Enumeration of lymphocyte-target cell conjugates by cytofluorometry.

Using fluorescein-labeled effector lymphocytes and tetramethyl rhodamine-labeled target cells a cytofluorometric method is described for the detection and quantification of lymphocyte-target cell cluster (conjugate) formation. Conjugation levels measured by cytofluorography correspond well with those scored microscopically. The method has so far been used successfully to monitor conjugate formation by specifically sensitized cytotoxic T lymphocytes (CTL). In preliminary experiments it has been applied to nonspecific, lectin concanavalin A-dependent conjugate formation by CTL, as well as to conjugates formed by hybridoma CTL. The procedure has potential application in other cell-cell interactions, relevant to immunology as well as to cell biology.