Term
| T/F T cells are dissimilar to B cells in that they have more than 1 terminally differentiated type of cell. |
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Definition
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Term
| T/F The thymus directly recieves T cells via lymph and blood vessels. |
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Definition
| FALSE, the thymus does not recieve lymph |
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Term
| The thymic stroma consists of... |
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Definition
| thymocytes embedded in a network of epithelial cells |
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Term
| What part of the thymus is derived from ectoderm? endoderm? |
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Definition
| ectoderm= thymic cortex; endoderm= thymic medulla |
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Term
| When in your life span does the thymus begin to degenerate? |
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Definition
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Term
| What cell types can be found in the thymic cortex? |
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Definition
| immature thymocytes and cortical epithelial cells |
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Term
| What cell types can be found in the thymic medulla? |
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Definition
| mature thymocytes, dendritic cells, macrophages, and medulary epithelial cells |
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Term
| Thymocytes that undergo apoptosis in the thymic medulla are "cleaned" up by... |
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Definition
| macrophages in structures called hassall's corpuscles |
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Term
| What T cell ancestor first enters the thymus? |
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Definition
| the progenitor cell (CD34) |
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Term
| T/F IL-7 is necessary for T cell development. |
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Definition
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Term
| What is a double negative thymocyte? |
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Definition
| thymocyte without CD4 or CD8 |
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Term
| What is the function of notch 1? |
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Definition
| Notch 1 is a receptor on the T cell which binds a ligand on the thymic epithelium. The intracellular domain of Notch1 is cleaved off and goes to the nucleus to activate T cell specific transcription factors |
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Term
| How does a double negative T cell become a gamma delta T cell? |
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Definition
| Gamma and delta chain genes rearrange. A gamma:delta receptor assembles. Signals through gamma:delta TCR stop further rearrangments and cell is commited to being gamma delta |
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Term
| What happens if a beta chain rearranges in a double negative T cell? |
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Definition
| a pre TCR assembles and tells cell to stop rearranging and instead express CD4 and CD8 |
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Term
| T/F Surrogate light chains are used in B cell development but not T cell development. |
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Definition
| FALSE. they bind to u in B cells and beta in T cells |
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Term
| What makes up the pre-T cell receptor? |
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Definition
| rearranged beta with surrogate light chain, CD3 complex and zeta chain |
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Term
| The pre-T cell reinitiates rearrangment of ___, ___, and ___. |
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Definition
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Term
| What is the structural difference between a pre-T cell receptor and a T cell receptor? |
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Definition
| pre T cell receptor has a pT"alpha" while T cell receptor has an "alpha" chain |
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Term
| What happens to the delta chain when the alpha chain is successfully rearranged? |
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Definition
| it is deleted because the delta locus is embedded in the alpha locus |
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Term
| How does the pre T cell know if the alpha rearrangement has been successful? |
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Definition
| translocates alpha chain to ER and test assembly with beta chain |
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Term
| T/F pT"alpha" is constitutively expressed throughout T cell development |
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Definition
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Term
| What is receptor editing? |
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Definition
| when the TcR doesn't bind a peptide:MHC complex within 3-4 days and ends up undergoing further chain rearrangements which improves its chance for positive selection |
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Term
| What does it mean when you say T cells are MHC restricted? |
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Definition
| they only recognize the peptide antigen in the context of that MHC molecule which it bound |
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Term
| What characterizes MHC class II defieciency? What is the tx? |
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Definition
| low lymphocytes, low B cells, normal CD8, no CD4 cells, no immunoglobulin, bone marrow transplant but you have to immunosuppress |
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Term
| What happens to autoreactive T cellsin the thymus? |
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Definition
| they are bound by thymal dendritic cells in the medulla and die |
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Term
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Definition
| a transcription factor that tells epithelial cells of the thymus to make low levels of tissue specific genes for negative slection |
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Term
| What cells in the thymus mediate positive selection? negative? |
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Definition
| epithelial; mostly dendritic cells but also thymocytes and macrophages |
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Term
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Definition
| Autoimmune polyendocrinopathy candidiasis. When there is a defect in AIRE and T cells are released from the thymus that recognize some self tissue |
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Term
| T/F Only B cells can undergo anergy. |
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Definition
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Term
| How do regulatory T cells prevent autoimmune disease? |
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Definition
| they recognize self antigens but when they bind self antigen:MHC II complexes they suppress the proliferation of CD4 T cells that have bound to the same antigen presenting cell |
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Term
| What's a normal CD4:CD8 ratio? |
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Definition
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Term
| T/F Intermediate T cell stages most often cause T cell tumors. |
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Definition
| False. T cell tumors are more often caused by earlier or later stages |
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Term
| Characteristics of T cell lymphoma |
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Definition
| high eosinophils and high IgE |
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Term
| Why do you treat T cell lymphoma with prednisone? |
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Definition
| inhibit NFkB transcription by inducing IkG which inhibits pro inflammatory cytokine expression |
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