Differential immunofluorescent staining of polymorphonuclear leucocytes for discriminating between surface bound and...

Discrimination between immunoglobulin on the surface of polymorphonuclear leucocytes and immunoglobulin internalised as a result of phagocytosis has been achieved by direct immunofluorescent staining with fluorescein and rhodamine antiglobulin conjugates of identical specificity applied sequentially to live cells in suspension and after fixation on microscope slides. Surface bound antigen is recognised by double staining whereas internalised material is stained only by the conjugate applied to the fixed preparation. This differential staining procedure was evaluated in a model system in which normal PMNs were exposed to small (less than 20 s) and large (greater than 90 s) aggregates of human IgG.