AUTOMATED SCREENING FOR CYTOMEGALOVIRUS-INFECTED CELLS USING IMAGE-ANALYSIS - COMPARISON OF 2 IMMUNOENZYMATIC STAINING METHODS WITH RESPECTTO COLOR SEGMENTATION

The detection of human cytomegalovirus (HCMV) infected poly-morphonucl ear leukocytes (PMNLs) for early finding of the pp65 antigen using aut omated image analysis has been improved. The routinely used immunoenzy me peroxidase (PO) labelling has been replaced by alkaline phosphatase (AP) using new fuchsin as substrate. The number of automatically dete cted false positive objects due to incomplete inactivation of endogeno us peroxidase and strong variations in counterstain intensity could be reduced by 81% using this AP staining method. The number of detected truly positive cells with both staining methods was not significantly different. Furthermore, a new image analysis system providing processi ng of colour images was evaluated. Since plain differences in absorpti on wavelength are required for colour segmentation, the red immune-sta ining was combined with a green counterstain using methyl green. Scree ning of AP- instead of PO-stained slides in combination with colour se gmentation resulted in a further reduction of the number of falsely de tected alarms from 61% to 11%. Consequently, the sensitivity of the au tomated detection was improved. For AP staining detection of cells in frequencies of approximately; one to one million was demonstrated. Scr eening for CMV-positive, alkaline phosphatase labelled cells using an image analysis system with colour segmentation resulted in a reduced f alse alarm rate, a better visual interpretation of the images and subs equently an increase in the sensitivity of the automated screening pro cess.