Immunodeficiencies Flashcards
Name the 2 major consequences of asplenia.
1) Increased susceptibility to encapsulated bacterial pathogens (S. pneumonia, H. influenzae, Neisseria)
2) Elevated susceptibility to septic infections by these pathogens (because spleen is one of the body’s blood filters and has macrophages that take up bacteria in the blood).
How to you help someone with asplenia not get infected?
Those without a spleen should be given vaccinations for encapsulated bacterial pathogens and begin taking antibiotics prophylacticly is they show symptoms of respiratory infection or fever.
“NK cell deficiencies” can be a result of what genetic deficiencies?
- Defective formation of cytoplasmic granules
- Defective perforin
- Defects in development of bone marrow
Those persons with NK cell deficiencies suffer from increased levels of infections by what pathogens?
1) Varcella Zoster Virus, Herpes Virus, Cytomegalovirus, Epstein-Barr Virus
2) Mycobacterium opportunistic pathogens
3) Trichophyton (fungus that leads to hair, skin, and nail infections)
What is called X-linked hypohydrotic ectodermal dysplasia and immunodeficiency known as?
NEMO deficiency
What is NEMO deficiency?
a genetic defect in a protein (IKKγ or NEMO) that is required for NFkB activity (an important transcription factor for controlling cytokine expression in response to TLR signaling)
What are physical characteristics of a patient with NEMO deficiency?
- Deep-set eyes
- Sparce and/or fine hair
- Conical or missing teeth
- Skin condition that leads to blistering and changes in skin color (incontinentia pigmenti)
Those with NEMO deficiency suffer from increased rates of viral and bacterial infections, but what specific bacterial pathogen?
Mycobacterium avium
How do you treat someone with NEMO deficiency?
biweekly injections of gamma globulin from a healthy donor or a bone marrow transplant.
What is the genetic basis of Leukocyte Adhesion Deficiency (LAD)?
Defective CD18 (adhesion molecule) leading to defective migration of phagocytes into infected tissue
Those with LAD have an increased susceptibility to what pathogens?
Widespread infections with capsulated bacteria
What is the most telling clinical sign of LAD?
delayed detachment and sloughing of umbilical cord
What is Myeloperoxidase Deficiency?
Impaired production of HOCL by neutrophils and macrophages, so impaired killing of phagocytosed bacteria.
Those with Myeloperoxidase Deficiency have an increased susceptibility to what pathogens?
Chronic bacterial and fungal infections
What is Glucose-6-Phosphate Dehydrogenase Deficiency?
Deficiency of G6PD, so no respiratory burst, and impaired killing of phagocytosed bacteria.
Those with Glucose-6-Phosphate Dehydrogenase Deficiency have an increased susceptibility to what pathogens?
Chronic bacterial and fungal infections, with anemia being induced by some agents
What is Chronic granulomatous disease?
Defective NADPH oxidase leading to impaired killing of phagocytosed bacteria (phagocytes cannot produce O2-).
Those with Chronic granulomatous disease have an increased susceptibility to what pathogens?
Chronic bacterial and fungal infections, leading to formation of granulomas
What is Chediak-Higashi Syndrome?
Defect in vesicle fusion leading to impaired phagocytosis due to inability of endosomes to fuse with lysosomes
Those with Chediak-Higashi Syndrome have an increased susceptibility to what pathogens?
Recurrent and persistent bacterial infections, granulomas.
What are some clinical manifestations of Chediak-Higashi Syndrome?
Effects on many organs
albinism
many patients die before adulthood
What are the two major types of neutropenia?
- Severe Congenital Neutropenia (Kostmann syndrome)
- Cyclic Neutropenia
What is the cause of Severe Congenital Neutropenia (Kostmann syndrome)?
Non-functional G-CSF, leading to failure of neutrophils to colonize, and low neutrophil counts (less than 500)
What is the cause of Cyclic Neutropenia?
Defect in Ela-2 (which encodes elastase) and causes cyclic episodes of neutropenia every 2-4 weeks
Those with neutropenia have an increased susceptibility to what pathogens?
Bacterial infections, even normal flora microbes
Those deficient in C1, C2, and C4 have what problems? Why?
Immune-complex disease, because no opsonization of antibody-coated antigen by classical pathway
Those deficient in C3 have what problems? Why?
increased susceptibility to encapsulated bacteria, because they cannot activate any complement cascades
Those deficient in C5-C9 have what problems? Why?
Susceptibility to Neisseria, because they cannot form MAC
Those deficient in Factor D have what problems? Why?
Susceptibility to capsulated bacteria and Neisseria, because they cannot perform the alternative pathway
Those deficient in Factor I have what problems? Why?
Susceptibility to capsulated bacteria and Neisseria, due to constant C3 convertase that uses up all of the C3 needed to start the complement cascade
Those deficient in DAF/CD59 have what problems? Why?
Autoimmune-like conditions including paroxysmal nocturnal hemoglobinuria (RBC lysis) that are life threatening and cause hemolytic anemia, red urine, and thrombosis.
Missing anchor protein for:
DAF- dissociates C3 convertase enzymes
CD59- prevents C9 from joining, NO MAC
Those deficient in C1INH have what problems? Why?
HANE (edema due to too many anaphylatoxins), because you do not have the enzyme that binds to C1r/C1s and forces them to dissociate from C1q–stopping classical pathway
Those deficient in MBL have what problems? Why?
Recurrent Severe Infections (especially bacterial), because there is no activation of lectin complement pathway, acute phase response impaired
What is the genetic basis for X-linked agammaglobulinemia?
Defect in Bruton’s tyrosine Kinase, so NO signal transduction for B cell development, so few B cells