what differeniated macrophage types exist throughout body?

• microglia (CNS)
• kupffer cells (liver)
• alveolar macrophages (lungs)
• osteoclasts (bone)
• dendritic cells (skin, lymph nodes)

• TLRs
• N-formyl methionyl receptor
• mannose receptor

innate receptors bind to structures shared by CLASSES of microbes

encode in germline; limited diversity

also, all cells of the same lineage express the exact same receptor

• alert adaptive immunity about microbe and stimulates adaptive immunity to make them more optimally effective
• as the initial response to microbes, there is potential elimination of microbe, before adaptive immunity even responds
• effector mechanisms, even once adaptive is stimulated, help to eliminate microbe

• cationic, cysteine rich antimicrobial peptides
• broad-spectrum antibiotic
  • gram +/- bacteria
  • fungi
  • enveloped viruses
  • mycobacterium
• found at mucosal surfaces (GI, vaginal, trachea, etc), skin

• initial binding of peptides (+) to membrane (-)
• insertion into membrane
• creation of an inserted pore in the microbe membrane by taking advantage of charge repulsion between the collaborating defensin peptides
• loss of small molecule gradients

• induces viral resistance
• increases MHC I expression and Ag presentation
• macrophage activation
• NK activation

type I IFN is secreted in LARGE amounts by cells infected with virus, in response to presense of dsRNA within the cell

1. tethering: selectins slow down neutrophils in blood vessel
2. activation: chemokines from site of infection activate the PMN to express a high affinity receptor for integrin/CAM adherence
3. adhesion/arrest: leukocyte completely slowed via integrin/CAM
4. transendothelial migration (diapedesis) and movement towards infection site

these complement products act on blood vessels to increase vascular permeability and cell adhesion molecules

increased leakiness allows movement of WBCs and Igs out of vessels and into tissue near site of infection

these molecules are chemotaxis involved, aiding in the migration of macrophages, PMN, and lymphocyte, AND in the activity of macrophages and PMNs

in the blood

growth stimulated with: G-CSF

in the tissue

M-CSF stimulates their growth

what is the receptor for LPS found on macrophage surface?

CD14 (receptor) binds LPS

what are some cytokines secreted by macrophage upon pathogen binding?

• IL 1: vascular perm, lympho activation, tissue damage, fever
• TNF a: vascular permeability, fever
• IL 6: lymphocyte activation (Ig prod); fever
• IL-12: NK/Th1 activation/differentiation

what are examples of acute phase proteins and what stimulates their production?

• bacteria induce macrophage to produce IL6, which acts on liver to produce these acute phase proteins:
  • C reactive
  • serum amyloid
  • fibrinogen
  • mannan-binding lectin
• goal of these proteins: eliminate microbe and provide counter-regulatory response

• made by liver upon IL 6 stimulation

• opsonization of bacteria
• complement activation

• made by liver upon IL 6 stimulation
• binds mannose residues on cell surface of bacterial surfaces (opsonization)
• complement activation

PAMPs are in outer structure of microbe, in the peptidoglycan component of the cell wall

when stained, with Gram staining (crystal violet), they turn dark blue

Gram (-) are those proteins without extensive PG in outer membrane rich with LPS, but with PG sandwiched between OM and IM. They do not pick up the Gram staining.

most pathogenic bacteria are gram negative

work together to initiate signaling cascade when LPS from a gram negative bacteria is bound extracellularly

CD14 (a coreceptor for TLR4) first binds PAMP, and then passes off the PAMP to TLR 4 for full signaling, ending with the upregulation of cytokines

• MyD88
• TRIF

in the MyD88 independent pathway, what important cytokine is produced?

IFN β

• anti viral that stimulates activation of macrophages and NK cells
• production stimulated by IRF-3 (interferon regulatory factor 3), an IFN transcription factor

by using different adapter molecules that activate distinct signaling pathways

how may the variety of TLR response be expanded even further?

they may act with IFNγ receptor

which greatly enhancing the effector functions of the macrophage

• P oxidase -->ROI
• iNOS --> NO
• IL 12, TNF -->inflammation, adaptive immunity
• FGFs --> tissue remodeling
• increased MHC molecules, costimulators -->enhanced antigen presentation

source: macrophages, T cells

function: inflammation, PMN activation, fever, synthesis of acute phase proteins in liver, cachexia, apoptosis

source: macs, some endothelial cells

function: inflammation, coagulation, fever, synthesis of acute phase proteins

source: macs, DCs

function: IFNγ synthesis (NK, T cells), increased cytolytic activity, Th1 differentiation

source:Th1cells, Nks

function: macrophage activation

source: macrophages (a), fibroblasts (b)

function: antiviral activity, increased class I MHC expression, NK cell activation

source: macrophages, T cells (Th2)

function: inhibition of IL12 (macs), downregulates MHC class II expression on macs; B cell activation, proliferation, Ab production

source: macs, T cells

function: liver synthesis of acute phase proteins (serum amyloid protein, fibrinogen, C reactive protein)

• superoxide dismutase (SOD): O2- into H2O2
• MPO(myeloperoxidase): H202-->XO- + H20
• NAPDH-Oxidase: O2-->O2-(superoxide)
  • if missing, will develop CGD
• Glutathione reductase: keeps supply of reduced NADPH for reaction with O2 to create superoxide ion

what does it take to make macrophage fully microbicidal/tumoricidal?

• IFN gamma
• LPS or pathogen binding

what type of PAMP does CD14/TLR4 + MD2 recognize?