A method for specifically detecting internal immunoglobulin by immunofluorescence.

The detection of specifically internal immunoglobulin by staining of fixed preparations of lymphoid cells with appropriate fluorescein-conjugated antisera can be hampered by binding of the conjugates to membrane-bound immunoglobulin. Without preventing staining through membrane-bound immunoglobulin, it is impossible to be sure whether lightly stained cells contain only small amounts of immunoglobulin or wehter the staining is entirely due to the membrane-bound material. Surface immunoglobulin can be stripped from tonsil cells prior to making preparation, and this can be achieved without loss of viable cells. As compared with untreated preparations, pronase-stripped smears contain little non-cellular debris and greatly reduced numbers of small lymphocytes faintly stained by polyvalent anti-human immunoglobulin. The remaining stained cells can be said to specifically contain internal immunoglobulin and are easily scored.