Immunology Lecture 11. Flashcards
What is tolerance?
lack of response to a specific antigen
What can tolerance involve?
elimination, neutralization, generation of unique cell populations
Why is tolerance important?
potential for auto reactivity with induce rearrangements in V regions of T and B cells - failure for tolerance makes autoimmune diseases
What type of cell expresses AIRE?
medullary epithelial cell in the thymus
What are the two major mechanisms of tolerance induction?
deletion or reactive cells or ANERGY
What does lack of second signal cause? What is the second signal in T cells?
ANERGY CD28/B7
What are T regulatory cell markers?
FOXP3+, CD25+, CD4
TGF-B
induces T regulatory cells
IL-10
produce immune dampening
IPEX
the result of no FOXP3 = enteropathy, diabetes, thyroiditis, dermatitis
Why are tumor cells not killed by the immune system?
cancer cells produce TGF-B which induce T regulatory cells, T regulatory cells release IL-10, no stimulation of cytotoxic T cells happens, so T cell is not killed
How are B cells activated by T cells?
CD40/CD40L and cytokines
Why is T helper response for B cells important?
no AIRE expressed in bone marrow - more likely to respond to self
What does no germinal centers in lymph nodes suggest?
no t cell help for b cells
How does dose induce/maintain tolerance?
a higher or lower does outside the range of immunological response induces tolerance
