VARYING DETECTION OF PCNA IN SOLID TUMOR-CELLS - EFFECTS OF FIXATION AND DETERGENT

PCNA was immunohistochemically detected with a monoclonal antibody to PCNA in both formalin fixed-paraffin embedded and frozen sections of t issue specimens from human solid tumors. The percent of PCNA positive cells (PCNA score), extremely high in formalin fixed, paraffin embedde d tissue sections, was decreased in frozen sections from the same tumo r. The treatment of frozen sections with Triton X-100 further diminish ed the PCNA score as compared with that of frozen sections without suc h a treatment. These results suggest that there are at least 3 subpopu lations of PCNA within human solid tumor cells.