Characterization of IL-2-dependent cytotoxic T-cell clones. II. Cell-surface phenotypes, histochemical and ultrastructural properties
This report examines the histochemical staining patterns, ultrastructure, and cell-surface phenotypes of six antigen-specific T-cell clones. Histochemical analyses indicated that all cell lines expressed alpha-napthyl butyrate esterase characteristic of the monocytic isoenzyme, intense napthol AS-D chloroacetate reactivity characteristic of granulocytes, and were negative for leucoperoxidase, alkaline phosphatase, and Sudan black. Only one clone stained weakly for acid phosphatase. The esterase staining patterns became evident in newly established cell lines after growth for only 1 week in interleukin 2-conditioned medium. Ultrastructurally, the outstanding feature was numerous membrane-bound granules containing a complex-appearing globular material. The cell-surface phenotypes of the lines as determined by protein A-sheep red blood cell rosetting and indirect immunofluorescence was Ly-5+, T200+, Qa-5-, MAC-1-, and Lyt-1+,2,3- for the helper line and Lyt-1-2,3+ for the five cytotoxic lines. By quantitative absorption analyses, low levels of Lyt-1 antigens were detected on all examined cytotoxic lines. The results strengthen the view that long-term T-cell lines can retain normal T-cell characteristics while also expressing markers that are either absent or in undetectable levels on uncultured T lymphocytes. The presence of the esterases may be associated with an expanded functional role in the T-cell lines.