It is currently unclear whether the T cell dysfunctions observed during active systemic lupus erythematosus (SLE) reflect a disorder intrinsic to the T cell or defects that result from interaction with anti-T cell autoantibody. To determine whether a disorder intrinsic to the T cell exists in SLE, the T cell capping mechanism was selected as a model of cellular function. The normal T cell cappi...

A novel approach for the analysis of membrane proteins involved in ligand-induced surface receptor patching and capping is described. The technique is based on the use of immunolactoperoxidase (immuno-LPO) conjugates which catalyze the iodination of those surface proteins with available tyrosine groups that are located in the immediate vicinity of the patch or cap of a particular antigen. We ha...

Interaction of ligands with the antigen receptor on B lymphocytes leads to a rapid and dramatic series of surface and cytoplasmic events that have been mostly studied using as a probe anti-immunoglobulin (Ig) antibodies (anti-Ig) in murine lymphocytes. Four separate but overlapping events can be identified as occurring during capping: (a) an initial formation of aggregates of variable sizes on ...

We propose a new theory of cell surface capping based on the principles of nucleation. When antibody interacts with cell surface molecules, the molecules initially form small aggregates called patches that later coalesce into a large aggregate called a cap. While a cap can form by patches being pulled together by action of the cell's cytoskeleton, in the case of some molecules, disruption of th...

Polyspecific antibodies bound to Entamoeba induced surface redistribution of membrane components toward the uroid region. Capping of surface antigens was obtained with a single layer of antibodies in E. histolytica and E. invadens. This surface segregation progressed to a large accumulation of folded plasma membrane that extruded as a defined vesicular cap. A spontaneous release of the cap at t...

Lymphoid cells from 20 patients with lymphoproliferative disorders, including chronic lymphocytic leukemia, hairy cell leukemia, Sezary syndrome, lymphoma, and lymphadenitis, were studied for redistribution of surface membrane immunoglobulins (SmIg) and concanavalin A (Con-A) receptors. Fluorescein-labeled polyvalent goat anti-human immunoglobulin and fluoresceinated concanavalin A were used as...

Pathogenic trypanosomes undergo antigenic variation, whereby the glycoprotein molecules constituting the cell coat are changed, the parasite thus evading the host's immune response. On application of homologous antiserum in indirect immunofluorescence to a given variable antigen type of Trypanosoma brucei, the surface variable antigen moves to the flagellar pocket region, which overlies the Gol...

In the previous study, lymphocyte surface molecules were separated into two subsets depending on whether capping was associated was associated with redistribution of cytoplasmic myosin. In the present study, the effects of the local anesthetic chlorpromazine and of the Ca2+ ionophore A23187 were compared. Both drugs affected the surface redistribution of immunoglobulin (Ig), Fc receptors, and t...

We report on the use of surface-sensitive techniques (x-ray absorption spectroscopy and x-ray magnetic circular dichroism) to investigate interfacial effects in sputtered manganite thin films, La2/3Ca1/3MnO3 (LCMO) and La2/3Sr1/3MnO3 (LSMO), with different capping layers [MgO, LaAlO3 (LAO), SrTiO3 (STO), NdGaO3 (NGO), and Au]. To ensure surface sensitivity, data were acquired by using the total...

Colloidal semiconductor nanocrystals in the range 1-10 nm are promising building blocks for future nanodevices since they show strong quantum confinement effects even at room temperature [1,2]. Colloidal semiconductor nanocrystals consist of an inorganic core, having the same crystal structure as the corresponding bulk semiconductor, surrounded by a shell of capping molecules. These cappping mo...