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Revision of T-cell differentiation node #2375

Closed gocentral closed 9 years ago

gocentral commented 19 years ago

Revision of T-cell differentiation node

T-cell differentiation is a complicated matter, and its current representation in the GO is faulty. Following my review of the topic, I am proposing to rearrange some terms, add some new ones, and add or change certain definitions.

Comments are welcome. Note that the source file has been uploaded as well.

-- Alex

Current ontological relationships in T-cell differentiation and T-cell activation. Hidden child terms are indicated with a '+'.

lymphocyte differentiation ; GO:0030098 --% B-cell differentiation ; GO:0030183 + --< regulation of lymphocyte differentiation ; GO:0045619 + --% T-cell differentiation ; GO:0030217 ----% alpha-beta T-cell differentiation ; GO:0046632 ------< regulation of alpha-beta T-cell differentiation ; GO:0046637 --------% negative regulation of alpha-beta T-cell differentiation ; GO:0046639 --------% positive regulation of alpha-beta T-cell differentiation ; GO:0046638 ----% cytotoxic T-cell differentiation ; GO:0045065 + ----% gamma-delta T-cell differentiation ; GO:0042492 + ----% NK T-cell differentiation ; GO:0001865 + ----< regulation of T-cell differentiation ; GO:0045580 + ----% regulatory T-cell differentiation ; GO:0045066 + ----% T-helper cell differentiation ; GO:0042093 ------< regulation of T-helper cell differentiation ; GO:0045622 --------% negative regulation of T-helper cell differentiation ; GO:0045623 + --------% positive regulation of T-helper cell differentiation ; GO:0045624 + --------% regulation of T-helper 1 cell differentiation ; GO:0045625 + --------% regulation of T-helper 2 cell differentiation ; GO:0045628 + --% T-cell selection ; GO:0045058 [currently undefined] ----% extrathymic T-cell selection ; GO:0045062 [currently undefined] ------% negative extrathymic T-cell selection ; GO:0045068 [currently undefined] ------% positive extrathymic T-cell selection ; GO:0045067 [currently undefined] ----% thymic T-cell selection ; GO:0045061 [currently undefined] ------% negative thymic T-cell selection ; GO:0045060 [currently undefined] ------% positive thymic T-cell selection ; GO:0045059 [currently undefined] --% thymocyte differentiation ; GO:0046652

Proposed correction of ontological relationships in T-cell differentiation. Please note changes in parentage for particular terms which are not noted elsewhere.

