Clonal analysis of CD4-CD8- human thymocytes expressing a T cell receptor γ/δ chain. Direct evidence for the de novo expression of CD8 surface antigen and of cytolytic activity against tumor targets

M. C. Mingari, P. Varese, C. Bottino, G. Melioli, A. Moretta, L. Moretta

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CD4-CD8- human thymocytes were obtained by treating total thymocyte suspensions with anti-CD4 and anti-CD8 monoclonal antibodies (mAb) and complement. The resulting cell populations contained virtually no CD4+, CD8+ or WT31+ cells and 17-65% CD3+ cells. In addition, analysis of cell reactivity with delta-TCS-1 mAb (specific for the C(γ)2-encoded, nondisulfide-linked form of TcR γ/δ), revealed the presence of a variable proportion of δ-TCS-1+ cells (the % of δ-TCS-1+ cells were lower than the percentage of CD3+ cells). Upon culture in recombinant interleukin 2 (IL 2, in the presence of irradiated mononuclear cells), CD4-CD8- thymocytes underwent extensive proliferation. In addition, a progressive increase of CD8+ cells (but not of CD4+ or WT31+ cells) could be detected. Cells also progressively acquired cytolytic activity against K-562 or fresh melanoma cells. Fresh CD4-CD8- thymocytes were cloned under limiting dilution conditions. The cloning efficiencies were relatively high (1/3 cells); in addition, virtually all the clonal progenies obtained displayed cytolytic activity and expressed the CD3+WT31-δ-TCS-1+ surface phenotype. About half of the clones analyzed were CD8+, whereas none expressed CD4 antigens. We conclude that (a) only δ-TCS-1-reactive, TcR γ/δ+ cells can be isolated from CD4-CD8- thymocytes cultured in IL 2, and (b) the expression of CD8 antigen and of cytolytic activity reflects a true in vitro phenotypic change of CD8-, noncytolytic precursors (and not the preferential growth of few contaminating cells).

Original languageEnglish
Pages (from-to)1831-1834
Number of pages4
JournalEuropean Journal of Immunology
Issue number11
Publication statusPublished - 1988


ASJC Scopus subject areas

  • Immunology

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