundice. Which type of hypersensitivity reaction is this? | Type II hypersensitivity reaction, an acute hemolytic transfusion reaction mediated by antibodies to donor RBC surface antigens, with extravascular hemolysis (jaundice) |
| List the symptoms of hyper-IgE (Job) syndrome using the mnemonic ABCDEF | Noninflamed staphylococcal Abscesses, retained Baby teeth, Coarse facies, Dermatologic problems (eczema), high IgE, Fractures from minor trauma (Learn the ABCDEF’s to get a Job!) |
| A patient with IgA deficiency develops wheezing, hypotension, and respiratory arrest after receiving a blood transfusion. What is the most likely cause? | Type I hypersensitivity reaction to plasma proteins in donor blood; patients with IgA deficiency must receive blood products that do not contain IgA |
| What autoantibodies are associated with diffuse scleroderma? | Anti-Scl-70 (anti-DNA topoisomerase I [Scleroderma]) |
| What is the pathogenetic mechanism whereby hyperacute rejection develops? | Pre-existing recipient antibodies react to donor antigens (type II hypersensitivity), causing thrombosis of graft vessels and necrosis |
| What is a common histologic manifestation of chronic rejection of a liver transplant? | Vanishing bile duct syndrome |
| Which immunodeficiency can cause a false-positive β-hCG test result? | Selective IgA deficiency (most common primary immunodeficiency; unknown cause) |
| A young patient is found to have an absence of B cells. To which types of viruses is he most susceptible? | Enteroviruses, including poliovirus (especially manifesting as enteroviral encephalitis) |
| The umbilical cord fails to separate within 30 days in a neonate. Neutrophilia is noted on labs. What is the diagnosis? | Leukocyte adhesion deficiency type 1 |
| What is the main drawback associated with toxoid vaccines? | They stimulate the production of antitoxin levels that decrease with time (requiring subsequent boosters) |
| Which 4 types of HPV does the standard quadrivalent subunit HPV vaccine protect against? | Types 6, 11, 16, and 18 |
| A patient develops hives, fever, and shock within minutes of receiving a blood transfusion. What is the pathogenesis behind this transfusion reaction? | Type I hypersensitivity reaction against plasma proteins in the transfused blood (this is an allergic/anaphylactic reaction) |
| What are the common causes of serum sickness-like reactions? | Drugs such as penicillin (acting as haptens) and infections such as hepatitis B |
| Which vaccine against Salmonella typhi poses a lower risk of causing infection? | The intramuscular Vi polysaccharide typhoid vaccine, which is killed/inactivated |
| What antibodies are associated with autoimmune hepatitis type 1? | Anti-smooth muscle autoantibodies |
| What 3 immunoglobulin isotypes are typically decreased in patients with ataxia-telangiectasia? | IgA, IgG, and IgE |
| What is the pathogenesis of a delayed hemolytic transfusion reaction? | An anamnestic response to a foreign antigen (usually non-ABO antigens previously encountered by the recipient) on the donor RBCs |
| What is the most common cause of hyper-IgM syndrome? | Defective CD40L on T-helper (Th) cells, which is necessary for B-cell class switching |
| When a cell is opsonized (coated) by antibodies in a type II hypersensitivity reaction, what are the cell's 2 potential fates? | Phagocytosis and/or complement system activation or destruction by natural killer cells (antibody-dependent cellular cytotoxicity) |
| A patient develops respiratory distress due to noncardiogenic pulmonary edema within 4 hours of receiving blood products. What is the cause? | Transfusion-related acute lung injury |
| Describe the mechanism of serum sickness. | Antibodies to foreign proteins are produced; 1–2 wk later, antibody-antigen complexes are formed and deposited in tissue → complement activation → inflammation/tissue damage |
| A 30-year-old woman has exophthalmos, palpitations, diarrhea, and thyromegaly. What autoantibodies cause this condition? | Anti–thyroid-stimulating hormone receptor autoantibodies (she has Graves disease) |
| Autoimmune hemolytic anemia, ITP, transfusion reaction, and hemolytic disease of the newborn are examples of which mechanism of type II hypersensitivity? | Cellular destruction in which cells are opsonized and then undergo either NK cell killing or phagocytosis and/or complement system activation |
| A previously healthy woman, not taking any medications, develops dry eyes and dry mouth. What autoantibodies can cause this? | Anti-Ro/SSA and anti-La/SSB autoantibodies, often positive in Sjögren syndrome |
| A 52-year-old man, diagnosed with small cell lung cancer, has muscle weakness that gets better throughout the day. Which autoantibodies are associated with this disorder? | Anti-presynaptic voltage-gated calcium channels; he has Lambert-Eaton myasthenic syndrome, a paraneoplastic syndrome associated with small cell lung cancer |
| A boy has coarse facies, retained baby teeth, and recurrent abscesses. Labs show ↑ IgE and ↑ eosinophils. Which immune cells are impaired? | Th17 cells (he has hyper-IgE syndrome [Job syndrome]) |
| Although most individuals with IgA deficiency have no symptoms, what symptoms can be present that allow for diagnosis? | Airway and GI infections, Autoimmune disease, Atopy, and Anaphylaxis to IgA-containing products |
| What pathogenetic mechanism drives the development of graft-versus-host disease? | Grafted immunocompetent T cells proliferate in the immunocompromised host and reject cells with foreign proteins, causing severe organ dysfunction |