lymphocyte differentiation ; GO:0030098 --% B-cell differentiation ; GO:0030183 + --< regulation of lymphocyte differentiation ; GO:0045619 + --% T-cell differentiation ; GO:0030217 ----% alpha-beta T-cell differentiation ; GO:0046632 ------< beta-selection ; GO:NewTerm ------< regulation of alpha-beta T-cell differentiation ; GO:0046637 --------% negative regulation of alpha-beta T-cell differentiation ; GO:0046639 --------% positive regulation of alpha-beta T-cell differentiation ; GO:0046638 ----% CD4-positive T-cell differentiation ; GO:NewTerm ------< CD4-positive T-cell lineage commitment ; GO:NewTerm ------< regulation of CD4-positive T-cell differentiation ; GO:NewTerm --------% negative regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + --------% positive regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + --------% regulation of T-helper cell differentiation ; GO:0045622 ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + ----------% regulation of T-helper 1 cell differentiation ; GO:0045625 + ----------% regulation of T-helper 2 cell differentiation ; GO:0045628 + ------% T-helper cell differentiation ; GO:0042093 [note new parentage] --------< regulation of T-helper cell differentiation ; GO:0045622 ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + ----------% regulation of T-helper 1 cell differentiation ; GO:0045625 + ----------% regulation of T-helper 2 cell differentiation ; GO:0045628 + ----% CD8-positive T-cell differentiation ; GO:NewTerm ------< CD8-positive T-cell lineage commitment ; GO:NewTerm ------< regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% negative regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% positive regulation of CD8-positive T-cell differentiation ; GO:NewTerm ----% cytotoxic T-cell differentiation ; GO:0045065 ------< regulation of cytotoxic T-cell differentiation ; GO:0045583 --------% negative regulation of cytotoxic T-cell differentiation ; GO:0045584 --------% positive regulation of cytotoxic T-cell differentiation ; GO:0045585 ----% gamma-delta T-cell differentiation ; GO:0042492 ------< regulation of gamma-delta T-cell differentiation ; GO:0045586 --------% negative regulation of gamma-delta T-cell differentiation ; GO:0045587 --------% positive regulation of gamma-delta T-cell differentiation ; GO:0045588 ----% memory T-cell differentiation ; GO:NewTerm ------< regulation of memory T-cell differentiation ; GO:NewTerm --------% negative regulation of memory T-cell differentiation ; GO:NewTerm --------% positive regulation of memory T-cell differentiation ; GO:NewTerm ----% NK T-cell differentiation ; GO:0001865 ------< regulation of NK T-cell differentiation ; GO:0051136 --------% negative regulation of NK T-cell differentiation ; GO:0051137 --------% positive regulation of NK T-cell differentiation ; GO:0051138 ----< regulation of T-cell differentiation ; GO:0045580 ------% negative regulation of T-cell differentiation ; GO:0045581 --------% negative regulation of alpha-beta T-cell differentiation ; GO:0046639 --------% negative regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + [note revised parentage] --------% negative regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% negative regulation of cytotoxic T-cell differentiation ; GO:0045584 --------% negative regulation of gamma-delta T-cell differentiation ; GO:0045587 --------% negative regulation of memory T-cell differentiation ; GO:NewTerm --------% negative regulation of NK T-cell differentiation ; GO:0051137 --------% negative regulation of regulatory T-cell differentiation ; GO:0045590 ------% positive regulation of T-cell differentiation ; GO:0045582 --------% positive regulation of alpha-beta T-cell differentiation ; GO:0046638 --------% positive regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + [note revised parentage] --------% positive regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% positive regulation of cytotoxic T-cell differentiation ; GO:0045585 --------% positive regulation of gamma-delta T-cell differentiation ; GO:0045588 --------% positive regulation of memory T-cell differentiation ; GO:NewTerm --------% positive regulation of NK T-cell differentiation ; GO:0051138 --------% positive regulation of regulatory T-cell differentiation ; GO:0045591 ------% regulation of alpha-beta T-cell differentiation ; GO:0046637 --------% negative regulation of alpha-beta T-cell differentiation ; GO:0046639 --------% positive regulation of alpha-beta T-cell differentiation ; GO:0046638 ------% regulation of CD4-positive T-cell differentiation ; GO:NewTerm --------% negative regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + --------% positive regulation of CD4-positive T-cell differentiation ; GO:NewTerm ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + --------% regulation of T-helper cell differentiation ; GO:0045622 [note revised parentage] ----------% negative regulation of T-helper cell differentiation ; GO:0045623 + ----------% positive regulation of T-helper cell differentiation ; GO:0045624 + ----------% regulation of T-helper 1 cell differentiation ; GO:0045625 + ----------% regulation of T-helper 2 cell differentiation ; GO:0045628 + ------% regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% negative regulation of CD8-positive T-cell differentiation ; GO:NewTerm --------% positive regulation of CD8-positive T-cell differentiation ; GO:NewTerm ------% regulation of cytotoxic T-cell differentiation ; GO:0045583 --------% negative regulation of cytotoxic T-cell differentiation ; GO:0045584 --------% positive regulation of cytotoxic T-cell differentiation ; GO:0045585 ------% regulation of gamma-delta T-cell differentiation ; GO:0045586 --------% negative regulation of gamma-delta T-cell differentiation ; GO:0045587 --------% positive regulation of gamma-delta T-cell differentiation ; GO:0045588 ------% regulation of memory T-cell differentiation ; GO:NewTerm --------% negative regulation of memory T-cell differentiation ; GO:NewTerm --------% positive regulation of memory T-cell differentiation ; GO:NewTerm ------% regulation of NK T-cell differentiation ; GO:0051136 --------% negative regulation of NK T-cell differentiation ; GO:0051137 --------% positive regulation of NK T-cell differentiation ; GO:0051138 ------% regulation of regulatory T-cell differentiation ; GO:0045589 --------% negative regulation of regulatory T-cell differentiation ; GO:0045590 --------% positive regulation of regulatory T-cell differentiation ; GO:0045591 ----% regulatory T-cell differentiation ; GO:0045066 ------< regulation of regulatory T-cell differentiation ; GO:0045589 --------% negative regulation of regulatory T-cell differentiation ; GO:0045590 --------% positive regulation of regulatory T-cell differentiation ; GO:0045591 ----< T-cell selection ; GO:0045058 [note revised parentage] ------% extrathymic T-cell selection ; GO:0045062 --------% negative extrathymic T-cell selection ; GO:0045068 --------% positive extrathymic T-cell selection ; GO:0045067 ------% thymic T-cell selection ; GO:0045061 --------% negative thymic T-cell selection ; GO:0045060 --------% positive thymic T-cell selection ; GO:0045059 ------% negative T-cell selection ; GO:NewTerm --------% negative extrathymic T-cell selection ; GO:0045068 [note new parent here] --------% negative thymic T-cell selection ; GO:0045060 [note new parent here] ------% positive T-cell selection ; GO:NewTerm --------< CD4-positive/CD8-positive T-cell lineage commitment ; GO:NewTerm ----------% CD4 lineage commitment ; GO:NewTerm ----------% CD8 lineage commitment ; GO:NewTerm --------% positive extrathymic T-cell selection ; GO:0045067 [note new parent here] --------% positive thymic T-cell selection ; GO:0045059 [note new parent here] ------% beta-selection ; GO:NewTerm

