8.3 True or False: Self antigen recognition is needed in order to cross-link the pre-B-cell receptor, which in turn allows this complex to signal and permit the transition from pro-B cell to pre-B cell.
8.4 Matching: Match the B-cell stage with the proper description:
A. Early pro-B cell i.   V-DJ rearranging (heavy chain)
B. Small pre-B cell ii.  D-J rearranging (heavy chain)
C. Immature B cell iii. Expressing pre-B-cell receptor
D. Late pro-B cell iv. V-J rearranging (light chain)
E. Large pre-B cell v. Surface IgM 8.5 Short Answer: How does the process of allelic exclusion prevent the rearrangement of the second heavy-chain locus, and why is this important?
8.6 Short Answer: How can one large pre-B cell give rise to multiple B cells with different antigen specificities?
8.7 Matching: Match the following terms to the appropriate definition:
A. Receptor editing i. Result of persistent   autoreactivity after failure of   successful receptor editing
B. Isotypic exclusion ii. Selection of either the κ or the λ light chain
C. Clonal deletion iii. Result of a peripheral encounter of a weakly cross-linking or low-valence antigen
D. Anergy iv. Process by which the light-chain locus is rearranged in order to produce a nonautoreactive receptor
E. Immunological v.  B cells that have affinity for ignorance a self-antigen but for various  reasons do not respond to it 8.8 True or False: All CD4 and CD8 double-negative thymocytes are immature T cells.
8.9 Matching: Match the correct expression of CD44 and CD25 and the T-cell receptor locus rearrangement status with the appropriate DN T-cell stage:
A. DN1 i. CD44+CD25+, D to J TCRβ-chain   locus rearrangement
B. DN2 ii. CD44+CD25–, germline T-cell   receptor locus
C. DN3 iii. CD44lowCD25+, V to DJ β-chain  locus rearrangement
D. DN4 iv. CD44–CD25–, functional β-chain rearrangement 8.10 Fill-in-the-Blanks: Successful rearrangement of the ______ during the DN__ stage permits the formation of the pre-T-cell receptor, which is analogous in structure and function to the pre-B-cell receptor. The TCRβ chain associates itself with the _______, which allows ligand-independent cross-linking of the pre-T-cell receptor, causing __________, the arrest of further ________ gene rearrangement, and the expression of both _______. As with the B-cell light-chain locus, the _________ can undergo multiple rearrangements to produce a functional protein.
8.11 Matching: Match the following subsets of murine γ:δ T cells with the appropriate description:
A. Dendritic i.   Can be divided in two groups: epidermal IFN-γ and IL-4 producing, and IFN-γ T cells producing subsets
B. Vγ4+ ii.  Cells that home to the reproductive tract, lung, and dermis; upon  stimulation these can produce inflammatory cytokines
C. Vγ6+ T cells iii. A population of later developing γ:δ T cells programmed to secrete IL-17 when activated, and can be found in all lymphoid organs, as well as the dermis
D. Vγ1+ T cells iv. Cells that, as a response to a pathogen or a wound, can induce inflammation, promote wound healing, and produce growth factors; also characterized by their T-cell receptors’ use of the Vγ5 segment
E. Vγ7+ T cells v. Specifically home to the intestinal epithelium 8.12 Multiple Choice: Which of the following options correctly describes a difference between the B-cell receptor and the T-cell receptor?