International Journal of Celiac Disease, 2016, Vol. 4, No. 1, 1-3 Available online at http://pubs.sciepub.com/ijcd/4/1/5 © Science and Education Publishing DOI:10.12691/ijcd-4-1-5 It's Counting That Counts Michael N Marsh * Oxford University, UK *Corresponding author: mikemarshmd@uwclub.net Cite This Article: Michael N Marsh, “XIt's Counting That Counts.” International Journal of Celiac Disease, vol. 4, no. 1 (2016): 1-3. doi: 10.12691/ijcd-4-1-5. In the last issue of the journal, Siriweera and colleagues [1] revisit the controversial area of inter-epithelial space lymphocyte (IEL) "counting" in regard to the diagnosis of celiac disease (or, as I prefer, for good reason, gluten sensitivity). Their histologically-based approach is a further attempt to re-determine the diagnostic validity of this method of enumerating IEL. It was based on another definition of the 'control' upper limit for normal mucosae, but also to 'assess the diagnostic accuracy of existing criteria for IEL in diagnosis of celiac disease'. Briefly, based on x400 examinations of 3μm H&E sections of formalin-fixed tissue, their upper limits for control, and celiac, mucosae were 4/100 and 20/100 enterocytes, respectively. These values are exceptionally low for controls, while the ranges for each series were not given, so the extent of their overlap cannot be inferred. Conversely, the data published from our laboratory [2], based on strict morphometric criteria using oil-immersion optics with 1μm toluidine blue-stained Epon sections yielded 95% confidence limits of 5-27, and 14-61, respectively. Despite that attention to detail, there was a clear overlap between each nominal population, thus reinforcing the obvious conclusion that there is no magical "cut-off" point, because the lymphocyte response (like weight, blood pressure, height, acid secretion) is a graded characteristic [3]. That indicates that there never was, nor could be, clear-cut divisions, as if the two IEL populations (control and celiac) represented separate, bimodal populations. The results of every study published are also confirmatory of that truth, too, but is contrary to Lerner and Matthias [4]. Apart from a few references, there was no in-depth engagement by Siriweera with the considerable literature on IEL, and one which still remains unresolved, as is clear from the recent papers in this journal by Pena, and by Lerner & Matthias (and see similar recent explorations in Gastroenterology Hepatology: from Bed to Bench, 8(4), 2015). I was also rather surprised that Siriweera's counts were made on 'uninterrupted sections of epithelium comprising 500 enterocytes' which, in my experience, would be very difficult to achieve for normal mucosae and even more so for damaged specimens. Neither do they grade their celiac mucosae (whether one believes the so- called Marsh Classification [5] – albeit modified by so many others - or not). Now, that is very important because with the very early lesions, histological diagnosis may be well-nigh impossible, especially if the villi are tall and non- infiltrated (Marsh 0). As I was both a practising gastroenterologist and a laboratory-based investigator, it was always clear to me that the histology is but an aid to diagnosis, the latter being ultimately made, with all other relevant data weighed, at the bedside by the clinician in charge. Moreover, diagnosis is difficult in the early stages of evolving celiac disease irrespective of the diagnostic approach utilised [6]. This problem is diagnostically magnified by the current epidemic of so-called non- coeliac gluten sensitivity. This dilemma illustrates the fragile confirmation of coeliac disease in its earliest stages of development, and irrespective of the sophistication of the laboratory tests employed. My own view is that Siriweera's paper hardly contributes to this important debate, and certainly does not help in clarifying any of the issues arising. So, what are the issues arising? Many have been nicely revisited by Lerner & Matthias [4]: (i) effects of age on IEL (ii) presence of infections or parasites (H pylori, Giardiasis) (iii) genetic background (iv) geographic, environmental and cultural influences (v) role of other methodologies, including flow cytometry. These authors ask for a standardised methodological approach for enumerating IEL, but that is seemingly an impossible request, since as noted above, there have been innumerable papers on this subject without the slightest attention given towards a universally- agreed approach. Neither the official guidelines published by the American Gastroenterological Association nor the British Society of Gastroenterology have elucidated a preferred modus operandi. And as far as mucosal classification goes, the BSG paper [7] recommends any of the approaches available. One can conclude that neither the authors invited, nor the Organisations' representatives, acknowledged that this allegedly important histological tool employed widely should have been standardised – and accepted by everyone. One recent advance which does require attention, however, has seen the grouping of all mucosal specimens (Marsh 0, I and II) into the category termed by Rostami as "Microscopic Enteropathy" (The Bucharest Consensus) [8]. Here it is recognised, and quite rightly, that a list of differential diagnoses obtains for each mucosal category, thereby overcoming the somewhat ridiculous view that, for example, Marsh I and II lesions represent "non- specific" appearances. But there is no such histological entity as "non-specific": every tissue either reflects its physiological or pathological state when sampled. It is often scarcely recognised that the Marsh III lesion is