Immunity to pathogens

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Which effector mechanisms are most effective during responses to intracellular and extracellular pathogens, respectively?

CD8+ T cells and NK cells; complement activation and antibodies
Phagocytosis and NK cells; cytokine production and TLR signaling
CTL’s and macrophage activation; phagocytosis and complement activation (correct)
Interferons and CTL’s; inflammation and antibody production

What specific immune mechanism is crucial in responding to toxigenic bacteria?

CD4+ T cell-mediated cytotoxicity
Neutralization by high-affinity IgG and IgA antibodies (correct)
NK cell-mediated killing
Inflammatory response driven by IL-12 and IL-17

How do bacterial pathogens commonly evade the immune system?

By inducing antigen presentation via MHC class II
By expressing polysaccharide-rich capsules and antigenic variation (correct)
Through overproduction of pro-inflammatory cytokines
By inhibiting NK cell activation through IL-10 secretion

Which type of T helper cells play a significant role in combating fungal infections?

TH1 and TH17 (C) Signup and view all the answers

What is the primary role of Type 1 IFN’s in antiviral responses?

Inhibiting viral replication and enhancing NK cell activity (C) Signup and view all the answers

Which immune system components are most effective against established viral infections ?

CTLs and APC mediated antigen presentation (A) Signup and view all the answers

How do antibodies contribute to antiviral immunity?

By neutralizing viral entry and promoting opsonization (C) Signup and view all the answers

What strategy do viruses use to evade host immune responses?

Antigenic variation and inhibition of MHC class 1 presentation (B) Signup and view all the answers

How can viruses interfere with antigen presentation?

By producing proteins that inhibit MHC class 1 function (D) Signup and view all the answers

What is the primary immune response mechanism against helminth infections?

IgE production and eosinophil activation via TH2 cytokines (B) Signup and view all the answers

What immune mechanisms combat arthropod infestations?

Th2 cytokines promoting mast cell degranulation and eosinophil activation (A) Signup and view all the answers

What are the three main innate immunity mechanisms to eliminate extracellular bacteria?

Complement activation (alternative pathway and lectin pathway), phagocytosis and inflammation Signup and view all the answers

Intracellular Pathogens: Best Defense

Cytotoxic T lymphocytes (CTLs) are the primary weapons against intracellular pathogens like viruses and some bacteria. They directly destroy infected cells.

Extracellular Pathogens: Defense Strategy

Macrophage activation is the key to combating extracellular pathogens. Macrophages engulf and destroy these invaders.

Toxigenic Bacteria: Antidote

High-affinity IgG and IgA antibodies neutralize toxins produced by bacteria, preventing their harmful effects on the body.

Bacterial Evasion Tactics

Some bacteria evade the immune system by forming thick capsules that hide their surface antigens. Others change their surface antigens using a process called antigenic variation.