Cell surface receptors antigenic

Fig. I. Endocytic pathways used by cells to internalize soluble macromolecules [25] fluid-phase pinocytosis (1), adsorptive pinocytosis (2), and receptor-mediated endocytosis (pinocytosis) (6). Each of these processes involves a formation of a sealed vesicle formed from the plasma membrane which encloses part of the extracellular medium. The internalization of a polymer-drug conjugate (P-D), and targeted polymer-drug conjugate ( => —P-D) is shown. Other abbreviations — = cell surface receptor/antigen 1 = clathrin molecule X = lysosomal enzyme. Fluid-phase pinocytosis (1) and adsorptive pinocytosis (2) are nonspecific processes which direct the macromolecule into the lysosomal compartment of the cell. Once P-D is internalized, whether by (1) or (2), the resulting endosome (3) is ultimately fused with a primary lysosome (4) forming a secondary lysosome (5). In the latter compartment P-D is in contact with several types of lysosomal enzymes. The membrane of (5) is impermeable to macromolecules. Consequently, the structure of P-D may be designed in such...

IL-2-stimulated cytotoxic T cells appear even more efficacious than LAK cells in promoting tumour regression. The approach adopted here entails removal of a tumour biopsy, followed by isolation of T-lymphocytes present within the tumour. These tumour-infiltrating lymphocytes (TILs) are cytotoxic T-lymphocytes that apparently display a cell surface receptor which specifically binds the tumour antigen in question. They are thus tumour-specific cells. Further activation of these TILs by in vitro culturing in the presence of IL-2, followed by reintroduction into the patient along with IL-2, promoted partial/full tumour regression in well over 50 per cent of treated patients. 

Antibodies that, by binding to the cell surface antigen, mark the tumour cell for destruction. NK cells and macrophages express cell surface receptors that bind to the antibody Fc region (Box 13.2). Thus, antibody bound to tumour antigens directs these immune elements directly to tumour surface. Antibodies also activate complement, which is capable of directly lysing tumour cells. 

It is entirely possible that surface staining cannot be accomplished before fixation. Some antibody-antigen complexes cannot withstand chemical fixation and/or permeabilization. An empirical evaluation must be made. In this example, cells are first stained with a monoclonal antibody against a cell-surface receptor, fixed with ethanol, and then the DNA is stained with propidium iodide. The cells are analyzed for two-color fluorescence, the green of the fluorescein-labeled surface marker and the red of the labeled DNA intercalator. This approach works for antibody-antigens that are unaffected by fixation. 

There are three different kinds of lymphocytes that have specific functions T cells, B cells and NK cells. T cells develop in the thymus while B cells develop in the adult bone marrow. The thymus and the bone marrow are the primary lymphoid organs where lymphocytes acquire specific cell surface receptors that give them the ability to recognize antigens. NK cells are cytotoxic lymphocytes that develop in the bone marrow. The phagocytes are made up of either monocytes (macrophages) or polymorphonuclear granulocytes, which include neutrophils, eosinophils and basophils. 

The TCR is composed of integral membrane protein that recognizes the antigen and as a consequence its activation produces an immune response to eliminate the antigen. This process results in the development of CD4+ or CD8+ cells from the precursor T cells. It involves other cell surface receptors and downstream signal transduction mechanisms. 

Helenius, A. Morein, B. Fries, E. Simons, K. Robinson, P. Shirrmacher, V. Terhorst, C. Strominger, J.L. Human (HLA-A and HLA-B) and murine (H-2K and H2-D) histocompatibility antigens are cell surface receptors for Semliki Forest virus. 

So far, selection of ligand for cell surface receptors or antigens has required the availability of the target receptor in its purified form [15-17, 23-28]. In some... 

Antibodies directed to antigens that are components of cell surface receptors are often pathogenic in vivo (such as ion channel antibodies and, possibly, mGluRl antibodies) [95, 182, 183], The pathogenic relevance of antibodies to intracellular targets is much more controversial, but antinuclear antibodies are reported to be pathogenic in some diseases such as systemic lupus erythematosus [184]. 

Interferon gamma binds to different cell surface receptors than alpha and beta Specific effect of interferon gamma include enhancement of oxidative metabolism of macrophages, antibody-dependent cellular cytotoxicity, activation of natural killer cells, and expression of Fc and major histocompatibility antigens While all alpha interferon have similar biological effects, not all activities shared by each and in many cases the extent of activity various substantially for each interferon subtype... 

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