Immunology Flashcards
Type I interferons (a and B) are synthesized by most human cells in response to viral infections, and bind to type I interferon receptors found on ifnected and neighboring cells (acutocrine/paracrine) signaling resulting in transcription of antiviral enzymes capable of halting protein synthesis, such as RNase L and protein kinase R (inactivates EF-2)
These enzymes act only in the presence of double stranded RNA, which forms in infected cells as a result of viral replications. As a reuslt, normal metabolism and protein synthesis can continue in uninfected cells but is selcetively inhibited in virally infected cells
Interferons a and B induce MHC class I expresison on all cells and stimulate NK and cytotoxic T cells to increase apoptosis
Interferon y is a type II interferon produced mainly by T cells and NK cells to promote TH1 differnetiation, inreasing expression of class II MHC molecules on APCs. But note that virally infected respiratory epithelial cells secrete interferons a and B, not interferon y.
Type I rxns- IgE; basophils, mast cells; E.g. anaphylaxis, allergies
Type II rxns- IgG and IgM autoantibodies and complement activation; NK cells, eosinophils, neutrophils, and macrophages; E.g. Autoimmune hemolytic anemia, Goodpasture syndrome
Type III rxns- deposition of antibody-antigen complexes; neutrophils; E.g. serum sickness, PSGN, and Lupus nephritis
Type IV rxns: No humoral component; T cells and macrophages; E.g. contact dermatitis, and Tuberculin skin test
Anaphylaxis- In response to a sting/bite, pt will undergo Ab switching to IgE in B lymphocytes, which will bind to receptors of basophils in the blood and mast cells in the tissue
When relevant antigens intercts with cell bound-specific IgE, these Abs will cross-link causing degranulation and relase of histamine, prostaglandins, and leukotrienes
Langerhans cells are the dendritic cells of the skin and act as APCs- these always express MHC class II molecules and the co-stimulatory B7 molecules
They are derived from the myeloid cell line
have a callsic ‘racquet-shaped’ intracytoplasmic granule (aka a Birbeck granule)
Birbeck granule
Triple-combo HIV therapy is recommended for HIV positive pregnant women (as it is for all HIV+ adults) regardless of CD4 count
Usually consists of 2 nucleoside/nucleotide reverse transceriptase inhibitos along with a third drug (protease inhibitor, NNRTI, or integrase inhibitor)
ART should be continued as long as women are breastfeeding
Efavirenz should be avoided in pregnancy
Infants usually receivve weekly of porophylaxis with Zidovudine
Interferon a is used to tx hairy cell leukemia, condyloma acuminata, HBV, and kaposi sacroma
Influenza vaccin include a killed vaccine given via injection and a liver-attenuated vaccine given by nasal spray. All individuals 6+ months old should be vaccinated
Inactivated vaccines work by inducing neutralizing Abs against the hemagglutinin antigen, to prevent viral cell entry
Bacterial or viral source of URTI?
Viral: Typically afebrile with a normal lung exam
Poison ivy, oak, etc. all cause an immune response to URUSHIOL (type IV rxn)
