Exam 7: The Development of T Lymphocytes

The human thymus begins to degenerate as early as one year after birth.This process is called ______ and is marked by the accumulation of ___ once occupied by thymocytes.

Which of the following statements about Notch 1 is correct? (Select all that apply.)

As we age,our thymus shrinks,or atrophies,by a process called involution,yet T-cell immunity is still functional in old age. A.Explain how T-cell numbers in the periphery remain constant in the absence of continual replenishment from the thymus. B.How does this differ from the maintenance of the B-cell repertoire?

Once a thymocyte has productively rearranged a β-chain gene,which of these event(s)can occur subsequently? (Select all that apply.)

After interaction with thymic stromal cells,_____,a glycoprotein not expressed by the uncommitted progenitor cell is activated in developing thymocytes.(Select all that apply.)

Mature B cells undergo somatic hypermutation after activation,which,after affinity maturation,results in the production of antibody with a higher affinity for antigen than in the primary antibody response.Suggest some reasons why T cells have not evolved the same capacity.

_____ is a T-cell-specific adhesion molecule expressed before the expression of a functional T-cell receptor while the thymocytes are still in their double-negative stage of development.

Healthy individuals have approximately ____ of CD4 T cells compared with CD8 T cells.

The function of negative selection of thymocytes in the thymus is to eliminate

Double-negative thymocytes initiate rearrangement at the _____ locus (loci)before all other T-cell receptor genes.

Which of the following is the first T-cell receptor complex containing the β chain to reach the cell surface during the development of T lymphocytes?

A.What is immunological tolerance? B.What is the general name for the antigens against which the immune system is normally tolerant?

There are many parallels between the development of B cells and T cells.Identify the incorrectly matched counterpart in B cells (left)versus T cells (right).

_______ of thymocytes is necessary to produce a T-cell repertoire capable of interacting with self-MHC molecules.

Which of the following statements are true of a T cell that expresses two α chains (and thus two different T-cell receptors)as a result of ineffective allelic exclusion of the α chain during rearrangement? (Select all that apply.)

All of the following types of protein are processed and presented by macrophages in the thymus except _____ proteins.

A.Explain two ways in which the expression and processing of self antigens in thymic epithelium differs from the expression and processing of self antigens outside the thymus. B.In what way is the thymic situation advantageous for the purposes of negative selection?

The surrogate light chain operating during pre-B-cell development is made up of VpreB:λ.Its expression with μ on the pre-B-cell surface is an important checkpoint in B-cell maturation.Name the T-cell analog of VpreB:λ5 and discuss how it is functionally similar.

Which of the following processes is not dependent on an interaction involving MHC class I or class II molecules? (Select all that apply.)