Morphometric analysis of intestinal mucosa. VI--Principles in enumerating intra-epithelial lymphocytes.

The mucosal response by intra-epithelial lymphocytes (IEL) to antigenic challenge is a useful monitor of local immune activity. Conventional counts of IEL (determined as profile ratios of IEL to enterocyte nuclei) are inaccurate, and over-estimate values by a factor of two, both for disease-control mucosae and untreated 'flat' gluten-sensitized mucosae. Two further proofs are advanced in this paper which expose the inaccuracy of conventional profile-density IEL counts. New ranges (log-transformed data) indicate a disease-control mean of 11 IEL per 100 enterocytes (95% confidence limits 5-27) and 29 IEL per 100 enterocytes (95% confidence limits 14-61) for untreated flat gluten-sensitive mucosae. For simplicity, if conventional IEL "counts" are halved, correct values (based on precise morphometric analyses) are easily obtained for comparative and other purposes.