Figure 4.

Staining of HSIL cells in cervical smears by Pap stain alone (A) and with anti-Mcm5 antibody using a combination of immunoperoxidase and Pap staining (B and C) or immunofluorescence (D). (A and B) Cells are viewed at the scanning magnification used in the standard cervical screening test. The field in A stained with Pap stain alone contains several foci of HSIL cells (one is shown in detail, Inset), although they are difficult to recognize. The field in B stained with Pap stain and anti-Mcm5 antibodies contains immature-type HSIL cells, which are readily identified by the anti-Mcm5 antibody. As the Pap stain also has been performed on this latter sample, no information derived from the Pap stain has been lost (magnification: ×130). The field in C contains metaplastic type HSIL cells. Superimposition of the immunoperoxidase method on the Pap smear still allows detailed examination of the cellular and nuclear morphology of positively immunostained cells. The irregular nuclear outlines, prominent nucleoli, and abnormal chromatin patterns are still clearly visible (magnification: ×400). (D) Predominant nuclear immunofluorescence of Mcm5 (green), with a low level of cytoplasmic staining. DNA is counterstained with propidium iodide (red) so that immunoreactive nuclei appear yellow. HSIL cells stain positively, whereas the surrounding squamous and metaplastic cells are negative (magnification: ×243).