Complement System Overview

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Which cell types are involved in classical macrophage activation?

Neutrophils and Monocytes (correct)

Mast Cells

Monocytes/Macrophages

Dendritic Cells

What induces alternative macrophage activation?

TLRs

Histamine

IL-4 and IL-13 (correct)

IFN-γ

Which cells serve as sentinels in tissues and play a role in initiating inflammation?

Mast Cells

Dendritic Cells (correct)

Monocytes/Macrophages

Neutrophils

What are the main functions of dendritic cells in the immune system?

Serving as bridges between innate and adaptive immunity Signup and view all the answers

Mast cells are activated by which of the following mechanisms?

Microbial products binding to TLRs Signup and view all the answers

What do mast cells release when activated?

Vasoactive amines like histamine Signup and view all the answers

What is the primary function of antimicrobial peptides Defensins and cathelicidins?

Disrupt the outer membranes of bacteria and some viruses Signup and view all the answers

Which of the following is a function of epithelia in innate immunity?

Presence of Intraepithelial T Lymphocytes Signup and view all the answers

What is a unique feature of Intraepithelial T Lymphocytes' antigen receptors?

Composed of γ and δ chains Signup and view all the answers

Why are Neutrophils considered as early responders in the immune system?

They are recruited to sites of infection and act quickly Signup and view all the answers

Which type of phagocyte survives in tissues for long periods?

Macrophages Signup and view all the answers

What do Phagocytes like Monocytes/Macrophages do to microbes at sites of infection?

Ingest microbes for intracellular killing Signup and view all the answers

What is the main characteristic that activates Natural Killer (NK) cells?

Expression of ligands for activating receptors Signup and view all the answers

Which pathway of the complement system is activated by mannose-binding lectin (MBL) binding to carbohydrate ligands on microbes?

Lectin pathway Signup and view all the answers

What happens to the inhibitory receptors of NK cells when class I MHC expression is reduced on infected cells?

They are not engaged Signup and view all the answers

Which pathway of the complement system is triggered by antibodies binding to microbes?

Classical pathway Signup and view all the answers

Why is the alternative pathway of the complement system not controlled on microbial surfaces?

Absence of complement regulatory proteins on microbes Signup and view all the answers

Which component of the immune system do complement proteins belong to?

Innate immunity Signup and view all the answers

What is the role of C-reactive protein (CRP) in innate immunity?

Opsonizing microbes for phagocytosis Signup and view all the answers

Which cells are the principal sources of cytokines in innate immunity?

Dendritic cells Signup and view all the answers

What are the principal cytokines involved in recruiting blood neutrophils and monocytes to sites of infection?

Tumor necrosis factor Signup and view all the answers

What do cytokines do in immune and inflammatory reactions?

Mediate immune and inflammatory reactions Signup and view all the answers

What is the main effect of TNF and IL-1 in innate immunity?

Inducing fever Signup and view all the answers

What is the central component of all complement pathways?

C3 protein Signup and view all the answers

Which complement protein is responsible for recruiting and activating downstream complement proteins on the microbial surface?

C3a Signup and view all the answers

What function does C5a mainly serve in the complement system?

Inflammation Signup and view all the answers

Which plasma protein in innate immunity recognizes microbial carbohydrates?

MBL Signup and view all the answers

What is the function of surfactant proteins in the lungs with respect to innate immunity?

Protect airways from infection Signup and view all the answers

What is the main consequence of the formation of the membrane attack complex (MAC) on a microbe?

Causes cell lysis Signup and view all the answers