Image analysis for accurately counting CD4+ and CD8+ T cells in human tissue.

In situ detection of specific cells offers a unique perspective on the spatial interactions between host immune cells and specific viral pathogens or cancers. Most immunohistochemistry techniques require manual cell counting on biopsied and fixed tissue sections. The availability of sophisticated software packages for analyzing fluorescently labeled tissue has made it possible to quickly and accurately quantitate the number of positive cells on such slides. Manual cell counting was compared to automatic cell counting using the program CellProfiler. The two techniques were used to count CD4+ and CD8+ T cells in human genital skin biopsies from herpesvirus type 2 (HSV-2) infected subjects. Manual counting and CellProfiler demonstrated high correlation both in cell counting as well as detection of immune cell "clustering" in tissue, an important visceral component of localized inflammation and characteristic of most chronic infections. Overall, CellProfiler is an effective and accurate method in addition to or replacement of manual cell counting of fluorescently labeled biopsies.