Immunology: Initiation of Acquired Immune Responses - B Cells Flashcards
where do
- B cells
- T cells
mature
- bone marrow
- thymus
what immune response are
- B cells
- T cells
responsible for
- humoral
- cellular
what is the role of B cells
- produce antibodies to attack pathogens in circulation
- defend against both EC and IC pathogens
what is the role of T cells
- defend against IC pathogens
what do CD4+ T cells do
- T helper cells
- regulate immune system
what do CD8+ T cells do
- cytotoxic T cells
- kill virally infected host cells
give a general description of antibodies
- bind to a specific antigen
- complex of 4 polypeptide chains
- unique variable region that binds to antigens (Fc)
how do B cells use antibodies
membrane bound antibodies - receptor to reg=cognise and bind to antigens
why is the B and T cell response more specific to antigens
they express 1 antigen receptors that binds to a specific antigen epitope
where are mature T and B cells usually
circulating between blood, lymph and 2* lymphoid tissue
how to T and B cells enter lymph nodes
via high endothelial venules (HEV)
what is the function of lymph nodes
- key site of pathogen detection
- faciliate T and B cell activation
what happens once
- B cells
- T cells
enter lymph nodes
- go to lymphoid follicle
- go to T cell area and interact with dendritic cells
how do denritic cells enter lymph nodes
via lymph
how do lymph and lymphocytes leave the lymph nodes and where to they go after
- leave through the medullary sinus then into lymph vessels
- eventually drains into a subclavian vein
what 2 types of cells do B cells differentiate into once activated
- plamsa B cells
- memory B cells
what is the role of plasma B cells
produce and secrete soluble antibodies
what is the role of memory B cells
long-lived and continually circulate after infection
what antibodies do B cells use to respond to specific antigens
membrane-bound Igd/IgG
describe how B cells encounter antigens
- soluble antigens are released into tissues as debris after phagocytosis
- they then travel to lymph nodes and are trapped by cells expressing opsonin receptors
- B cells encounter them and activate
what are opsonised antigens
antigens released into tissues after phagocytosis
what do B cells need to activate
- antigen
- ‘helping’ signal
what are the 2 signals B cells need to activate in
- protein antigens
- other antigens
- repetitive epitopes
- BCR binding and Th cell help
- BCR + antigen and PRRs + PAMPs
- multiple BCRs + antigens engaged
after actviation what happens to B cells
clonally proliferate forming a germinal centre, can then differentiate
