General Information

Immunocytochemical diagnostics

Immunocytochemical diagnostics is a dual predictive diagnostic test that evaluates p16INK4a და  Ki67 Cellular expression of proteins in a cervico-vaginal (mucous membrane of the cervix and vagina) sample. The sensitivity of the test is 94% and the specificity is 97% – in assessing the risk of high-grade cervical epithelium.

The p16INK4a protein is involved in the process of controlling the cell cycle and cell division.

Under normal conditions, the p16INK4a protein performs a tumor-suppressing function, blocking the uncontrolled proliferation of cervical cells infected with the papillomavirus.

Persistent HPV infections produce oncoproteins, which ultimately lead to genomic instability and uncontrolled proliferation of damaged epithelial cells.

Overexpression of the p16INK4a protein is a marker of the onset of cancerous transformation of HPV-infected cells and corresponds to a precancerous state of the cervix.

Ki67 protein is a marker of cell proliferation and is produced in the nucleus of a cell that is in the process of reproduction. The excessive production of p16INK4a and Ki67 proteins in the same cell indicates a violation of the cell cycle and the high oncogenic activity of the papillomavirus (HPV). Colposcopy evaluation of such a patient is necessary.

Recommendation for immunocytochemical study  Given:

• All patients with low-grade cervical intraepithelial lesion
• Patients with high-risk HPV types

Patient preparation

• For 24-48 hours before the sample is taken, the following are prohibited: sexual intercourse, vaginal douching, manipulations, use of vaginal medications, disinfectants, and lubricants.
• The sample should be collected between menstrual bleedings. In the presence of infection, the sample is taken after the course of treatment.
• If medical-surgical procedures are necessary, a vaginal sample should be taken before a manual examination or within 24 hours of colposcopy. The interval between electroresection, polypectomy, or the procedure after childbirth should be 1,5-3 months.

Material collection

Sample collection is performed using a vial and brush designed for liquid-based cytology, which allows for loss-free collection and undamaged transportation of the material.

Immunocytochemical studies are performed in a fully automated system that allows for simultaneous detection of both proteins.

The sample processing steps include antigen retrieval, inactivation of endogenous peroxidases (enzymes), incubation, and running of two immunocytochemical reactions, which are visualized with two different colors. The processed slides are examined by optical microscopy, regardless of cell morphology.

Interpretation of results

The CIN2+ immunocytochemical test (CINtec® PLUS) result is considered positive when simultaneous expression of p16INK4a and Ki67 proteins is observed in at least one cell.

Overexpression of p16INK4a protein is indicated by brown staining, and overexpression of Ki-67 protein is indicated by red staining. Dual cytochemical signal (detection of stains indicating both types of damage)

A double immunocytochemical signal (expressed in two colors) indicates dysregulation of the cell life cycle and changes in the genome, which is an indicator of high-risk damage.