Lecture 10: Host Defense II Flashcards
What activates the classical pathways of complement fixation
C1 binding to C-reactive protein on the pathogen surface
The classical complement pathways are activated by
- Ab binding to Ag
- C1 reactive protein binding
Initial complement component of classical pathway
C1q, C1r, C1s,C4, and C2
C3 convertase of classical and lectin
C4bC2b
C5 convertase of classical and lectin
C4bC2bC3b
Activator of the lectin pathway
Mannan binding lectin (MBL) and MBL-associated serine protease-2 (MASP-2)
Initial complement component of lectin pathway
C4, C2
Activator of alternative pathway
Contact of microbial cell wall with C3
Initial complement component of alternative pathway
C3, factor B, factor D, and properdin
C3 convertase in alternative pathway
C3bBb
C5 convertase in alternative pathway
C3bBbC3b
Biological consequences of complement activation
- Lysis
- Opsonization
- Activation of inflammatory response
- Clearance of immune complexes
Humoral immunity is mediated by
antibodies secreted by antigen-activated B cells and their progeny plasma cells
Antigens
- Induce specific, adaptive immune responses
2. React specifically with the products of the response
Paratropes
The part of an antibody which recognizes an antigen, the antigen-binding site of an antibody
A small region of the antibody’s Fab region
What have paratropes with a specificity for a single antigenic epitope
Abs, BCR and TCR
What recognizes native protein antigens
B-cell receptors
TCRs recognize
processed Ag on MHC
BCRs and Abs recognize
native Ag without processing or MHC
Adaptive immunity
Adaptive, specific immune responses that are induced by exposure to an antigen(s), the response is specific for the inducing antigen(s), and immunologic memory is generated
Primary versus secondary humoral immune response
Secondary has a shorter lag phase, greater magnitude, and class-switched IgG
