I think much has been published about methods to assess Ki-67 immunohistochemical staining. Stringent counting, eyeballing and digital image analysis have been used to assess interobserver agreement. I am sure you will find lots of publications on this subject when you search in Pubmed.

In common practice pathologist do an estimate by counting a few representative fields. For accurate counting you need digital analysis software.

Please refer to Quickscore and H score papers. The former is very easy to use

The main problem of IHC - lack of standardized approach for most steps, including post-analytical. There are a lot of different IHC scoring systems. Most of them are combinative semiquantitative (including Allred, Quickscore, IRS, H-score), using addition and/or multiplication of valued parameters (number of "+" cells and force of staining). They all have different interpretation and different cut-off value for the results (from 1 to 10%).

One article about colorectal cancer analysis and cut-off value.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2014838/

Thanks very much for all the helpful suggestions.

Best wishes, Malcolm

Malcolm, the technical and medical staff should be specifically trained in the management and evaluation of the various antibodies and for appropriate information about their sensitivity and specificity, the method of performance evaluation and its possible clinical significance. The interpretation must always be made in conjunction with the clinical context and morphological findings.

Meet this aim by the suggested (Wardford and Fedchenko) methods are most suitable, since it is determined that the percentage of cells expressing the molecule and the strength of the reaction.

Thanks for all the feedback. My original question may have not have been phrased as well as I had intended. I'm a practicing diagnostic neuropathologist. I'm interested in understanding the perceptual principles behind diagnostic practice. We do not necessarily intuitively know how we subconsciously use a skill. I appreciate that methods of cell counting can be used to reliably determine proportions of stained cells. I'm interested in finding out more about the processes involved when professionals make perceptual estimates, and how training might improve this. 

Estimate Malcolm, the surgical pathology, so we tell the tissue fragments that sends the surgeon is an entire specialty, because we interpret injury and differential diagnosis.

The cell arrangement in each specimen we received has no control research and malignancies is challenging this interpretation. And when tissue needs immunohistochemistry pathologist has guidance on what you want and helps the definitive diagnosis.

You have to have direct communication with a human tissue pathologist if patients are treated.

If it is a research-controlled lower animals, it is different since the molecules to be investigated with immunohistochemistry is somewhat easily.