Immunology - Lecture 11 (midterm review)

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Questions and Answers

Which type of immune cell is NOT classified under the innate immune system?

NK cells

B cells (correct)

Macrophages

Neutrophils

What is primarily recognized by Pattern Recognition Receptors (PRRs) in innate immune cells?

Pathogen-associated molecular patterns (correct)

Cytokines

Antigens

Adaptive immune responses

What is the role of the Complement system in the innate immune response?

To promote phagocytosis and inflammation (correct)

To produce antibodies

To activate T cells

To neutralize toxins

Which of the following are part of the chemical barriers in the innate immune system?

Enzymes Signup and view all the answers

Which of these immune cells is specifically known for targeting intracellular pathogens?

T cells Signup and view all the answers

Which immune cell component is involved in both innate and adaptive immunity?

Dendritic cells Signup and view all the answers

What is NOT a function of macrophages in the innate immune response?

Production of antibodies Signup and view all the answers

What differentiates the alternative pathway from other pathways of complement activation?

It is activated by pathogen surfaces Signup and view all the answers

Which protein is responsible for ligating the processed broken ends of DNA?

DNA ligase IV Signup and view all the answers

What are the three properties affected by MHC polymorphism?

Range of peptide bound, conformation of bound peptide, interaction with TCR Signup and view all the answers

What is the role of dendritic cells in lymph nodes?

To process and present antigens Signup and view all the answers

What signifies the concept of codominance in MHC diversity?

Both alleles are expressed equally Signup and view all the answers

What initiates T cell activation?

Binding of TCR to ligand Signup and view all the answers

Which component is crucial for TCR signaling?

TCR signaling network Signup and view all the answers

What is the primary function of antigen processing and presentation?

Activation of T cells Signup and view all the answers

What is the consequence if TCR does not properly bind to peptide-MHC complexes?

Cellular apoptosis Signup and view all the answers

What do the letters V, D, and J represent in the context of receptor gene segments?

Variable, Diversity, Joining Signup and view all the answers

Which enzyme is specifically responsible for creating double-stranded breaks during V(D)J recombination?

V(D)J recombinase Signup and view all the answers

What role does Artemis play in the process of V(D)J recombination?

Opens hairpins at coding junctions Signup and view all the answers

Which of the following proteins bind to the DNA breaks during the joining process of V(D)J recombination?

KU70 and KU80 Signup and view all the answers

What happens during the hairpin opening step of V(D)J recombination?

Endonucleases open hairpins and nucleotides may be added or removed Signup and view all the answers

What type of DNA repair process is utilized to join broken ends during V(D)J recombination?

Nonhomologous end joining Signup and view all the answers

Which of the following statements about RAG proteins is true?

RAG1 and RAG2 are crucial for the cleavage step Signup and view all the answers

Which sequence is crucial for guiding the rearrangement of V, D, and J gene segments?

Recombination signal sequences (RSS) Signup and view all the answers

Study Notes

Innate Immune System Recap

Physical barriers include epithelial and mucosal linings, mucus, and tears.
Chemical barriers include acidic pH, enzymes, and antimicrobial peptides (AMPs).
Microbiological barriers include the microbiota.
Innate immune cells include macrophages, neutrophils, and natural killer (NK) cells.
Adaptive immunity is mediated by B cells and T cells.

Pathogen Pattern Recognition and Innate Immune Cell Function

Pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs) present on pathogens.
Toll-like receptors (TLRs) recognize PAMPs on the cell surface.
Nod-like receptors (NLRs) recognize intracellular PAMPs.
RIG-I-like receptors (RLRs) recognize viral RNA in the cytoplasm.
PRR signaling triggers the production of cytokines and chemokines, which activate other immune cells and initiate inflammation.

Innate Immune Cell Function

Macrophages engulf and destroy pathogens through phagocytosis.
Neutrophils are short-lived phagocytic cells that release antimicrobial substances.
NK cells destroy infected cells and tumor cells.

Complement Activation and Innate Immune Cell Action

The complement system is a group of proteins that can directly kill pathogens or enhance other immune responses.
The alternative pathway of complement activation is triggered by the presence of pathogens on surfaces.
Complement proteins form the membrane attack complex (MAC), which disrupts the integrity of pathogen membranes.
Complement also enhances phagocytosis by opsonization.

The Acute-Phase Response and Complement Activation

The acute-phase response is an early innate immune response to infection or injury.
It involves the production of acute-phase proteins by the liver, such as C-reactive protein (CRP).
CRP activates the classical pathway of complement activation.

The Adaptive Immune System

The adaptive immune system is characterized by its specificity and memory.
T cells recognize antigen presented by MHC molecules on antigen-presenting cells (APCs).
B cells produce antibodies that recognize and neutralize pathogens.

Lymphocyte Development and Receptor Gene Recombination

Lymphocyte development occurs in primary lymphoid tissues, such as the bone marrow and thymus.
Recombination of receptor genes creates a vast diversity of antigen receptors.
V(D)J recombination is a process that generates diversity in the antigen-binding sites of T cell receptors (TCRs) and B cell receptors (BCRs).

Antigen Recognition and Presentation

MHC molecules present peptides derived from pathogens on the cell surface.
TCRs recognize specific peptide-MHC complexes.
BCRs bind to intact antigens.

T Cell Activation

TCR signaling triggers the activation of T cells.
Co-stimulatory signals, provided by molecules such as CD28, are required for full T cell activation.
Activated T cells proliferate and differentiate into effector T cells.

B Cell Activation

B cell activation involves antigen binding to the BCR and co-stimulatory signals.
Activated B cells differentiate into antibody-secreting plasma cells.
Antibody-mediated immunity is a major component of the adaptive immune response.

MHC Diversity

MHC molecules are highly polymorphic, which contributes to the immune system’s ability to recognize a wide array of antigens.
MHC polymorphism can influence the range of peptides bound, the conformation of the bound peptide, and the interaction of the MHC molecule with the TCR.

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Description

This quiz covers the key components of the innate immune system, including physical, chemical, and microbiological barriers. It also discusses the roles of various innate immune cells such as macrophages, neutrophils, and natural killer cells, as well as the mechanisms for pathogen pattern recognition. Test your knowledge on immune responses and cell functions essential for defenses against pathogens.