Lecture 14: B Cell activation and Antibody Production Flashcards
Primary response differs from secondary response how
Secondary is - More rapid Larger amounts of Abs produced Isotype switching of heavy chain occurs Affinity maturation occurs
Antibody responses to what do not require Ag-specific helper T lymphocytes
Multivalent non-protein Ags with repeating epitopes, such as polysaccharides, some lipids, and nucleic acids
Antibody responses to what require CD4+ T cell help
Protein antigens
What facilitates the formation of germinal centers, and what happens in these centers
Follicular helper B cells
Activated B cells proliferate here
Follicular B-2 cells respond to
Protein Ags and thus initiate T-dependent Ab responses
Marginal zone B cells respond to
Multivalent Ags and are T independent
B-1 cells in mucosal sites respond to
Multivalent Ags and are T independent
B-1 B cells arise from where
Fetal liver
What guides the movement of Follicular B cells into the follicles of secondary lymph organs
CXCL13 chemokine secrected by resident follicular DCs
It attracts Naïve B cells to follicules
Soluble Ag fate in delivery to LN
Small Ags (Smaller than 70kD generally) may reach B cell zone of the follicle and interact directly with specific B cells
Large Ag fate in delivery to LN
May be captured by resident FDCs and transported into follicles where they can activate B cells
Microbe/Ag-Ab complex fate in delivery to LN
Captured by subcapsular sinus macrophages which deliver Ags to follicles
FDCs have unique capacity to retain
Immune Ag-Ab complexes on their surface for long periods (weeks to months)
Ag retention by FDCs is mediated by
FcyRIIB Fc receptors or CR1/CR2 (CD21) complement receptors
Follicular B cell survival depends on
Signals from BCR as well as inputs received from cytokine BAFF (B cell activating factor of the TNF family)