Human thymocytes expressing gamma/delta T‐cell receptors

M. C. Mingari, P. Varese, C. Bottino, G. Tambussi, L. Moretta

Research output: Contribution to journalArticlepeer-review

Abstract

Expression of T‐cell receptors of gamma/delta type characterizes a small subset of peripheral T lymphocytes which is homogeneously composed of cytolytic cells and, in most instances, lack CD4 and CD8 differentiation antigens. By the use of anti‐TCR gamma/delta MAbs it is possible to identify two distinct subsets of TCR gamma/delta+ cells that are characterized by a Cγl or Cγ2‐encoded forms of gamma‐chain, respectively. While the BB3 MAb‐reactive (Cγl encoded) cell subset is prevalent in peripheral blood (PB), these cells represent <10% in TCR gamma/delta+ thymocyte populations. In thymus, the majority of cells was found to react with delta‐TCSI (or Al3) MAbs. Culture of CD48thymocytes (highly enriched in TCR gamma/delta‐cells) in IL‐2 resulted in the de novo expression of CD8 surface antigen and of non MHC‐restricted cytolytic activity. Cloning of CD48thymocytes resulted, for the most part, in CD3+TCR gamma/delta‐ cells. Moreover, the majority of clones expressed the unusual delta‐TCSI+ CD8+ phenotype and lysed the NK‐sensitive K562 target cells. Analysis of the immunoprecipitated TCR molecules showed the existence of the (rare) heavy (55 kDa) form of gamma‐chain. A redirected killing assay using murine P815 target cells and appropriate “stimulatory” antibodies was further employed for functional analysis of thymus‐derived TCR gamma/delta+ clones. While anti‐CD3 MAbs efficiently triggered the cytolytic activity of all clones irrespective of their phenotype, MAbs directed to TCR gamma/delta induced efficient lysis only of BB3+ or delta‐TCSI+CD8 clones, but not of delta‐TCSI+CD8+ clones. Therefore, it appears that a receptor type which appears to be relatively inefficient in mediating activation signals is predominant in the thymus and rare in the periphery.

Original languageEnglish
Pages (from-to)39-42
Number of pages4
JournalInternational Journal of Cancer
Volume44
Issue number1 S
DOIs
Publication statusPublished - 1989

ASJC Scopus subject areas

  • Medicine(all)
  • Oncology
  • Cancer Research

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