Origin of Neutrophils in Pernicious Anemia (Cooke's Macropolycytes)

It has been aptly mentioned by Heck and Watkins 1 that there is little in the American medical literature concerning the value of neutrophils in pernicious anemia as an aid to diagnosis. There is practically nothing in the American literature dealing with the origin of these cells. Cooke, 2 after studying cells in the peripheral blood for many years, finally advanced three hypotheses to explain the source of large hypersegmented hyperpolymorphic neutrophils in pernicious anemia, which he called macropolycytes I, II, and III. These are the same cells which have been called pernicious anemia neutrophils and have been accurately described by Downey. 3 As will be seen later, the various types of macropolycytes described by Cooke are in reality morphologic variations of cells belonging to the same series of pathologic neutrophils. The origin of these atypical cells was contemplated in the following hypotheses formulated by Cooke: 2 First, there is