John R. Apgar

Learn More
Galectin-3 is a beta-galactoside-binding protein implicated in diverse biological processes. We found that galectin-3 induced human monocyte migration in vitro in a dose-dependent manner, and it was chemotactic at high concentrations (1.0 microM) but chemokinetic at low concentrations (10-100 nM). Galectin-3-induced monocyte migration was inhibited by its(More)
Galectin-3 is a member of a large family of animal lectins. This protein is expressed abundantly by macrophages, but its function in this cell type is not well understood. We have studied the effect of galectin-3 gene targeting on phagocytosis, a major function of macrophages. Compared with wild-type macrophages, galectin-3-deficient (gal3-/-) cells(More)
Galectin-3 is a member of a beta-galactoside-binding animal lectin family. Previous in vitro studies have demonstrated that galectin-3 is involved in a number of activities; however, the roles of this lectin in physiological and pathological processes in vivo remain to be elucidated. Herein, we show, in a murine model of ovalbumin (OVA)-induced asthma that(More)
IgE is present in airway secretions from human patients with allergic rhinitis and bronchial asthma. However, the contribution of IgE present locally to the overall airway inflammation is not well understood. We hypothesize that Ag-specific IgE can capture airborne Ags and form immune complexes. These immune complexes may function as potent inducers of(More)
Crosslinking of the IgE receptor on rat basophilic leukemia (RBL) cells using the multivalent antigen DNP-BSA leads to a rapid and sustained increase in the filamentous actin content of the cells. Stimulation of RBL cells through the adenosine receptor also induces a very rapid polymerization of actin, which peaks in 45-60 s and is equivalent in magnitude(More)
Cross-linking of the immunoglobulin E receptor on rat basophilic leukemia (RBL)1 cells by multivalent antigen activates phosphatidylinositol (PI) kinase and phosphatidylinositol 4-phosphate (PIP) kinase leading to the increased production of PIP and phosphatidylinositol 4,5-bisphosphate (PIP2). Activators of protein kinase C (PKC), such as phorbol myristate(More)
A fraction of Bruton's tyrosine kinase (Btk) co-localizes with actin fibers upon stimulation of mast cells via the high affinity IgE receptor (FcepsilonRI). In this study, a molecular basis of the Btk co-localization with actin fibers is presented. Btk and other Tec family tyrosine kinases have a pleckstrin homology (PH) domain at their N termini. The PH(More)
Characterization of defects in a variant subline of RBL mast cells has revealed a biochemical event proximal to IgE receptor (Fc epsilon RI)-stimulated tyrosine phosphorylation that is required for multiple functional responses. This cell line, designated B6A4C1, is deficient in both Fc epsilon RI-mediated degranulation and biosynthesis of several lipid(More)
Cloned allospecific cytolytic T lymphocytes (CTL) adhere to purified class I alloantigen immobilized on plastic and degranulate in response to it. Binding and degranulation are inhibited by drugs that impair cytoskeletal function. Cytochalasins D and E, which interfere with microfilament function, and colchicine, which disrupts microtubules, were used and(More)
Cloned mutants of the human B lymphoblastoid cell line SB have been isolated using mutagenesis with ethyl methanesulfonate followed by negative selection with an anti-HLA-A2 serum and complement. Absorption analysis with 125I Staphylococcus aureus protein A binding to antibody sensitized cells. HLA typing, and immune precipitation analysis showed the(More)