The cytoskeletal, actin-binding protein talin has been previously implicated in phagocytosis in Dictyostelium discoideum and mammalian phagocytes. However, its mechanism of action during internalization is not understood. Our data confirm that endogenous talin can occasionally be found at phagosomes forming around IgGand C3bi-opsonized red blood cells in macrophages. Remarkably, talin knockdown...

Mycobacterium leprae, an obligate intracellular pathogen, invades and multiplies within host mononuclear phagocytes. To understand M. leprae invasion better, we have investigated the role of phagocyte receptors and bacterium-bound ligands in phagocytosis of M. leprae by human monocytes. Complement receptors CR1 and CR3 mediate adherence and phagocytosis of M. leprae in nonimmune serum. Two MAbs...

Platelet transfusion is a very common lifesaving medical procedure. Not widely known is the fact that platelets, unlike other blood cells, rapidly leave the circulation if refrigerated prior to transfusion. This peculiarity requires blood services to store platelets at room temperature, limiting platelet supplies for clinical needs. Here, we describe the mechanism of this clearance system, a lo...

Cooperation among plasma membrane receptors in activating signal transduction cascades is not well understood. For almost 20 years, it has been clear that when a particulate foreign body is opsonized with complement as well as IgG, the efficiency of IgG effector functions is markedly enhanced. However, the molecular mechanisms involved in cooperation between IgG Fc receptors and complement rece...

Receptors for C3 bind ligand and generate intracellular signals that lead to the engulfment of C3-coated particles. Recent experiments suggest that both the binding and the subsequent signal transduction activities of C3 receptors can be regulated. Cultured human monocytes (MO) 1 express receptors for C3b (CR1) and C3bi (CR3) that bind ligand-coated particles but do not signal the cell to initi...

The inflammatory response to muscle-damaging exercise requires monocyte mobilization and adhesion. Complement receptor type 3 (CR3) and macrophage inflammatory protein (MIP)-1β enables monocyte recruitment, adhesion, and subsequent infiltration into damaged muscle tissue. The purpose of this study was to examine the effects of cold water immersion (CWI) and/or β-hydroxy-β-methylbutyrate free ac...

Neutrophils provide an innate immune response to tissues infected with fungal pathogens such as Candida albicans. This response is tightly regulated in part through the interaction of integrins with extracellular matrix ligands that are distributed within infected tissues. The β(2) integrin, CR3 (CD11b/CD18), is unique among integrins in containing a lectin-like domain that binds the fungal pat...

Bordetella pertussis, the causative agent of whooping cough, adheres to human monocytes/macrophages by means of a bacterial surface-associated protein, filamentous hemagglutinin (FHA) and the leukocyte integrin, complement receptor 3 (CR3, ~xmfl2, CDllb/CD18). We show that an FHA Arg-Gly-Asp site induces enhanced R pertussis binding to monocytes, and that this enhancement is blocked by antibodi...

A crystal field analysis of the energy level structure of Cr3+ in MgO crystal is performed, using the exchange charge model of the crystal field theory. The crystal field parameters acting on the optical electrons of Cr3+ are calculated from the crystal structure data; good agreement between the calculated and observed energy levels of Cr3+ in the title host is demonstrated. The Stokes shift S=...

Complement receptor 3 (CR3, CD11b/CD18) is a multi-functional receptor expressed predominantly on myeloid and natural killer (NK) cells. The R77H variant of CD11b, encoded by the ITGAM rs1143679 polymorphism, is associated robustly with development of the autoimmune disease systemic lupus erythematosus (SLE) and impairs CR3 function, including its regulatory role on monocyte immune signalling. ...