Functional and metabolic heterogeneity among normal neutrophil subpopulations

In this study, normal human peripheral blood neutrophils were separated into subpopulations by centrifugation on discontinuous Percoll density gradients and further characterized according to various functional and metabolic capabilities. Chemotaxis was measured in response to optimal concentrations (20 nM) of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP). According to a population ratio analysis, the majority of cells that contain the highest proportion of fast migrating cells are isolated between the densities of 1.093 and 1.096 gm/ml. Arachidonic acid (AA) metabolism was also determined in neutrophil subpopulations. On initial density gradients, cells isolated from 1.084-1.087 gm/ml and incubated in the presence of exogenous [3H]AA produce 50% of the total [3H]LTB4 produced in response to ionophore A23187 stimulation; whereas after prelabeling with [3H]AA for 2 hr at 37 degrees C, the cells between 1.087 and 1.093 gm/ml are the most active at both releasing [3H]AA from the cellular phospholipids and synthesizing [3H]LTB4 (dpm/cell). These studies demonstrate the significant functional and metabolic heterogeneity that exists among normal neutrophil subpopulations.