Immunofluorescence microscopy of paraffin-embedded human kidney specimens obtained by fine-needle aspiration biopsy

Recently, we have introduced an atraumatic fine-needle aspiration biopsy method to obtain human glomeruli for morphologic investigation. In the present study, immunofluorescence microscopy of paraffin-embedded, fine-needle specimens is described. The specimens were obtained by aspiration with a 10-mL syringe fitted to the fine-needle prepared from a lumbar puncture needle (Jintan Terumo). Embedding of the specimens into conventional paraffin blocks was carried out after pelleting them by centrifugation between processing steps in conical centrifuge tubes. Sections from the blocks were collected on small pieces of GelBond film (FMC Corporation) instead of objective slides, which prevented the detachment of small sections during enzyme treatment. Localization then was performed on deparaffinized trypsin-digested sections using fluorescein-labeled antibodies. The choice of fixative and digestive enzymes was found to have a marked effect on the localization; periodate-lysine-paraformaldehyde fixative and trypsin digestion gave the most reliable results.