Intracellular free calcium (Ca2+ i) is thought to be an important second messenger for phagocyte functions. The fluorescent indicator Quin2 was used to measure and visualize [Ca2+]i in human neutrophils during chemotaxis toward, and phagocytosis of, opsonized zymosan. In neutrophils migrating toward zymosan, [Ca2+]i was highest in the lamellipodium. Neutrophils ingesting opsonized zymosan had t...

We have investigated the role in macrophage lysosomal enzyme release of arachidonate metabolites, extracellular divalent cations and cyclic AMP (cAMP) which modulate secretion in other cell types. Lysosomal enzyme secretion induced by zymosan was accompanied by release of malondialdehyde (MDA), which is derived from arachidonic acid via prostaglandin synthase. Blockade of MDA formation, by aspi...

In an attempt to explain the natural resistance •¿ of animals to heterologously transplanted tumors, it was theorized that the protective mechanism may be due to the properdin system (1,3). To test this hypothesis it was chosen to study the effect of zymosan on the transplantable human carcino ma of the colon (HR132) carried in weanling Wistar rats (2). Zymosan was selected rather than proper...

Heme oxygenase-1 (HO-1) is part of the integrated response to oxidative stress. This enzyme may exert anti-inflammatory effects in some animal models, although the precise mechanisms are not fully understood. We have examined the role of HO-1 in the inflammatory response induced by zymosan in the mouse air pouch. Zymosan administration induced HO-1 protein expression in leukocytes migrating to ...

Phagocytosis of zymosan by phagocytes is a widely used model of microbial recognition by the innate immune system. Live-cell imaging showed that fluorescent protein-fused Rab35 accumulated in the membranes of phagocytic cups and then dissociated from the membranes of newly formed phagosomes. By our novel pull-down assay for Rab35 activity, we found that Rab35 is deactivated immediately after zy...

Receptors involved in the phagocytosis of microorganisms under nonopsonic conditions have been little studied in neutrophils. Complement receptor type 3 (CR3) is a pattern recognition receptor able to internalize zymosan and C3bi-coated particles. We report that Abs directed against CR3 strongly inhibited nonopsonic phagocytosis of Mycobacterium kansasii in human neutrophils. In these cells CR3...

A luminol-dependent non-opsonized zymosan-induced chemiluminescence method for phagocytes in small quantities of whole blood (40 microliters; final dilution: 1:14) is described. It was characterized with reference to cellular and humoral components, and also applied to isolated neutrophils, eosinophils and monocytes. Normal values for whole blood chemiluminescence and for neutrophils, eosinophi...

Macrophages were obtained by peritoneal lavage from untreated mice or from mice which had received either Brewer's thioglycollate broth or a suspension of streptococcus A cell walls intraperitoneally 4 days before. 3 h after harvesting, adherent cells from untreated mice were allowed to phagocytose zymosan, formaldehyde-treated sheep erythrocytes, or latex beads. Phagocytosis was stopped after ...

We have previously observed that the phagocytosis of zymosan particles coated with complement by human polymorphonuclear leucocytes is accompanied by a time- and dose-dependent inhibition of phosphatidylcholine synthesis by transmethylation [García Gil, Alonso, Sánchez Crespo & Mato (1981) Biochem. Biophys. Res. Commun.101, 740-748]. The present studies show that phosphatidylcholine synthesis b...

The lipids of mouse peritoneal macrophages contain high levels (25 mole percent) of esterified arachidonic acid (20:4). Following in vitro exposure to unopsonized zymosan, these cells synthesize and release oxygenated products of 20:4. Maximal levels of zymosan ingestion promote the release of 40-50% of the 20:4 content of cultures without loss of viabilitiy. Release of radiolabel from macropha...