| What live viral vaccine is nonattenuated and only given to military recruits? | Adenovirus |
| A patient develops worsening edema and necrosis at the site of recent tetanus vaccination. What is the diagnosis? | Arthus reaction: preformed antibodies attack injected antigen leading to formation of immune complexes in the skin and complement activation |
| Name the 3 autoantibodies associated with celiac disease. | IgA and IgG deamidated gliadin peptide, IgA anti-endomysial, IgA anti-tissue transglutaminase autoantibodies |
| A boy has thrombocytopenia, eczema, and recurrent pyogenic infections. This patient has an increased risk for what conditions? | Malignancy and autoimmune diseases (he has Wiskott-Aldrich syndrome) |
| What is the mechanism of injury in transfusion-related acute lung injury? | Sequestered neutrophils: 1) are primed in pulmonary vessels; 2) get activated in transfused blood and release inflammatory mediators → ↑capillary permeability → pulmonary edema |
| What is the pathogenetic mechanism whereby acute cellular rejection develops? | CD8+ T cells and/or CD4+ T cells are activated against foreign (donor) MHCs in a type IV hypersensitivity reaction |
| How rapidly does acute (cellular or humoral) transplant rejection develop? | Within weeks to months of transplantation |
| Name 4 inherited immunodeficiencies that are X-linked recessive and thus are more common in boys. | Hyper-IgM syndrome, Wiskott-Aldrich syndrome, chronic granulomatous disease, Bruton agammaglobulinemia (and some types of severe combined immunodeficiency) |
| Which disease is associated with anti-hemidesmosome autoantibodies? | Bullous pemphigoid |
| What are 5 key examples of inactivated or killed vaccines? | Hepatitis A, Typhoid (Vi polysaccharide, IM), Rabies, Influenza (injected), Polio (SalK = Killed) (A TRIP could Kill you) |
| A child with an inherited immune disorder has greasy, foul-smelling stools. What type of immunodeficiency is likely? | B-cell deficiency with no IgA (giardiasis), leading to lack of mucosal immunity |
| A patient experiences severe graft dysfunction within minutes of kidney transplantation. What is the correct treatment? | Removal of the graft (the appropriate treatment for a patient with hyperacute rejection, which occurs within minutes of transplantation) |
| Which disease is associated with antimitochondrial autoantibodies? | Primary biliary cholangitis |
| How does the humoral type of acute rejection differ from hyperacute rejection in its pathophysiology? | Antibodies against graft donor antigen(s) develop after transplantation in acute rejection (vs pre-existing antibodies in hyperacute rejection) |
| Describe the difference between a direct and an indirect Coombs test. | Direct: detects antibodies that are already bound to RBCs; indirect: detects free serum antibodies that can bind to RBCs |
| Which immunodeficiency is due to a defect in B-cell differentiation resulting in decreased plasma cell levels? | Common variable immunodeficiency (CVID) |
| Goodpasture syndrome, rheumatic fever, and hyperacute transplant rejection exemplify what type II hypersensitivity mechanism? | Inflammation, in which cell opsonization leads to complement system activation and Fc receptor–mediated inflammation |
| What is a specific pathologic manifestation of chronic rejection in a transplanted heart? | Accelerated atherosclerosis |
| What Ig isotype most commonly forms the immune complexes implicated in type III hypersensitivity reactions? | IgG |
| A patient has recurrent infections with encapsulated organisms, and B-cell counts are normal. What other immune disease may the patient have? | Early complement deficiency |
| What is the mechanism of the hypersensitivity reaction involved in polyarteritis nodosa? | In type III hypersensitivity, antigen-antibody complexes activate complement, leading to neutrophil chemotaxis and immune complex deposition |
| A pale, blond patient has recurrent pyogenic infections, lymphohistiocytosis, and neuropathy. Pancytopenia is noted. What cellular process is affected in this condition? | Defect in lysosomal trafficking regulator gene LYST leads to microtubule dysfunction, impairing phagosome-lysosome fusion (this is Chédiak-Higashi syndrome) |
| A patient agrees to receive the annual injected influenza vaccine. What is the main drawback of this type of vaccination? | Because it is an inactivated vaccine, the immune response is weaker (booster shots or repeated vaccinations are often required) |
| A patient has a rash on her cheeks, arthralgias, and antibodies to ANA and dsDNA. What type of hypersensitivity reaction causes this disease? | Type III (the patient has SLE) |
| Describe the mechanism of the late phase of a type I hypersensitivity reaction | fter mast cell degranulation, chemokines attract inflammatory cells and other mediators from mast cells, leading to inflammation and tissue damage |
| Describe the mechanism of a type III hypersensitivity reaction. | Anitigen-antibody complexes activate complement, attracting neutrophils that release lysosomal enzymes |
| A patient has thymic aplasia in the setting of DiGeorge syndrome. For what 5 types of viral infections is the patient at risk? | CMV, EBV, JCV, VZV, and chronic GI/respiratory viruses |
| What autoantibodies are associated with limited scleroderma/CREST syndrome? | Anticentromere antibodies |
| Name the gene affected in Bruton agammaglobulinemia. | BTK, which encodes for Bruton tyrosine kinase |
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