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Unexpectedly late expression of intracellular CD3ϵ and TCR γδ proteins during adult thymus development

1999; Oxford University Press; Volume: 11; Issue: 10 Linguagem: Inglês

10.1093/intimm/11.10.1641

1460-2377

Anne Wilson, Myriam Capone, H. Robson MacDonald,

Immune Cell Function and Interaction

During adult thymus development immature CD4 -CD8 -[double-negative (DN)] precursor cells pass through four phenotypically distinct stages defined by expression of CD44 and CD25: CD44 hi CD25 - (DN1), CD44 hi CD25 ⍣ (DN2), CD44 lo CD25 ⍣ (DN3) and CD44 lo CD25 -(DN4).Although it is well established that the TCR β, γ and δ genes are rearranged and expressed in association with the CD3 components in DN thymocytes, the precise timing of expression of the TCR and CD3 proteins has not been determined.In this report we have utilized a sensitive intracellular (ic) staining technique to analyze the expression of ic CD3ε, TCR β and TCR γδ proteins in immature DN subsets.As expected from previous studies of TCR β rearrangement and mRNA expression, icTCR β ⍣ cells were first detected in the DN3 subset and their proportion increased thereafter.Surprisingly, however, both icCD3ε ⍣ and icTCR γδ ⍣ cells were detected at later stages of development than was predicted by molecular studies.In particular icCD3ε protein expression coincided with the transition from the DN2 to DN3 stage of development, whereas icTCR γδ protein expression was only detected in a minor subset of DN4 cells.The implications of these findings for αβ lineage divergence will be discussed.