Immune System and Autoimmune Diseases

Questions and Answers

What is the term for the unresponsiveness of the immune system to an individual's own antigens?

Immunological tolerance

What is the result when tolerance to self-antigens is lost?

Autoimmune disease development

Why can't the immune system simply conceal self-antigens to maintain tolerance?

Because many self-antigens have ready access to the immune system

What is the primary mechanism responsible for the immune system's ability to discriminate between self and non-self antigens?

Immunological tolerance mechanisms Signup and view all the answers

What is a consequence of the immune system's ability to recognize self-antigens during lymphocyte maturation?

Generation of lymphocytes with self-antigen recognition ability Signup and view all the answers

What is an example of an autoimmune disease mentioned in the passage?

Lupus erythematosus Signup and view all the answers

What is the primary mechanism of eliminating self-reactive B cells during their development in the bone marrow?

Epitope recognition by BCRs Signup and view all the answers

Which of the following self-antigens are not present in the generative lymphoid organs and require peripheral tolerance mechanisms?

Self-antigens that arise during puberty Signup and view all the answers

What is the consequence of T cells binding to peptide-MHC complex during their development in the thymus?

Apoptotic death of T cells Signup and view all the answers

What is the primary function of central tolerance in the development of lymphocytes?

To eliminate autoreactive cells Signup and view all the answers

Which of the following is a limitation of central tolerance?

It is limited to the elimination of self-antigens present in the bone marrow and thymus Signup and view all the answers

What is the purpose of peripheral tolerance mechanisms?

To eliminate autoreactive cells that escape central tolerance Signup and view all the answers

Study Notes

Immunological Tolerance

Immunological tolerance is the ability of the immune system to not react against the individual's own (self) antigens.
Loss of tolerance to self-antigens leads to autoimmune diseases, such as lupus erythematosus and some forms of diabetes.

Mechanisms of Immunological Tolerance

Central tolerance: a mechanism that prevents immune responses to self-antigens present in the generative (central) lymphoid organs (bone marrow and thymus).
Peripheral tolerance: a mechanism that prevents immune responses to self-antigens present in peripheral (secondary) lymphoid organs or peripheral tissues.

Central Tolerance

Occurs during the early differentiation of B cells in the bone marrow and T cells in the thymus.
B cells that bind self-epitopes undergo apoptotic death (negative selection) in the bone marrow.
T cells that bind peptide-MHC complex undergo apoptotic death in the thymus.
This process removes many potentially autoreactive B and T cells before they enter the circulation.

Peripheral Tolerance

Additional mechanisms that control or eliminate autoreactive B and T cells after they exit the bone marrow or thymus.
Necessary to prevent autoreactive cells from inflicting damage on the body, especially for self-epitopes that arise after lymphogenesis (e.g., during puberty).