Disparity between circulating and marginated neutrophils: evidence from studies on the granulocyte alkaline phosphatase, a marker of cell maturity.
Since circulating and marginated human granulocytes are in rapid kinetic equilibrium, cells of these two compartments have been considered to be a homogeneous population. Our studies on the relationship between neutrophil maturity and the granulocyte alkaline phosphatase (GAP) activity cast doubt on this assumption. After iv administration of hydrocortisone, 12 male volunteers showed an augmentation in circulating granulocytes of 5730 cells/mm3, accompanied by an increase of band neutrophils from 18% to 33% (p less than 0.001). During this influx phase, the GAP activity decreased by 73% when measured cytochemically and by 28% when assayed biochemically (p less than 0.001 and less than 0.01, respectively). When granulocytes were demarginated by epinephrine, the mean count increased by 38%, accompanied by a rise in the portion of segmented forms from 74% to 79% (p less than 0.005) and by an increase of the cytochemical GAP activity by 24% (p less than 0.01). Exact complementary results were obtained during an excessive transient margination, the hemodialysis neutropenia: bands increased from 24% to 54% (p less than 0.02), while the cytochemical GAP dropped by 40% (p less than 0.005). Thus, our analysis of three situations with an acute transient shift of granulocytes indicates that functionally or chronologially "older" cells have a higher GAP activity, and that the transfer of granulocyte from the circulating to the marginal pool is selective.