L2L3

Question 1

Skin

Answer 1

Watertight lipid layer, beta-defensins, and cathelicidins

Question 2

Gut

Answer 2

Low pH, antimicrobial peptides, and mucus

Question 3

Lung

Answer 3

Mucociliary clearance, surfactant proteins, and defensins

Question 4

Classical pathway

Answer 4

Triggered by antibodies binding to antigens

Question 5

Alternative pathway

Answer 5

Triggered by spontaneous hydrolysis of C3

Question 6

Lectin pathway

Answer 6

Triggered by mannose-binding lectin binding to pathogen surfaces

Question 7

Properdin

Answer 7

Stabilizes the C3 convertase of the alternative pathway, enhancing complement activation

Question 8

C3

Answer 8

Central to all three complement activation pathways, amplifies immune response by promoting opsonization, inflammation, and membrane attack complex formation

Question 9

Opsonization

Answer 9

Process where pathogens are marked for phagocytosis by immune cells through antibody or complement binding

Question 10

C1 inhibitor (C1-INH)

Answer 10

Prevents activation of the classical and lectin pathways

Question 11

Factor H and I

Answer 11

Regulate the alternative pathway by degrading C3b

Question 12

Decay-accelerating factor (DAF)

Answer 12

Prevents formation of C3 convertase on host cells

Question 13

CD59

Answer 13

Inhibits the formation of the membrane attack complex (MAC)

Question 14

Phagocytes

Answer 14

Cells that engulf and destroy pathogens, including macrophages, monocytes, and dendritic cells

Question 15

Antigen-presenting cells (APCs)

Answer 15

Cells that process and present antigens to T cells, such as macrophages and dendritic cells

Question 16

Macrophages

Answer 16

Tissue-resident phagocytes producing inflammatory mediators, cytokines, and reactive oxygen/nitrogen species

Question 17

Monocytes

Answer 17

Blood-circulating precursors to macrophages that produce inflammatory mediators and cytokines

Question 18

Dendritic cells

Answer 18

Phagocytic cells producing reactive oxygen species and presenting antigens to T cells

Question 19

Neutrophils

Answer 19

First responders producing reactive oxygen/nitrogen species and antimicrobial peptides

Question 20

Natural killer (NK) cells

Answer 20

Lymphoid-origin cells inducing apoptosis in virus-infected and cancer cells via perforin and granzymes

Question 21

Eosinophils

Answer 21

Cells involved in parasitic infections and releasing histamine-like substances

Question 22

Basophils

Answer 22

Cells involved in allergic reactions and histamine release

Question 23

Mast cells

Answer 23

Cells releasing mediators in early immune responses, particularly in allergic reactions

Question 24

Chemotaxis

Answer 24

Movement of phagocytes toward an inflammatory site guided by chemokine gradients

Question 25

Phagocytosis

Answer 25

Process where phagocytes engulf pathogens, forming phagosomes, which fuse with lysosomes to kill pathogens

Question 26

Pattern recognition receptors (PRRs)

Answer 26

Receptors that detect pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)

Question 27

Toll-like receptors (TLRs)

Answer 27

Membrane-bound PRRs recognizing PAMPs and initiating cytokine secretion

Question 28

RIG-I-like receptors (RLRs)

Answer 28

Cytoplasmic PRRs detecting viral RNA and activating antiviral responses

Question 29

NOD-like receptors (NLRs)

Answer 29

Cytosolic PRRs involved in inflammasome activation and cytokine production

Question 30

Inflammasome

Answer 30

A protein complex converting pro-IL-1_ and pro-IL-18 into their active forms

Question 31

IL-6

Answer 31

Cytokine inducing fever, lymphocyte activation, and antibody production

Question 32

CXCL-8

Answer 32

Chemokine recruiting neutrophils, basophils, and T cells to infection sites

Question 33

TNF

Answer 33

Cytokine causing vasodilation, fever, and endothelium activation

Question 34

IL-12

Answer 34

Cytokine activating NK cells and inducing Th1 differentiation

Question 35

RIG-like receptors (RLRs)

Answer 35

Important PRRs in antiviral responses, recognizing viral RNA

Question 36

Antigen cross-presentation

Answer 36

Mechanism where extracellular antigens are presented on MHC class I molecules to activate cytotoxic T cells

Question 37

Perforin

Answer 37

Protein forming pores in target cell membranes during apoptosis

Question 38

Granzyme

Answer 38

Protease entering cells via perforin pores to induce apoptosis

Question 39

Caspase-3

Answer 39

Executioner caspase activating apoptosis pathways in target cells