Immunology Flashcards
Delayed-type hypersensitivity (Type IV) reactions
Mediated by T-lymphs (NO Abs!); 1-2 days afterwards; Ag presented to Th lymph on MHC-II -> IFN-gamma release -> macrophage recruitment –> “walling off…4 T’s - T lymphs, transplant reject, TB test, touching (contact dermatitis). Sarcoidosis
ACID hypersensitivity
Anaphylactic and Atopic, Cytotoxic, Immune complex, Delayed
Type I hypersensitivity
First and Fast; Free Ag cross-links IgE on pre-sensitized mast cells and basophils -> vasoactive amines (histamine) + tryptase (often used as marker); preformed Ab = fast; delayed = production of leukotrienes.
Type II hypersensitivity
Auto-Ab-mediated - IgM and IgG bind to a FIXED Ag on “enemy” cell; Opsonization, complement-mediated lysis (MAC), Ab-dependent cell-mediated death (NK or macros); Goodpastures. Test via Coombs. Direct Coombs test for Ab’s that have bound to patient’s RBC’s. Indirect for Ab’s that could potentially bind RBCs.
Graft-v-host disease
Mediated by T-lymphocytes; CD4+, CD8+. Occurs after bone marrow, liver, non-irradiated blood transfusion. 1 week; Rash, jaundice, diarrhea. Helpful for leukemia pts
What immune cell most heavily involved in TB?
Caseating granulomas (Langerhans giant cells) mediated by macrophages to present Ag to CD4+ Th1 -> epitheliod cells -> Langerhans giant cells (nuclei in horseshoe)
Cytotoxic T-cell?
CD8+ cell. In Eighth grade, “Cuz i’m toxic.” Granzyme B = serine protease.
What region of lymph node enlarged w/ proliferating T-cells?
Paracortex
Neutrophil chemotaxis induced by what?
IL-8 from macrophages. (Others are leukotriene B, C5a). Movie it [EIGHT] neutrophils! Clean UP on Aisle 8.
What is the f(x) of lymph node follicle?
B lymphocyte localization and proliferation. Primary - dense, dormant. Secondary - pale germinal center. In agammaglobulinemia, germinal centers AND primary folicles do not form. B cells are my best friend! (F for follicle). Monoclonal expansion, somatic hypermutation, selection for the best.
Type III hypersensitivity
Deposition of IC’s (Antibody-Ag-complement) -> complement activation (C5a) -> neutrophils that damage. Serum sickness, PSGN, lupus nephritis. Arthus reaction (local subacute following intraderminal injection - edema, necrosis, activation of complement)
MHC I
Presents ENDOgenous Ag on surface: self, tumor, or Ag 2/2 to viral infection. (Protein, proteasome, RER - where loaded via B2-microglobulin). HLA-A, HLA-B, HLA-C.
MHC II
Presents EXOgenous. (Me first, then Outside). Ag taken by APC’s -> Endosomes where meet MHC II - INVARIANT chain -> replaces invariant chain w/ ACIDification + HLA-DM -> presentation to T-helper cells. HLA-DR, DP, DQ. alpha and beta chain (polypeptides).
TxA2 (thromboxane) f(x)?
Vasoconstriction, PLT aggregation. TAXIS go in constricted and aggregate areas.
PGI2 f(x)? (prostacyclin)
Vasodilation, inhibition of PLT aggregation
T-cell maturation
In the thymus. Subcapsular zone - “double negative”. Cortex becomes “double positive” (alphabetaTCR+, CD3+, CD4+, CD8+). Positive selection w/ Cortical epithelial cells to ensure sufficient recognition of its own MHCI and MHC II. Now differentiated to to become single positive CD4 or CD8. Then negative selection by medullary epithelial and dendritic cells to make sure not overly sensitive to self.
Lymph node medulla?
Consists of medullar cords (close packed lymphocytes and plasma cells) and medullary sinuses. Macrophages and reticular cells.
Lymph node paracortex?
Houses T-cells. Where T and B cells enter from blood. diGeorge underdeveloped. T cells are ParaTroopers.
Para-aortic lymph nodes drain what?
Testes, ovaries, kidneys, uterus
GI lymph node drainage system?
Celiac for liver, stomach, spleen, pancreas, upper duodenum. Sup. mesenteric for lower duodenum, jejunum, ileum, colon to splenic flexure. Inf. mesenteric for colon from splenic flexure to rectus. Internal iliac for lower rectum to anal canal (above pectinate), bladder, vaginal, prostate.
Spleen dysfunction pathogenesis
Decreased IgM -> decreased complement activation -> decreased C3b opsonization -> inc. susceptibility to encapsulated organisms (SHiNE SKiS).
MHC I and MHC II bind to what receptors?
Tee Receiving Option #1 AND 2 = OCHO-CUATRO. 1 binds to TCR and CD8+. II binds to TCR and CD4+.
MHC I subtypes associated with disease?
HLA B27 = Seronegatives (Psoriatic arthritis, Ankylosing spondylitis, IBD, Reactive arthritis). HLA A3 - hemochromatosis.
MHC II subtypes?
DQ2/DQ8 - No Dairy Queen for Celiacs. DR4 = RA, DMI.