New Terms 1) Term Name: beta selection

Definition: The signaling from the pre-T-cell receptor complex indicative of successful recombination of a T-cell receptor beta chain into a translatable protein coding sequence and the resulting processes which lead to the rescue from apoptosis and subsequent proliferation of an immature T-cell.

Parentage: part-of to GO:0046632 alpha-beta T-cell differentiation, is-a to GO:0045058 T-cell selection.

Reference: ISBN:0781735149, PMID:12220932

2) Term Name: CD4-positive T-cell differentiation

Definition: The process whereby a relatively unspecialized T- cell acquires specialized features of a mature CD4-positive T-cell.

Parentage: is-a to GO:0030217 T-cell differentiation.

Reference: ISBN:0781735149

Editorial Note: Although this term and GO:0042093 T-helper cell differentiation may be thought to overlap in meaning by some perspectives, the terms helper T-cell and CD4-positive T cells are not strictly synonymous. The meaning of T cell help is originally the help provided to B cells by T-cells in the form of cytokines to promote antibody production, and this meaning was later expanded to include help provided indirectly to CD8-positive T-cells to promote their effector functions. However T cells fall into a wide variety of partially overlapping subsets based on surface marker expression, cytokine production, and cytotoxic potential and CD4+ T cells do not strictly provide help in all instances, nor are they the only T cell type capable of producing help in the form of particular cytokines that promote antibody responses. A prime example of CD4-positive T cells which are not helper T cells is CD4+CD25+ subset, which are regulatory T cells, but do not provide help to B cells. The point in providing terms with overlapping meaning in the GO is to allow annotators to select the best terms or combinations of terms to describe the experimental data concerning particular gene products.
Because the expression of CD4 and CD8 on non-overlapping sets of T cells is so basic to T cell biology, both in terms of activation pathways via binding MHC Class II or Class I molecules, respectively, and in terms of broad programs of gene expression, I believe it is important for the GO to provide these terms.

3) Term Name: CD4-positive T-cell lineage commitment

Synonym: CD4-positive T-cell cell fate commitment

Definition: The process be which an immature T-cell becomes committed to becoming a CD4-positive T-cell.

