title: Fixation-dependent cytoplasmic false-positive staining with an immunoperoxidase method.
abstract: Fixation-dependent nonspecific staining with the unlabeled immunoperoxidase (PAP) method was studied using paraffin-embedded human spleen sections fixed in various fixatives; the specific primary antiserum was omitted or nonimmunized normal rabbit serum was used. Strong cytoplasmic staining of polymorphonuclear leucocytes and macrophages was found after fixation in acetone, alcoholic formalin (94% alcohol) and absolute ethanol. This staining was mainly produced by the second layer of the PAP method. The most probable explanation of this phenomenon is nonspecific protein-immunoglobulin interaction as a result of alcoholic or acetone fixation of the sections. The present findings point to the importance of controls for each case under study to avoid false-positive interpretations.
mesh_terms: D006801:Humans; D007106:Immune Sera; D007124:Immunoenzyme Techniques; D008264:Macrophages / Q000166:cytology; D009504:Neutrophils / Q000166:cytology; D013154:Spleen / Q000166:cytology* / Q000473:pathology; D013194:Staining and Labeling
chemical_list: D007106:Immune Sera