Improved antigen detection in ethanol‐fixed cytologic specimens. A modified avidin‐biotin‐peroxidase complex (ABC) method

A new amplification technique is described for the detection of small amounts of antigen in ethanol‐fixed cytologic specimens and formalin‐fixed tissues. By adding a third antibody layer to the already sensitive avidin‐biotin immunoperoxidase system. we have demonstrated a considerable increase in both the quantitative and qualitative aspects of this immunostaining method. In evaluating this technique, we employed a previously defined small cell lung carcinoma cell surface antigen system and monoclonal antibodies.