Immune System - Lecture 3 Part B Flashcards
What are Naive T cells stimulated by?
Antigen presenting cells in lymphoid organs
What happens once antigen T cells are stimulated by antigen presenting cells in lymphoid organs?
The T cells will differentiate into effector cells
What are the Effector T cells?
T Helper cells and T Cytotoxic cells
What are the two places that T cells are presented with antigens?
First in the lymphoid tissue then at the site of infection
How do T cells respond to their first encounter with an antigen?
By activating and proliferating and differentiating into effector cells
What are the different methods that CD4 and CD8 cells use to kill pathogens?
- CD4+ secrete cytokines that recruit and activate WBCs to kill the pathogen
- CD8+ lymphocytes kill the infected cells directly
Why is it expected to have many different types of T helper cells?
Because pathogens are very diverse it would be expected that we have many different T helper cells to respond to them
What do the different helper T cells secrete?
Different Cytokines
What are T helper I cells induced by?
Pathogens that are ingested by antigen presenting cells
How do T Helper I cells kill pathogens?
They release cytokines the stimulate phagocyte mediated killing of the ingested pathogen by macrophages
What cytokine is released by Helper T I cells?
Interferon gamma, the most potent macrophage activating cytokine
When are T helper II cells induced?
During parasitic worm infections
What do T helper II cells promote?
IgE production (an antibody)
What does the promotion of IgE production T helper II cells do?
Cause degranulation of mast cells and eosinophils to mediate the destruction of the parasite
Why do T Helper II cells cause degranulation through IgE production as opposed to stimulating phagocytosis?
Because parasites like worms are too large to ingest using macrophages
How do T helper II cells eliminate a worms?
They release cytokines that stimulate B cells to differentiate into plasma cells and produce IgE antibodies that coat the worms and serve as a binding source for mast cells and eosinophils
What do T helper II cells do in addition causing degranulation of mast cells and eosinophils?
They stimulate the production of mucus and intestinal peristalsis to eliminate killed worms from the body
When are T Helper 17 cells active?
During bacterial and fungal infections
How do Helper T 17 cells destroy extracellular pathogens?
They induce inflammatory reactions by secreting cytokines
What do the Cytokine released by T helper 17 cells do?
Stimulate the production of chemokines from other cells which recruit WBCs
What do T Helper cells do in addition to stimulating the production of chemokines?
They maintain the integrity of our epithelial barriers promoting repair of damaged epithelial cells and stimulating the production of endogenous microbial substances