Comparison of the hematologic effects of 2-butoxyethanol using two types of hematology analyzers

Earlier reports from this laboratory indicated that 2-butoxyethanol (BE) causes acute hemolytic anemia in rats as evidenced by a time- and dose-dependent decrease in the number of red blood cells, in hemoglobin concentrations, and in hematocrits (HCT). Subsequent studies showed that treatment with BE causes an early increase in HCT and mean cell volume (MCV). Since this effect went undetected in our early work and resulted in the publication of inaccurate information, present studies were designed to reinvestigate the hematologic effects of BE using the laser-based hematology analyzer which was used in the early studies and an impedance-based hematology analyzer, simultaneously. Packed cell volumes (PCV; spun HCT) were also performed on all blood samples. Male F344 rats were treated with 0, 125, 250, or 500 mg BE/kg (po) and blood was collected from the retro-orbital venous plexus at 1, 2, 4, 8, and 24 hr after dosing. Hematology profiles of BE-treated rats obtained from the impedance-based analyzer showed an early dose- and time-dependent increase in HCTs and MCVs. In contrast, analysis of the same blood samples using the laser-based analyzer showed a dose- and time-dependent decrease in HCTs with little or no change in MCVs. Changes observed in PCVs were consistent with results obtained from the impedance-based analyzer. Therefore, under the experimental conditions of this and previous studies, the laser-based analyzer was unable to detect early increases in HCTs and MCVs in rats treated with BE. Finally, these data explain the different principles utilized to measure cell size by both instruments as they relate to the hematologic effects of BE. Moreover, present data show that BE-induced hemolysis of erythrocytes is preceded by a quantitatively unique and massive swelling suggesting the erythrocyte membrane as the target.