Parentage: part-of to GO:NewTerm CD4-positive T-cell differentiation, is-a to GO:NewTerm CD4-positive/CD8- positive T-cell lineage commitment

Reference: ISBN:0781735149

4) Term Name: regulation of CD4-positive T-cell differentiation

Definition: Any process that modulates the frequency, rate, or extent of CD4-positive T-cell differentiation

Parentage: part-of to GO:NewTerm CD4-positive T-cell differentiation

Reference: ISBN:0781735149

5) Term Name: negative regulation of CD4-positive T-cell differentiation

Definition: Any process that stops, prevents, or reduces the rate of CD4-positive T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of CD4-positive T-cell differentiation

Reference: ISBN:0781735149

6) Term Name: positive regulation of CD4-positive T-cell differentiation

Definition: Any process that activates or increases the rate of CD4-positive T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of CD4-positive T-cell differentiation

Reference: ISBN:0781735149

7) Term Name: CD8-positive T-cell differentiation

Definition: The process whereby a relatively unspecialized T- cell acquires specialized features of a mature CD8-positive T-cell.

Parentage: is-a to GO:0030217 T-cell differentiation.

Reference: ISBN:0781735149

Editorial Note: Although this term and GO:0045065 cytotoxic T-cell differentiation may be thought to overlap in meaning by some perspectives, the two terms are not at all synonymous.
Cytoxicity is a well documented feature of CD4+ T-cells both in vitro and in vivo, as well as a feature of CD4-CD8- gamma- delta T-cells. Although the signaling pathways in these cell types are not entirely identical, the effector pathways of granule exocytosis or Fas ligand-fas interactions are shared and suggest common transcriptional programs in cells that express cytotoxic potential. CD8 positive T-cells commonly demonstrate cytotoxicity, but also have other important activities, such as cytokine production, and subsets of non- cytotoxic CD8 cells have been demonstrated as well.

8) Term Name: CD8-positive T-cell lineage commitment

Synonym: CD8-positive T-cell cell fate commitment

Definition: The process be which an immature T-cell becomes committed to becoming a CD8-positive T-cell.

Parentage: part-of to GO:NewTerm CD4-positive T-cell differentiation, is-a to GO:NewTerm CD4-positive/CD8- positive T-cell lineage commitment

Reference: ISBN:0781735149

9) Term Name: regulation of CD8-positive T-cell differentiation

Definition: Any process that modulates the frequency, rate, or extent of CD8-positive T-cell differentiation

Parentage: part-of to GO:NewTerm CD8-positive T-cell differentiation

Reference: ISBN:0781735149

10) Term Name: negative regulation of CD8-positive T-cell differentiation

Definition: Any process that stops, prevents, or reduces the rate of CD8-positive T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of CD8-positive T-cell differentiation

Reference: ISBN:0781735149

11) Term Name: positive regulation of CD8-positive T-cell differentiation

Definition: Any process that activates or increases the rate of CD8-positive T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of CD8-positive T-cell differentiation

Reference: ISBN:0781735149

12) Term Name: memory T-cell differentiation

Definition: The process whereby a newly activated T-cell acquires specialized features of a memory T-cell.

Parentage: is-a to GO:0030217 T-cell differentiation.

Reference: ISBN:0781735149

Editorial Note: Memory T-cells have a distinct phenotype both in terms of surface marker expression and in life-span.

13) Term Name: regulation of memory T-cell differentiation

Definition: Any process that modulates the frequency, rate, or extent of memory T-cell differentiation

Parentage: part-of to GO:NewTerm memory T-cell differentiation

Reference: ISBN:0781735149

14) Term Name: negative regulation of memory T-cell differentiation

Definition: Any process that stops, prevents, or reduces the rate of memory T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of memory T-cell differentiation

Reference: ISBN:0781735149

15) Term Name: positive regulation of memory T-cell differentiation

Definition: Any process that activates or increases the rate of memory T-cell differentiation

Parentage: is-a to GO:NewTerm regulation of memory T-cell differentiation

Reference: ISBN:0781735149

16) Term Name: negative T-cell selection

Definition: The process of elimination of immature T-cells which react strongly with self-antigens.

