Immunology Overview

What is the role of complement?

Promotes inflammation, opsonization, and pathogen clearance

What activates complement?

C3 convertase cleaves C3 → C3a + C3b

What are acute phase reactants?

Liver-produced proteins that enhance pathogen clearance

What do Toll-like receptors (TLRs) recognize?

General pathogen-associated molecular patterns (PAMPs)

What are the two classes of HLA?

Class I (α chain + β2-microglobulin), Class II (α + β chains)

What do CD8+ T cells do?

Kill virally infected cells

What cytokines are produced by Th1 cells?

IL-2, IFN-γ, TNF-α

What cytokines are produced by Th2 cells?

IL-4, IL-5, IL-6, IL-10, IL-13

What is the role of IL-2?

T cell proliferation

What is the role of IL-4 and IL-13?

B cell activation and class switching to IgG1 and IgE

What is the B cell receptor (BCR)?

Membrane-bound antibody composed of heavy and light chains

What is somatic hypermutation?

Mutation of antibody genes to increase affinity

What is affinity maturation?

Selection of B cells with highest affinity antibodies

What is class switching?

Change in antibody isotype (e.g., IgM → IgG)

Which antibody enhances phagocytosis?

IgG

Which antibodies neutralize toxins?

IgM, IgG, IgA

Which antibodies prevent pathogen adherence?

IgM, IgG, IgA

Which antibodies activate complement?

IgM, IgG

Which antibody crosses the placenta?

IgG

Which antibody sensitizes mast cells?

IgE

Which antibodies are active at mucosal surfaces?

IgA, IgG

Which antibodies are antigen receptors on naïve B cells?

IgM, IgD

What induces immunologic memory?

Exposure to antigen via infection or vaccination

Why do vaccines work?

They prime the adaptive immune system to respond rapidly upon re-exposure

What is sepsis?

Immune overdrive leading to systemic inflammation

Three signals APCs deliver to naive t cells

Activation, Proliferation and Survival, Differentiation