Immunology 8: Self Tolerance

Question 1

Self tolerance

Answer 1

mechanism to ensure precursor cells specific for self-antigens are not induced
→ there must be property of self antigens to distinguish them from foreign antigens and that immune systems utilizes this property to avoid self reactivity

Question 2

Suggested model for achieving self tolerance

Answer 2

Self-antigens distinguished form foreign antigens because of early and continuous presence
→ receptor-bearing precursor cells arise from stem cells w/o this receptor. If precursor cell interacts with antigen when it first expresses a receptor, will cause death
→ if a self-antigen is present before any of these precursor cells arise, wouldn’t respond to it – when a cell then interacts with it, would multiply and its descendants differentiate

Question 3

This suggested model explained what?

Answer 3

→ why exposure to foreign antigens during development resulted in immune system regarding antigen as self and that immune system would contain now precursor cells specific for such antigen, so there would be no immune response against antigen

Question 4

Evidence for this model within last few years?

Answer 4

→ Shown that T cells specific for self-antigens initially generated in thymus, but then most of them disappear due to presence of self-antigen

Question 5

Model accounts for?

Answer 5

→ fact that attempts to find helper T cells for most self-antigens in healthy animals/people are unsuccessful
→ makes sense, since T cells needed to generate antibody response, don’t want them there to induce antibody against self

Question 6

A self-antigen can interact with receptors of a ____.

Answer 6

B cell, in absense of helper T cells
→ interaction doesn’t result in activation of B cell, but does cause death of B cell
→ so not only does absence of helper T cells result in no antibody response, also ensures that anti-self B cells are eliminated

Question 7

Elimination of anti self B cells called?

Answer 7

Antigen-specific inactivation