Volume dependent polymorphonuclear leukocytes fractions isolated by counterflow centrifugal elutriation: PMN volume does not correlate with PMN age.

We have previously reported that human peripheral blood polymorphonuclear leukocytes can be separated into at least six volume dependent fractions using counterflow centrifugal elutriation (CCE). Larger volume was shown to correlate with increased superoxide release with either the chemotactic peptide F-met-leu-phe (FMLP) or the tumor promotor phorbol myristate acetate (PMA). To help explain these findings we have examined volume dependent PMN fractions (VDPF) for PMN functions felt to be correlated to PMN age, ie, alkaline phosphatase activity, phagocytosis of opsonized particles, adherence to plastic, and directed movement to FMLP and zymosan activated serum. PMN alkaline phosphatase activity was found to be low in the smallest PMNs, increasing in the PMNs of intermediate size, and then decreasing again in the largest PMN functions. A similar relationship was noted for PMN phagocytic activity. No significant difference among VDPF in adherence to plastic or chemotaxis was found. Furthermore, no difference among VDPF was seen for receptor number or binding affinity of the ligands FMLP or phorbol dibutyrate. Total cellular activity of the NADPH dependent oxidase was, however, 200% greater in the largest compared to the smallest VDPF. Because of the lack of consistent correlation between "age" related PMN function and PMN volume, it is unlikely that PMN volume represents a manifestation of PMN age. It is likely that the increased oxidase activity seen among larger VDPF accounts for the more rapid oxidative burst previously noted.