Immunology Flashcards
What does an increase in serum myeloperoxidase indicate?
Myeloperoxidase is found predominantly in PMNs, can increase following inflammation and infection
Anaphylaxis is a result of ____ degranulation, which can be marked by elevated ____
Anaphylaxis = result of widespread basophil and mast cell degranulation, which causes the release of preformed inflammatory mediators including
- Histamine
- Tryptase (relatively specific to mast cells)
What is required for mast cell/basophil degranulation?
Multiple IgE antibodies become cross-linked –> aggregation of the high-affinity IgE receptor –> activation of non-receptor tyrosine kinases, intracellular cascade –> degranulation
How do IFN alpha and beta help the host to respond to viral infections?
IFN A and B help to suppress viral replication by halting protein synthesis and promoting apoptosis of infected cells, thus limiting the ability of viruses to spread through the tissues
What is the mutation in Ataxia-Telangiectasia
The ATM gene is mutated, responsible for DNA break repair
Sx of AT: cerebellar ataxia, telangiectasias, predisposed to upper airway infections (IgA deficiency)
B lymphocytes: effective vs intracellular organisms?
NO
Which type of immune cells and cytokines work together to wall off TB within a caseous granuloma?
CD4+ T helper cells and macrophages
Cytokines = IFN-gamma, IL-12, TNF-alpha
What serologic marker is indicative of HBV infectivity?
HBeAg
envelope
Which strep pneumo vaccine (polysaccharide or conjugate) do you give to an infant? Why?
Conjugate.
Conjugate vaccines are more strongly immunogenic due to both B and T cell recruitment. The polysaccharide vaccine is poorly immunogenic in infants d/t their relatively immature humoral ab response
What disease is characterized by oculocutaneous albinism, pyogenic infections, and progressive neurologic dysfunction?
Chediak-Higashi Syndrome
Congenital heart disease + dysmorphic facies + hypocalcemia
DiGeorge’s Syndrome
Severe bacterial and viral infections in infancy + chronic diarrhea + mucocutaneous candidiasis
Severe Combined Immune Deficiency (SCID)
lab studies with low-absent CD3+ cells and hypogammaglobulinemia
Recurrent infections that worsen with age + easy bleeding + eczema
Wiskott-Aldrich Syndrome
What are the key cells in delayed hypersensitivty (Type IV)
Macrophages, CD4 helper cells, CD8 cytotoxic T cells
In what part of the cell is antigen loaded in MHC CI vs MHC CII
MHC CI: antigen loaded in RER after delivery via TAP
MCH CII: Antigen loaded following release of invariant chain in an acidified endosome
What receptor activates the extrinsic pathway of apoptosis (key to ridding the body of autoreactive lymphocytes)?
Mutations in Fas receptor or Fas Ligand
Which cytokines produced by Th2 cells promotes isotype switching to IgE?
IL-4 and IL-13
What two roles do eosinophils play in the immune system?
1) Type I hypersensitivity rxns – synthesize prostaglandins, leukotrienes, and cytokines that contribute to the inflammation seen in the late phase of TI hypersensitivity
2) Parasitic Defense – proliferation and activation via IL 5 from Th2 and mast cells. Eos degranulation releases major basic protein to destroy the antibody-bound parasite (an example of antibody dependent cell-mediated cytotoxicity)
What happens in hemolytic disease of the newborn?
Fetal erythrocyte opsonization by maternal antibodies
Acute transplant rejection occurs via _____
sensitization of host T lymphocytes against donor MHC/HLA antigens
In a reaction to a transfusion: fever/chills, hypotension, dyspnea, chest/back pain, hemoglobinuria within minutes to hours
= Acute hemolytic transfusion reaction
Type II hypersensitivity; d/t ABO mismatch
Anaphylaxis during blood transfusions + h/o autoimmune disease/atopy + airway/GI infections
Selective IgA deficiency
Most often = asymptomatic
Define Negative vs Positive Selection in T cell maturation
Negative Selection: elimination of T cells that bind self MHC or self antigens with too much affinity
Positive Selection: T cells that are able to bind self MHC are allowed to survive; T cells must be able to recognize self
Recurrent respiratory infections + dextrocardia + infertility
Kartagener Syndrome
A form of primary ciliary dyskinesia
What type of transplant rejection has “dense interstitial lymphocytic infiltrate”
Acute (timeline = weeks to months)
What is the cell surface marker for the monocyte/macrophage cell lineage?
CD14
Who secretes IL-2? What are its effects?
IL2 is secreted by T helper cells
- stimulates growth of CD4 and CD8 T cells
- stimulates growth of B cells
- activates NK cells and monocytes
Where are T lymphocytes and Dendritic Cells found in the lymph node?
Paracortex (between follicles and medulla)
- this is the area of the LN that becomes enlarged during adaptive cellular immune responses
Henoch-Schonlein Purpura is a…
IgA immune complex-mediated vasculitis (Type III hypersensitivity)
SX: palpable lower extremity purpura, arthralgias, hematuria, abdominal pain (+/- intasussception) following infection
What are the key cytokines that activate Th1 cells?
IL 12 and IFN-gamma
What causes leukocyte adhesion deficiency?
Absence of CD18 antigens necessary for the formation of integrins –> impaired PMN migration and chemotaxis
recurrent bacterial skin and mucosal infections without pus formation (no PMNs at infection sites)
What causes Hyper IgM syndrome?
(most commonly) due to lack of CD40L on T lymphocytes or genetic deficiency of enzymes responsible for DNA modification necessary for isotype switch.
SX: lymphoid hyperplasia and recurrent sinopulmonary infections
Which cytokines secreted by Th2 cells activate eosinophils and promote IgA synthesis?
IL-5
Secretion of which cytokine from helper T cells recruits bone marrow stem cells?
IL-3
What is serum sickness?
A type III hypersensitivity = vasculitis from tissue deposition of circulating ICs
fever, pruritic skin rash, arthralgias, low serum complement
