Variation and error in eosinophil counts of blood and bone marrow.

By WILLIAM H. BEST, M.I)., AND MAX SAMTER, M.I). R ECENT interest in changing levels of circulating eosinophils as an index of I 1-oxysteroid output from the ad,’enal cortex demands a critical evaluation of the accuracy of individual counts, of the \‘alidit.y of comparing suecessive counts, and of physiologic variations in eosinophil level. The older literature is replete with investigations of eosinophil variation Un(ler many con(htions. It is questionable, however, how much reliance (‘an l)e placed On the available data. Schwarz’ in his extensive survey of changing levels of eosinophils in 1)100(1 and tissue examined the validity of various early reports. He cites a study by Tausz2 who studied the numbe,’ of eosinophils in a human during a thirty-day fast and found differential counts of 2.7 pet’ cent. in the beginning, 3.9 per cent at. the halfway mark and 4.7 per cent at the end of the expei’iment. While Tausz concluded that prolonged fasting results in an increase of eosinophils, Schwarz demonstrates that the absolute numbers were 257, 267, and 197 per en. mm., respectively ; in other wor(ls, that the level remained the same t.hi’oughout the perio(l of observation. Shottly after the description of a specific stain for the a granules of the eosinophils l)y Ehrlich,’ careful observers noted that. various stimuli coukl alter the number of circulating eosinophils. Such stimuli included selective stimulation of the autonomic nervous system,46 anaphylaxis, acute infectious diseases, and endoci’ine (lisorders.’ In general early studies concur,’ed that an increase in circulating eosinophils followed anaphylactie reactions, parasitic infestations, certain tumors, splenectomy, postinfectious convalescence, and the administration of parasympathomimetic drugs. Decrease in circulating eosinophils was seen subsequent to acute infections and the administration of sympathomimetic drugs such as epinephrine. From clinical observation, Schwarz proposed an endocrine regulation of circulating eosinophil levels. His postulate was that diminished function of the adrenal ot’ thyroid glands should result in an increase, hyperactivity in a decrease of blood eosinophils. With the advent of potent adreno-corticotropic hormone (ACTH), extracted from the anterior pituitary, various workers have examined the metabolic and hematologic response which follows its administration.8” One of the most consistent changes thus induced is a marked fall in circulating eosinophils. The maximal depression occurs at about four hours and subsides within twelve to twenty-