Human peripheral blood large granular lymphocytes (LGL) - that is, cells with intracytoplasmic azurophilic (electron-dose) granules, with a positivity for the cytochemical localization of certain acid hydrolases, and with acid surface receptors for the Fc portion of IgG - have been purified on Percoll density gradients. Approximately 30% of these cells expressed receptors for the third complement component (C3R). They were separated into C3R-positive and C3R-negative cells. C3R- cells had a significantly greater natural killer (NK) activity against K562 target cells than C3R+ cells. This difference was unrelated to the presence in the C3R+ cells of a contaminant cell type incapable of NK activity, since cytochemical and ultrastructural analysis revealed that C3R+ and C3R- fractions contained comparable LGL numbers. Agarose cytotoxicity assays at the single-cell level demonstrated that C3R+ LGL contained a large number of cells that bound to but did not lyse the target. The remaining fully cytotoxic C3R+ LGL had, however, the same killing and recycling properties as the cells from the C3R- fraction. Electron microscopy and cytochemical studies showed that C3R+ cells has fewer electron-dense granules than C3R- cells and stained more faintly for the localization of α-naphtyl acetate esterase. In contrast to cells, C3R+ LGL displayed morphological features that an active process of granule formation was taking place. Taken together, the data indicate that C3R+ cells represent a discrete subset or a maturational stage of LGL.
|Number of pages||10|
|Journal||Scandinavian Journal of Immunology|
|Publication status||Published - 1983|
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