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...

The hypothesis that bacterial phagocytosis by human polymorphonuclear neutrophils (PMNs) stimulates MAPK cascades that regulate respiratory burst activation was tested. Extracellular response kinase (ERK) and p38 kinase, but not c-Jun NH2-terminal kinase, activities were increased within 5 min of phagocytosis of plasma-opsonized Staphylococcus aureus (S-SA), reached maximum at 20-30 min, and re...

Allergic bronchopulmonary aspergillosis (ABPA) in asthma is a severe, life-affecting disease that potentially affects over 4.8 million people globally. In the UK, ABPA is predominantly caused by the fungus Aspergillus fumigatus. Phagocytosis is important in clearance of this fungus, and Early Endosome Antigen 1 (EEA1) has been demonstrated to be involved in phagocytosis of fungi. We sought to i...

Previous studies have shown that the efficiency of phagocytosis is a function of cell cycle and that phagocytosis promotes cell cycle progression. Because phagocytosis is dependent on cellular receptors we hypothesized that Fcgamma receptors (FcgammaR) and complement receptors (CR) expression varied with cell cycle. Consequently, we used centrifugal elutriation of macrophage-like cells, fluores...

Phagocytosis occurs primarily through two main processes in macrophages: the Fcγ receptor- and the integrin αMβ2-mediated processes. Complement C3bi-opsonized particles are known to be engulfed through integrin αMβ2-mediated process, which is regulated by RhoA GTPase. C3 toxin fused with Tat-peptide (Tat-C3 toxin), an inhibitor of the Rho GTPases, was shown to markedly inhibit the phagocytosis ...

IgG antibodies play a role in malaria immunity, but whether and how IgM protects from the biology of Plasmodium falciparum (Pf)–specific B cells is unclear. In Mali cohort spanning infants to adults, we conducted longitudinal analyses Pf- influenza-specific cells. We found that Pf-specific memory (MBCs) are disproportionally IgM+ only gradually shift IgG+ with age, contrast MBCs predominantly i...

A 175-kD mannose-specific receptor has been described in macrophages which appears to mediate pinocytosis and phagocytosis. A mannose-specific receptor has also been found on retinal pigment epithelial cells (RPE). Its role was examined in the phagocytosis of photoreceptor outer segments (ROS) by the RPE. All testing was done on cultured RPE cells challenged with fluorescein isothiocyanate (FIT...

Macrophage activation resulting from phagocytosis has the potential to modulate human immunodeficiency virus (HIV) replication. We have determined the effects of phagocytosis of particulate stimuli on transcription and release of HIV. Using THP-1 and Mono Mac 6 human monocytic cell lines transfected with HIV long terminal repeat sequence chloramphenicol acetyltransferase (LTR CAT) constructs we...

BACKGROUND The mechanisms of thrombocytopenia and platelet phagocytosis in dengue illness are not fully understood. METHODS A prospective hospital-based study was conducted to examine the relationships between platelet counts, serum thrombopoietin (TPO) levels, and platelet apoptosis and phagocytosis in 81 patients with secondary dengue virus (DV) infections and 38 healthy volunteers. The apo...

Phagocytosis is a highly conserved aspect of innate immunity. We used Drosophila melanogaster S2 cells as a model system to study the phagocytosis of Candida albicans, the major fungal pathogen of humans, by screening an RNAi library representing 7,216 fly genes conserved among metazoans. After rescreening the initial genes identified and eliminating certain classes of housekeeping genes, we id...