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Antigen Presentation

• MHCII picks up an antigen from the phagolysosome during antigen presentation by phagocytes, but not epithelial cells.

Complement Activation Pathways

• The adaptive immune response is needed for activation of any complement pathway.
• The inflammatory response is triggered by C3a and C5a.
• Complement protein C3b is needed as part of the C5 convertase.
• A molecule from your blood serum must bind the surface of a pathogen.
• The MAC is formed from C5b and C6 - C9.

Bacterial Response to Phagocytosis

• Bacteria produce leukocidins to respond to phagocytosis.

MHC Class II Receptors

• MHC Class II receptors are found only on phagocytes and B-cells

Interferon Action Against Viral Infections

• Interferon is produced in virus-infected cells, inducing antiviral proteins (AVP) in neighboring cells.

Antigen Presenting Cells

• Macrophages (phagocyte) and B cells (lymphocyte) are both antigen-presenting cells (APCs).

Interferon Defense System

• Interferon induces the production of antiviral proteins in adjacent cells

Complement Activation Systems

• Properdin is required in order to stabilize the C5 convertase
• Diapedesis is induced by peptide C3a
• C3b opsonizes foreign cells for phagocytosis
• A pore complex is assembled and inserted into a foreign cell to lyse it
• PMNs are recruited to the site of complement activation by peptide C5a

Bacterial Antioxidant Production

• Bacteria produce antioxidants to survive the harsh environment inside the phagolysosome.

Chronic Bacterial Infection Symptoms

• Clumps of infected macrophages and TH cells are seen in the patient's tissues with a chronic infection of bacteria living and dividing inside the phagolysosome.

Antigen Presentation in Dendritic Cells

• MHCII picks up an antigen from the phagolysosome during antigen presentation by dendritic cells, but not by epithelial cells.

Consequences of Activating Complement Cascade

• Peptide C3a induces B cells to produce antibodies that attach to the bacterium

Alternate Complement Pathway

• The alternate complement pathway is activated even before the humoral immune response is active

Granuloma Formation Requirement

• Persistent antigen presence inside macrophages is required for granuloma formation

Phagocytes

• An antigen-presenting cell could be considered a phagocyte.

MHC II in Exogenous Antigen Presentation

• MHC2 passes through the endocytic vesicle on its way to the cell surface, which is why it is mainly for presentation of exogenous antigens

Opsonization Purpose

• The purpose of the immune system to opsonize bacterial cells is to add surface features to the bacterium, which makes it easier for cells to recognize it

Granuloma Formation Components

• Granuloma formation involves cytokines, macrophages, bacteria, and T cells

MHC-II Characteristics

• MHC-II mainly displays antigens from the phagolysosome

Interferon Production

• Interferon is produced during an infection through a second-messenger pathway, induced when viral RNA binds to an RLR receptor.

Granuloma Formation Infections

• Bacteria prevent lysosomes in infected macrophages from fusing with phagosomes is true of infections that are characterized by granuloma formation

Toll-Like Receptor Function

• Toll-like receptor allows macrophages and dendritic cells to bind specifically to pathogens

Viral Infection Signal

• Double-stranded RNA is typically recognized by the immune system to signal a cell has been infected by a virus

Interferon Function During Viral Infection

• Interferon functions as an inducer that turns on genes for antiviral proteins in neighboring cells during a viral infection.

Bacterial Evasion of Phagosome Destruction

• Bacteria evade the oxidative burst by preventing lysosome fusion to a phagosome.

Leukocidin Definition

• A leukocidin is a toxin produced by bacteria to kill macrophages.

MHC Class I Antigen Presentation

• Antigen presentation on MHC class I requires protein digestion by the proteasome

MHC Class II Antigens

• Antigens displayed on MHC class II come from the phagolysosome of the cell that displays them.

Antibodies in Innate Immunity

• Antibodies activate the synthesis of antimicrobial peptides in the innate immune response.

MHC-I vs MHC-II

• MHC-I can display self-antigens on the surface of uninfected cells

Interferon α and β

• Interferon α and β are released from a cell to bind to receptors on nearby cells

Complement Activation Pathways Difference

• The complement activation pathways differ in how C3 and C5 proteins are hydrolyzed

Dendritic Cell Binding to Pathogen

• When a pathogen binds specifically to a dendritic cell (DC), the pathogen is engulfed, and the DC produces co-stimulatory molecules.

Bacterial Survival Inside Phagolysosome

• Bacteria survive inside the phagolysosome because they produce antioxidants.

Endogenous vs Exogenous Antigen Presentation

• Endogenous antigens are processed by the proteasome, exogenous by the phagolysosome

Interferon Action on Viral Replication

• Interferon prevents viral replication by signaling cells to be ready to apoptose if a virus invades

Complement Molecule Function

• C5a functions as a chemokine signaling molecule.

Phagolysosome Components

• Peroxides and antimicrobial complement peptides are produced inside a phagolysosome.

Granuloma Diagnosis

• A patient has a granuloma, and may need long term antibiotics to treat it

Complement-Associated Term

• Lectin does not digest the C5 protein