Surface bound or cytoplasmic immunoglobulins: interpretation of the immunofluorescence observed in cytocentrifuge slides of human lymphocytes.

Results of immunofluorescence observations in the study of normal and malignant blood lymphocytes are described. Data which support the proposition that most membrane bound immunoglobulin molecules are stable enough to remain intact during cytocentrifuge slide preparation are presented. Therefore not all positive cells in a fixed cytocentrifuge slide should be considered as containing cytoplasmic immunoglobulins. A correct interpretation is essential because of its bearing on our concepts of B lymphocyte differentiation.