Visualization of silver-enhanced reaction products from protein-and immuno-colloidal gold probes by laser scanning confocal microscopy in reflection mode.

We have employed a laser scanning confocal microscope in reflection mode to directly and indirectly visualize sites of deposition of silver-enhanced reaction products from colloidal gold probes. A direct approach was used for the localization of alpha-fetoprotein receptors in human myoblasts by incubating primary cultures with an alpha-fetoprotein-gold conjugate. For an indirect approach, cultured CEM cells, derived from a human T-lymphoma cell line, were incubated with a mouse monoclonal antibody to mature T-cells, followed by a gold-labelled antibody to mouse immunoglobulins. Multiple optical sections of each sample were collected by reflection laser scanning confocal microscopy and combined into three-dimensional renderings. A (non-confocal) transmission image was generated of each field for comparative purposes. The increasing use of reflection laser scanning confocal microscopy combined with colloidal gold conjugates as biological markers will probably be of considerable advantage in cytochemical analysis.