Immunocytochemistry in cytology. Comparative evaluation of different techniques.

Immunocytochemistry represents an important tool in diagnostic cytology. Its application, however, is of restricted value due to methodologic difficulties, leading in some cases to false-positive or false-negative results. This study examined the influence of different fixatives and modes of storage of cytologic cell preparations on immunoreactivity using immunoenzymatic techniques. Monoclonal and polyclonal antibodies were used on imprint preparations of breast lesions and tonsils and on bronchoalveolar lavages. A short fixation of the cytologic material with 0.05% glutaraldehyde or a commercially available spray fixative (Merckofix) enabled the immunolocalization of a considerable number of antigens. Optimal demonstration of some antigens, however, required the use of individual fixatives. Drying of cell preparations should be avoided at any step of the procedure to prevent false-positive or false-negative results. Smears stored in methanol or sucrose-MgCl2-glycerol solutions retained their immunoreactivity for several months. The results of this study are compared with those of previous reports, and the reasons for, and means of avoiding, frequent pitfalls in immunocytochemistry are discussed.