Two subsets of human T lymphocytes expressing γ/δ antigen receptor are identifiable by monoclonal antibodies directed to two distinct molecular forms of the receptor

C. Bottino, G. Tambussi, S. Ferrini, E. Ciccone, P. Varese, M. C. Mingari, L. Moretta, A. Moretta

Research output: Contribution to journalArticle

Abstract

Two mAbs directed to the TCR-γ/δ were analyzed for their pattern of reactivity with CD3+WT31- cell populations or clones. In normal individuals, the BB3 mAb reacted with ~2/3 of peripheral blood CD3+WT31- lymphocytes, whereas δ-TCS-1 stained ~1/3 of such cells. In addition, the sum of the percentages of BB3+ and δ-TCS-1+ cells approximated the percentages of peripheral blood CD3+WT31- lymphocytes in seven normal donors tested. Also, in peripheral blood-derived polyclonal CD3+WT31- populations, cultured in IL-2, cells reacting with one or another mAb accounted for the whole cell population. On the other hand, only δ-TCS-1-reactive cells, but not BB3+ cells, could be detected in unfracionated as well as in CD4-8- thymocyte populations. Analysis of peripheral blood-derived CD3+WT31- clones showed that 70% of 72 clones analyzed reacted with BB3 mAb, but not with δ-TCS-1, mAb. On the other hand, δ-TCS-1 mAb stained the remaining BB3- clones. Five clones expressing medium-low amounts of CDS antigen were BB3- δ-TCS-1+. Both types of clones lysed the Fcγ receptor-bearing P815 target cell in the presence of anti-CD3 mAb (but not of mAb directed against HLA-DR, CD7 molecules, or TCR-α/β). In this cytolytic assay, BB3 mAb induced target cell lysis only by BB3+ clones, whereas δ-TCS-1 mAb was effective only with δ-TCS-1+ clones. The CD3-associated surface molecules expressed by BB3+ or δ-TCS-1+ clones were analyzed after cell surface iodination and immunoprecipitation with the corresponding anti-TCR mAb or with anti-CD3 mAb (in digitonin-containing buffer). In SDS-PAGE, molecules immunoprecipitated from 13 BB3+ clones displayed, under nonreducing conditions, a molecular weight of 80 kD (in some cases, a minor 38-kD band could be detected). Under reducing conditions, two major components of 44 and 41 kD (and a minor component of 38 kD) were detected. On the other hand, TCR molecules immunoprecipitated from 11 different δ-TCS-1+ clones appeared as a diffuse band of 41-44 kD, both under reducing and nonreducing conditions (under non reducing condition, an additional 38-kD band was present). Therefore, BB3+ cells express a disulphide-linked form of TCR-γ/δ whereas δ-TCS-1+ cells express a non-disulphide-linked form. TCR molecules immunoprecipitated from BB3+ clones and analyzed by two-dimensional electrophoresis were represented, under reducing conditions, by two bands of ~38 and 41 kD displaying a similar pI and a third more basic 44 kD band. Under nonreducing conditions, BB3-reactive molecules were represented by a single 80-kD band (displaying an intermediate pI with respect to that of the reduced chains). TCR molecules immunoprecipitated from δ-TCS-1+ clones were represented, in both reducing and nonreducing conditions, by a diffuse 41-44-kD band (in which, however, two distinct components could be detected). In addition, a poorly labeled band of lower molecular weight was present. All these molecules displayed a similar pI and a high charge heterogeneity. Since similar molecular patterns were consistently detected among all BB3+ as well as among all δ-TCS-1+ clones analyzed, we conclude that BB3 and δ-TCS-1 mAbs identify two distinct molecular forms of TCR-γ/δ expressed by two different peripheral blood T cell subsets.

Original languageEnglish
Pages (from-to)491-505
Number of pages15
JournalJournal of Experimental Medicine
Volume168
Issue number2
Publication statusPublished - 1988

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ASJC Scopus subject areas

  • Immunology

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