The lymphocytes.

By convention the number is usually translated into number of lymphocytes per 100 intestinal lining cells variously called by their specific name enterocytes or broader name epithelial cell. Since the lymphocytes are between enterocytes or epithelial cells they are termed intraepithelial lymphocytes or IEL’s. When in excess the term is intraepithelial lymphocytosis.

Additional lymphocytes and other infection fighting cells, including mast cells, are stationed at the base of the intestinal villi. These cells are like Army or Marine troops held in reserve that are just waiting to be summoned to the fighting front at the surface of the intestinal villi, whenever the body believes it is being attacked or invaded.

The finding of increased IEL’s, or intraepithelial lymphocytosis, is the EARLIEST microscopic finding of Celiac disease and gluten injury though it is not specific for it. Cow’s milk protein allergy or sensitivity, giardia parasite and H. pylori bacteria, and viral infections can also be a cause. Usually recognizing increased numbers of lymphocytes in the tips of the intestinal villi is easy.

Most pathologist just “eye ball” the tips and subjectively judge whether there are increased numbers. Most state there either is or is not increased lymphocytes in the tips of the villi or intraepithelial lymphocytosis without specifically counting or reporting the numbers.

Special stains are available that highlight these lymphocytes allow them to be seen and counted easily. However, these stains are not done routinely and usually must be specifically requested, especially when minor changes of gluten injury are suspected, for example in someone who has already limited their diet intake of gluten.

For more than thirty years the cut off for abnormal was eight or more lymphocytes per villous tip or >40 IELs per 100 intestinal epithelial cell (enterocytes). In the past couple of years an IEL count of 7 or more villous tip or 20 enterocytes equivalent to 35 IELs/100 epithelial cells became the standard for defining abnormal intraepithelial lymphocytosis.