Immunology Flashcards
Second most common cause of severe combined immunodeficiency (SCID) and how does it cause the immunodeficiency?
Adenosine deaminase (ADA) [adenosine ⏩ inosine] deficiency ▶️ ⬆️ Adenosine ▶️ toxic to lymphocytes T and B
Which mechanism leads in a asplenic patient to have a severe bacterial infection? Immunologic functions of the spleen.
- 🚫 Systemic bacterial clearance ▶️ ⬆️ risk infections by encapsulated organism (vaccinate against S. pneumoniae, Hib, N. meningitidis)
- Blood filter ▶️ remove circulating pathogens; Major site of opsonizing antibody synthesis
What is the different between western blot and ELISA? And the similitude?
- Both identify proteins (Antibodies of the patient)
- ELISA ▶️ patient’s serum is tested directly (Ex look for Ab against some HIV proteins, or Ag as HBsAg)
- WB proteins are first separated by electrophoresis then the antibodies are added (in case to HIV test patient’s serum is added ▶️ Ex confirm that the Ab are specifically for the viral proteins directly extracted from the patient)
How is activated the classical complement pathway through C1?
C1 bind at least 2 different molecules of IgM or IgG ▶️ Fc portion near hinge region ▶️ C1 release catalytic factors for rest of pathway
How can you avoid the activation of classical complement pathway if no antigen is present?
Ag bind to IgM ▶️ expose region to bind C1; unbounded IgM hide C1 site binding ▶️ avoid activation without antigen.
Which enzyme is initially involved in ubiquitine proteasome pathway for the presentation of antigens in MHC type I? Function.
Ubiquitine ligase ▶️ recognize specific protein substrates and catalyze ubiquitine attachment
How do you identify a X-linked (Bruton) agammaglobulinemia and which is the gene mutated?
- Recurrent bacterial and enteroviral infections after 6 mo (⬇️ maternal IgG)
- Bruton tyrosine kinase gene (X-linked recessive) ▶️ maturation of B cells ▶️ stop until point to produce mu chain
- ⬇️Ig of all classes, ⬇️ peripheral CD19 cells, BM Bx ▶️ ⬆️ cells with cytoplasmic mu chains
What is the objective to administer anti-Rh(D) immunoglobulin to pregnant women? When is it applied?
- Anti-Rh(D) immunoglobulin (IgG anti-D, polyclonal Ab) ▶️ opsonize fetal RBC Rh (+) that enter to the maternal circulation ▶️ induce clearance by maternal reticuloendothelial macrophages (spleen) ▶️ avoid alloimmunization
- Give routinely all Rh (-) pregnancy at 28 weeks and immediately after birth
Recurrent skin and mucosal infections, without purulent secretion, absence of CD18 at leukocyte surface. Which other features do you find and what is the disease?
- Leukocyte adhesion deficiency→absence of CD18→no formation of functional beta-2 integrins
- Recurrent periodontal disease, persistent leukocytosis with neutrophilia, wound healing impaired and late separation of the umbilical cord (>21 days)
Classic triad of Reactive arthritis and with which genetic marker is associated?
- Nongonococcal urethritis (or enteritis) [1-4 weeks previously to next symptoms], conjunctivitis, oligoarthritis. 20% present sacroiliitis
- HLA-B27
*Seronegative spondyloarthropathy
Scenarios which graft vs host disease can develop. Background condition that allow the response and mechanism of disease.
- Bone marrow transplantation, transfusion of non-irradiated blood, organs rich in lymphocytes (as liver)
- Immunocompromised►primary disease or immunosuppressive medications→donor T cells from graft migrate into host tissues→recognize host MHC as foreigns→(+) CD4 and CD8 (no B cells)→host cell destruction
Most common organs affected by graft vs host disease.
- Skin→diffuse maculopapular rash with predilection by palms and soles (may desquamate)
- Liver→abnormal liver function tests (if transplant was liver, it could not be affected→recognized as self)
- GI tract→diarrhea, intestinal bleeding, abdominal pain.
In which background condition is the hyperacute rejection of a transplant developed?
Tissue recipient has antibodies against donor ABO antigens
*Minutes of transplantation→ischemia and necrosis
Substances resulting in degranulation of mast cells and basophils during anaphylaxis.
- Histamine
- Tryptase►specific of mast cells, ↑serum levels→support Dx of anaphylaxis (marker of mast cell activation)
How do you differentiate a cellular and humoral mediated acute transplant rejection reaction?
