The demonstration, staining and prevalences, in pathological and non-pathological specimens, of eosinophils in faeces

Although eosinophils are occasionally reported in mucus there has been no description of them in faecal samples. Attempts were made to demonstrate eosinophils in stool samples using several different staining techniques. Use of an acid dye, Acid Red 29, was found to be the simplest and most direct method of revealing eosinophils, producing very characteristic, orange-brown, sometimes red, staining of the intracellular granules that contain eosinophil cationic protein. In stool samples held at room temperature, without preservative, eosinophils remained demonstrable for a mean of 15 days and occasionally for a year. The peroxidase in the eosinophilic granules may help to preserve the cells. Eosinophils were found in 32 (14%) of 223 stool samples from patients with intestinal disease (including the results of several parasitic infections) but in none of 72 samples from apparently healthy hospital personnel (P<0.001). Eosinophils were never found in formed stool specimens that did not contain mucus. The demonstration of eosinophils in faecal samples may be a useful indicator of infection with intestinal helminths or of drug- or food-related digestive allergies.