title: Activation of human neutrophils by phorbol ester decreases the cytoplasm compactness and the lactoferrin content of the granulocytes.
abstract: Human neutrophils isolated from the blood were incubated in vitro for 30 min with 25 ng/ml of phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, to study its effect on the fine structure of granulocytes and on the subcellular distribution of lactoferrin (Lf). Flow cytometry analysis of the human neutrophils showed that PMA induced a decrease in size and granularity of the cells. By electron microscopy, the PMA-treated cells showed numerous empty vesicles, smoothing of the cell surface, and a marked decrease in the compactness of the cytoplasmic ground substance. High-resolution immunogold ultracytochemistry showed that neutrophils lost most of their content in Lf after the PMA incubation. In thin sections, the cytoplasmic compartment of PMA-treated neutrophils contained an average of 1.03 +/- 0.3 Lf-positive vesicles per microns 2, whereas control granulocytes showed an average of 5.72 +/- 1.49 Lf vesicles per microns 2 of cytoplasm. Most of PMA-treated neutrophils kept some Lf-positive vesicles; a significant minority (10-15%) of the granulocytes showed cytological features of cell death. We conclude that the PMA-induced neutrophil activation is associated with microanatomical changes that include i) exocytosis of most, but not all, of the Lf-bearing vesicles; ii) rounding up of the cell outline; and iii) decrease in the compactness of the cytoplasmic ground substance.
authors.affiliation: Center for Experimental Cytology (INIC), Abel Salazar Institute for the Biomedical Sciences, University of Porto, Portugal.
authors.forename: N
authors.initials: N
authors.lastname: Esaguy
authors.forename: A P
authors.initials: AP
authors.lastname: Aguas
authors.forename: M
authors.initials: M
authors.lastname: Vilanova
authors.forename: M T
authors.initials: MT
authors.lastname: Silva
mesh_terms: D003593:Cytoplasm / Q000187:drug effects* / Q000648:ultrastructure; D005434:Flow Cytometry; D006046:Gold; D006098:Granulocytes / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D007781:Lactoferrin / Q000097:blood*; D008854:Microscopy, Electron; D009504:Neutrophils / Q000187:drug effects* / Q000648:ultrastructure; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D006046:Gold; D007781:Lactoferrin; D013755:Tetradecanoylphorbol Acetate