The leukopenic index test described by Vaughan1 was considered by him to be of value in discovering the offending food in certain allergic diseases. The test is made as follows: Two white blood cell counts are made at ten minute intervals while the patient is fasting; the patient then eats the food to be tested, and additional counts are made at fifteen minute intervals for the first hour, with a final count at the end of one and one-half hours. A mean is established between the two counts made during fasting. A drop of more than 1,000 cells below that point is considered a positive reaction; a drop of less than 1,000 cells, if it occurs in all or nearly all the counts, is also considered positive. A fluctuation of 1,000 above or below the mean is considered normal.
This test has been applied to patients with bronchial asthma,