Parentage: is-a to GO:0045058 T-cell selection

Reference: ISBN:0781735149, PMID:12414722

17) Term Name: positive T-cell selection

Definition: The process of sparing immature T-cells which react with self-MHC protein complexes with low affinity levels from apoptotic death.

Parentage: is-a to GO:0045058 T-cell selection

Reference: ISBN:0781735149, PMID:12414722

Editorial Note: The "low affinity levels" is key to positive selection; this is not an error in the formulation of the definition.

18) Term Name: CD4-positive/CD8-positive T-cell lineage commitment

Definition: The process by which an immature T-cell commits to CD4-positive T-cell lineage or the CD8-positive lineage.

Parentage: is-a to GO:0045165 cell fate commitment, part-of to GO:NewTerm "positive T-cell selection" below.

Reference: ISBN:0781735149

19) Term Name: pre-T-cell receptor complex

Definition: A receptor complex found on immature T-cells consisting of a T-cell receptor beta chain and the pre-TCR- alpha chain, along with additional signaling components including CD3 family members and additional signaling proteins.

Parentage: is-a to GO:0043235 receptor complex

Reference: ISBN:0781735149, PMID:12220932

New Definitions

20) T-cell selection ; GO:0045058

Currently undefined

Proposed definition: The processes through which T-cells that express T-cell receptors which are restricted by self MHC protein complexes and tolerant to self antigens are selected for further maturation.

Reference: ISBN:0781735149, PMID: 12414722

21) extrathymic T-cell selection ; GO:0045062

Currently undefined

Proposed definition: Processes of T-cell selection that occur in extrathymic locations, often resulting T-cells of distinct specificities from those selected in the thymus.

Reference: ISBN:0781735149, PMID:7880383

22) negative extrathymic T-cell selection ; GO:0045068

Currently undefined

Proposed definition: The process of elimination of extrathymically maturing T-cells which react strongly with self-antigens.

Reference: ISBN:0781735149, PMID:7880383

23) positive extrathymic T-cell selection ; GO:0045067

Currently undefined

Proposed definition: The process of sparing extrathymically maturing T-cells which react with self-MHC protein complexes with low affinity levels from apoptotic death.

Reference: ISBN:0781735149, PMID:7880383

24) thymic T-cell selection ; GO:0045061

Currently undefined

Proposed definition: Processes of T-cell selection that occur in the thymus.

Reference: ISBN:0781735149, PMID:12414722

25) negative thymic T-cell selection ; GO:0045060

Currently undefined

Proposed definition: The process of elimination of immature T-cells in the thymus which react strongly with self-antigens.

Reference: ISBN:0781735149, PMID:12414722

26) positive thymic T-cell selection ; GO:0045059

Currently undefined

Proposed definition: The process of sparing immature T-cells in the thymus which react with self-MHC protein complexes with low affinity levels from apoptotic death.

Reference: ISBN:0781735149, PMID:12414722

Obsoletion

27) thymocyte differentiation ; GO:0046652

Current Definition: Processes by which a relatively unspecialized hemopoietic stem cell acquires the specialized features of a thymocyte, a lymphocyte found in the thymus.

The problem with this term is that thymocytes are immature T cells, and thus the term is redundant with GO:0030217 T- cell differentiation and its children. The definition and current placement in the DAG also seems to imply that thymocytes are some other kindgit/tags{/sha}

gocentral commented 19 years ago

Original comment by: addiehl

gocentral commented 19 years ago

Original comment by: addiehl

gocentral commented 19 years ago

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That all looks fine to me Alex. I don't see any problem with the overlapping terms.

Jane

Original comment by: jl242

gocentral commented 19 years ago

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I forgot to add two new synonyms for GO:0030217 T-cell differentiation:

Synonym 1: T-cell development Synonym 2: T cell development

These synonyms are needed because immunologists speak of 'T cell development' rather than 'T cell differentiation,' in most cases and need to be able to find the GO term directly. These are exact synonyms.

