Lymphatic Stuff Flashcards
Peripheral vs. Central Lymphoid Tissues
Peripheral tissues where you find adult, immunologically active lymphocytes, basically anything except bone marrow/thymus
Lymph Node 3 Zones (& 7 contents)
Cortex - B lcytes, primary and secondary follicles
Paracortex - T lymphocytes
Medulla - B&T Lymphocytes, Macrophages, and Plasma Cells
Main Point about Lymphocyte Organization in Lymphoid Tissues
Lymphocytes organized in lymphoid tissues in such a way to most efficiently/effectively active immune response
Recirculation of Lymphocytes (2)
Effector lymphocytes circulate through peripheral lymphoid tissues for best chance to encounter an antigen and initiate immune response
Memory cells & Ag presenting cells can continue circulating, monitoring and activating immune responses
Antigenic Determinant/Epitope
Small part of molecule (like small AA sequence) that the lymphocyte R actually binds on the Ag
Hapten (3)
Ag that can’t produce immune response unless tightly associated w/ an immunogen
- T helper cells recognize antigenic regions on rest of Hepten-containing molecule and activate the Hapten-bound B Cell
- So B cells often need to bind Ag AND receive signaling from Ts binding to rest of pathogen to activate, so Ag determinants need to be bound to pathogen to have effect
6 Factors Influencing Immunogenicity
Foreigness - higher number of antigenic differences, more immunogenic
Size - larger = more antigenic determinants
Chemical Composition - Sequence determinants from primary structure and conformational determinants from higher structure levels
Dose
Route
Adjuvant - can contain immunogen to site of infection & act as irritant to draw immune response
Difference b/w Linear and Discontinuous Epitope
Linear just primary sequence different, so can be recognized on chewed up prot
Discontinuous from folding giving close proximity of Agic residues, so protein must be intact
Chemical Difference b/w Antigens Recognized by Bs and Ts
Bs - pretty much anything, artificial or natural
Ts - almost always proteins
Molecular Location Difference b/w Ab and T Cell R Epitopes
Abs bind outside regions of molecule in conformational shape
Ts recognize linear sequences inside the molecule, which will be chewed up and expressed on host cell surface MHC
Toxins
Often superantigens
Difference b/w TI (T-Independent) and TD (T-Dependent) Antigens
TI - like flagella, long stretch of identical repeating epitopes that can activate a ton of Igs on a single B cell, which can cause cross-linking of Rs which activates B cell
TD - more common, a lot of unique antigenic determinants singly placed so require a T cell to activate B cells
