MARGINAL NEUTROPHIL POOL SIZE IN NORMAL SUBJECTS AND NEUTROPENIC PATIENTS AS MEASURED BY EPINEPHRINE INFUSION

Abstract

The marginal granulocyte pool (MGP) was measured by epinephrine infusion in normal and neutropenic subjects. Neutrophil response curves to doses of 0.025 to 0.3 mg. in 3 normal subjects indicated that maximal neutrophil response was achieved by 0.1 mg. In 21 normal subjects, absolute neutrophils increased from 700 to 3100/.mu.l. The percentage increase ranged from 18-107% of baseline. The percent increase tended to be greater with low-normal baseline neutrophils than with high-normal neutrophils, although this relationship was not observed when increase was determined in absolute values. In neutropenic patients, mean percent increase of neutrophils was greater than observed in normal subjects, 121 vs. 50%. Although the increase expressed in absolute neutrophil numbers was less in subjects with lower baseline neutrophil concentrations, there was an inverse correlation between the baseline neutrophils and the percent increment following epinephrine. Mean increase was 200% in patients with less than 200 neutrophils/.mu.l, compared with 61% in patients with 1000 to 1500 neutrophils/.mu.l. Circulating granulocyte pool (CGP) size may be misleading with respect to total blood neutrophils and in a sense confirm the concept of shift neutropenia, a decreased CGP with normal total blood neutrophils. The inverse relationship between the sizes of the CGP and MGP as neutropenia becomes more profound suggests that shift neutropenia may be a normal physiologic mechanism rather than a distinct neutropenic syndrome.