Thanks,

Alex

Original comment by: addiehl

gocentral commented 19 years ago

Original comment by: jl242

gocentral commented 19 years ago

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A few comments:

I made 'CD4-positive/CD8-positive T-cell lineage commitment' 'CD4-positive and CD8-positive T-cell lineage commitment' instead (latter as exact synonym) - we like to try and avoid using punctuation marks like / where possible because they can be so ambiguous.

Looks like we need an intermediate parent term to 'CD4-positive and CD8-positive T-cell lineage commitment' - it's much more specific that most of its siblings e.g. muscle cell fate commitment. Something like 'T-cell commitment'? (that's a total guess - please put me right!).

Original comment by: jl242

gocentral commented 19 years ago

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Two comments:

1) As we discussed by email, GO:0046652 thymocyte differentiation should be merged with GO:0030217 T-cell differentiation and the term "thymocyte differentiation" should be entered as a narrow synonym (not all types of T cells differentiate in the thymus).

2) I am still considering the types of T-cell commitment terms that will be needed and their relationship to other development terms. If you could proceed with all the new terms and term changes but the commitment terms, I would be very pleased, and I promise to get back shortly about the commitment terms.

Thanks,

Alex

Original comment by: addiehl

gocentral commented 19 years ago

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Alex, for this term:

19) Term Name: pre-T-cell receptor complex

Do you also want to give it a part_of parentage? Presumably it's a cell-surface receptor so maybe 'integral to plasma membrane ; GO:0005887' as a second parent?

Original comment by: jl242

gocentral commented 19 years ago

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Jane,

Yes that would be okay.

Hold off on committing the terms until you see my revision of this proposal, as I have decided to organize some of the terms differently.

Thanks,

Alex

Original comment by: addiehl

gocentral commented 19 years ago

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Alex - I've just committed those changes (below) before the file started becoming too diverged with the cvs repository. I know you've got some further changes you want to make to these terms and that's fine. Can you put them in a new SF entry though, cos this one's getting a bit long to scroll through! Give it a high priority and I'll get on to it asap.

thanks,

Jane

Added new terms:

1) Term Name: beta selection ; GO:0043366 2) Term Name: CD4-positive T-cell differentiation ; GO:0043367 3) Term Name: CD4-positive T-cell lineage commitment ; GO:0043368 4) Term Name: regulation of CD4-positive T-cell differentiation ; GO:0043369 5) Term Name: negative regulation of CD4-positive T-cell differentiation ; GO:0043370 6) Term Name: positive regulation of CD4-positive T-cell differentiation ; GO:0043371 7) Term Name: CD8-positive T-cell differentiation ; GO:0043372 8) Term Name: CD8-positive T-cell lineage commitment ; GO:0043373 9) Term Name: regulation of CD8-positive T-cell differentiation ; GO:0043374 10) Term Name: negative regulation of CD8-positive T-cell differentiation ; GO:0043375 11) Term Name: positive regulation of CD8-positive T-cell differentiation ; GO:0043376 12) Term Name: memory T-cell differentiation ; GO:0043377 13) Term Name: regulation of memory T-cell differentiation ; GO:0043378 14) Term Name: negative regulation of memory T-cell differentiation ; GO:0043379 15) Term Name: positive regulation of memory T-cell differentiation ; GO:0043380 16) Term Name: negative T-cell selection ; GO:0043381 17) Term Name: positive T-cell selection ; GO:0043382 18) Term Name: CD4-positive/CD8-positive T-cell lineage commitment ; GO:0043383 *19) Term Name: pre-T-cell receptor complex ; GO:0043384

New Definitions

20) T-cell selection ; GO:0045058 21) extrathymic T-cell selection ; GO:0045062 22) negative extrathymic T-cell selection ; GO:0045068 23) positive extrathymic T-cell selection ; GO:0045067 24) thymic T-cell selection ; GO:0045061 25) negative thymic T-cell selection ; GO:0045060 *26) positive thymic T-cell selection ; GO:0045059

'thymocyte differentiation ; GO:0046652' merged into 'T-cell differentiation ; GO:0030217' with 'thymocyte differentiation' as a narrow synonym.

Original comment by: jl242

gocentral commented 19 years ago

Original comment by: jl242