Antibodies and Complements Flashcards
T/F. If antigen A is similar to antigen B, the body can distinguish between them and initiate separate immune responses.
True.
What are some important features of antibodies?
Bind a variety of antigenic structures.
Exquisite discrimination of similar antigens.
Bind antigen with great strength.
Recognize antigen in its native form.
The overall mission of antibodies is to neutralize the target ___.
antigen
Which process uses antibodies to tag microbial organisms or infected cells for phagocytosis?
opsonization
___ ___ is the recruit complement system to destroy microbial organisms or infected cells.
Complement Fixation
___ ___ binds toxins in the blood and tissue to facilitate the removal of the toxins.
Direct neutralization
T/F. Opsonization prevents bacterial adherence.
False, neutralization uses antibodies to prevent bacterial adherence. Opsonization has antibodies that promote phagocytosis.
What is the major immunoglobulin in serum?
IgG (70-75% of all Igs)
Which Ig represents the basic structure of all Igs?
IgG
T/F. IgD provides neonatal immunity and plays a role in immunological memory.
False, IgG provides neonatal immunity and plays a role in immunological memory.
IgD is less than ___% of circulating Igs, is a major component of ___ cell surface Ig, and is also called a ___-cell receptor.
1; B; B
Which immunoglobulin is very scarce in serum and found on the surface of basophils and mast cells?
IgE
___ is important for killing large parasites and contributes to an allergic reaction.
IgE
___ mast cells have preformed granules containing ___ and other inflammatory mediators. Multivalent antigen ___ IgE antibody bound at the mast-cell surface, causing the release of granule contents.
Resting; histamine; crosslinks
Which immunoglobulin is secreted into saliva?
IgA
T/F. IgA is usually assembled as a dimer and its receptor binds it to the mucosal epithelium.
False, IgA is a dimer but its receptor transports it across the mucosal epithelium.
Which immunoglobulin is a pentamer and makes up 10% of the total Igs?
IgM
What two immunoglobulins can serve as B cell receptors?
IgD and IgM
T/F. IgM is the first secreted Ab in response to the initial antigenic challenge.
True.
What defense systems in the body does complement contribute to?
Control inflammatory reactions Chemotaxis Clearance of immune complexes Cellular activation Antimicrobial defense
Which complement family member is a central component?
C3
Which complement family members are late components?
C5
C6,C7, C8
C9
Many complement components are ___. Their active sites are masked.
Activation occurs when the masking is removed mostly by ___ ___, resulting in the exposure of the active site.
proenzymes; proteolytic cleavage
T/F. Fragments of complement molecules are the active complements.
True.
What are the principle functions of the complement system?
opsonization and cell activation
chemotaxis
lysis of target cells
Explain the process of opsonization and cell activation.
Complement fragments coat the surface of a target. Immune cells bind to coated target. Phagocytosis and cell activation.
During chemotaxis, small ___ of complement form a ___ ___ that stimulates immune cells to move towards the site of infection.
fragments; concentration gradient
Complement activation results in the assembly of ___ ___ ___. It insert itself into lipid bilayers and makes a large hole on the cell membrane to cause cell lysis.
membrane attack complex (MAC)
The generation of active complement ___ leads to the expression of complement ___ (CR) on phagocytic cells.
fragments; receptors
Microbial surface stimulate the activation of complements.
While ___ and ___ coat the surface of target, ___ and ___ induce chemotaxis. Recruited leukocytes kill the invading microbes.
C3b; C4b; C3a; C5a
Binding of C3b to the microbe causes activation of ___ (a late component of complement). This leads to the formation of the ___ ___ ___, which causes lysis of the microbe.
C5b; membrane attack complex
T/F. The classical pathway is similar to the innate immune response and the alternative pathway is similar to the adaptive immune response.
False, classical is adaptive because it is activated by an antibody-antigen complex containing IgM or IgG1-3.
The alternative pathway is innate because it is activated directly by microbial cell walls.
What two pathways are activated by microbial surfaces?
lectin and alternative pathways
What does the lectin pathway recognize?
terminal mannose groups
___ (C3a/C3b) binds factor ___ (H/I) on self surface and is ___ (activated/deactivated) by factor ___ (H/I).
C3b; H; deactivated; I
C3b is deactived by ___ in fluid.
hydrolysis
C3b binds factor ___(B/D) on the surface of microbes and it becomes ___.
B; C3bB
C3bB is cleaved by factor ___ (B/D) to generate C3bBb. C3bBb is the ___ pathway’s C3 ___.
D; alternative; convertase
T/F. C3bBb catalyzes a significant amount of C3 cleavage.
True
What is the adapter for the classical pathway?
C1
what makes up the C1 complex?
C1q and C1r2s2
T/F. Free antibody engages C1.
False, only antibody bound IgM or IgG to tissues activates C1 to generate C1qr2s2.
Activated C1 cleave ___ and ___ to form C4b2a. C4b2a is the classical ___ ___. C4b2a3b is the classical ___ ___.
C2; C4; C3 convertase; C5 convertase
Matching:
- Phagocytosis of opsonized particles
- Activation of late steps of complement
- Inflammation induced by breakdown products
A. C5 convertase
B. C3b
C. C5a, C3a, C4a
- B
- A
- C
The late stage activation of complement forms the ___ ___ ___.
membrane attack complex.
What is required to initiate MAC formation?
C5b
T/F. C6, C7, C8, and multiple C9 form MAC.
False, C5b, C6, C7, C8, and multiple C9 form MAC.