- Humoral→necrotizing vasculitis with a neutrophilic infiltrate, C4d deposition [Host B lymphocyte sensitization]
- Cellular→dense interstitial infiltrate of mononuclear cells (lymphocytes) and arterial intima (endothelitis) [Host T lymphocyte sensitization]
Treatment and prevention of acute transplant rejection reaction
- Prevent→calcineurin inhibitors (cyclosporine or tacrolimus)
- Tx→corticosteroids + maintenance calcineurin inhibitors
Surface marker for the monocyte-macrophage cell linage
CD14
Difference of type of immunity gotten by inactivated and live-attenuated influenza vaccine?
- Inactivated▶️inducing neutralizing antibodies againts hemagglutinin antigen▶️❌binding of hemagglutinin to sialylated receptors on the host cell membrane (humoral response)
- Live-attenuated▶️MHC class I antigen-processing pathway▶️cytotoxic CD8+ T lymphocytes▶️kill infected cells (CMI and humoral response)
What type of hypersensitivity reaction is the acute hemolytic transfusion reaction? what is the mechanism?
- Antibody-mediated (type II) hypersensitivity reaction - Minutes to hours.
- Anti-ABO antibodies (mainly IgM)→bind Ag on donor RBC→complement activation►anaphylotoxins (C3a, C5a)→vasodilatation and shock; MAC formation (C5b-C9)→complement-mediated cell lysis
Symptoms of acute hemolytic transfusion reaction.
- Fever, chills, hypotension, shock, hemoglobinuria, dyspnea, chest and/or back pain
- May develop DIC, renal failure
What do you suspect in a patient with recurrent sinopulmonary or GI tract infections, autoimmune disease associated and anaphylactic reaction during blood products transfusion? Why do they have that anaphylactic reaction?
- Selectively IgA deficiency▶️most common immunodeficiency
- Failure of B cells to differentiate in IgA-secreting plasma cells▶️Severe IgA deficiency▶️forms IgE againts IgA▶️blood products have IgA
Uses of Southwestern blotting. Examples.
- Detection of DNA-binding proteins→transcription factors (c-Jun, c-Fos), nucleases, histones
What is the difference between lung and intraabdominal solid organ (kidney) chronic rejection?
Chronic lung transplant rejection▶️inflammation of the small bronchioles⏩bronchiolitis obliterans
- Chronic rejection in renal transplant▶️primarily vascular obliteration
- Accelerated atherosclerosis (heart)
- Chronic graft nephropathy (kidney)
- Vanishing bile duct syndrome (liver)
Where and by whom is made the positive and negative selection of T-lymphocyte? In which each process consists?
- Positive selection (thymus-cortex)→thymic cortical epithelial cells►TCR bind self MHC survive. insufficient affinity→apoptosis
- Negative selection (thymus-medulla)→thymic medullary epithelial cells and dendritic cells►TCR bind with high affinity self MHC→apoptosis [eliminate autoreactive T cells]
How may you identify clinically chédiak-higashi syndrome?
- Immunodeficiency→recurrent pyogenic infections by streptococci and staphylocci
- Partial albinism
- Neurologic dysfunction→nystagmus, peripheral and cranial neuropathies
- Infiltrative lymphohystiocytosis
*Autosomal recessive
Pathogenesis of chédiak-higashi syndrome.
Defect in lysosomal trafficking regulator gene (LYST)→microtubule dysfunction in phagosome-lysosome fusion in neutrophils
Findings in peripheral blood smear of chédiak higashi syndrome.
Giant (lysosomal inclusions) cytoplasmic granules in neutrophils, monocytes and platelets
Type of hypersensitivity reaction that is Goodpasture syndrome? Another examples.
Hypersensitivity type II
- Goodpasture syndrome, rheumatic fever, hyperacute transplant rejection→Abs bind to cell surfaces►(+) complement, Fc receptor mediated inflammation
- Myasthenia gravis, Graves disease→Abs bind to cell surface receptors►cellular dysfunction
Pathogenesis of ataxia-telangiectasia. Clinical presentation associated.
- Defect in ATM gene→fail to repair broken dsDNA►cell cycle arrest (hypersensitivity to ionizing radiation)
- Triad: Ataxia, Angioma (telangiectasia), IgA deficiency (recurrent sinopulmonary infections)
- ↑Risk of cancer (leukemia, lymphoma)
Advantage of innactivated polio vaccine respect oral polio vaccine.
- Oral polio vaccine (OPV)→can revert to a fully virulent form►vaccine-associated paralytic poliomielitis; ability to produce contact immunity by shedding vaccine virus on stool (IgA mucosa immunity); more durable CMI.
- Inactivated polio vaccine (IPV)→lower incidence of complications, cannot revert to a virulent form (killed virus - used in developed countries)
