Antigen on the cell surface

Type O blood contains no antigens on the cell surface. In this case, any antibodies that the transfusion recipient may produce (anti-A or anti-B antibodies) have no antigens to attack. Therefore, no immune response against this blood exists. Individuals with type O blood are referred to as universal donors because this blood is suitable for transfusion in all individuals. 

IgG or IgM antibodies direct the immune response toward the antigen located on a cell (e.g., a red blood cell or thrombocyte). Macrophages, NK cells, and neutrophils are recruited by the antibodies to the site of the antigen on the cell surface and destroy the cell by phagocytosis or lysis. Additionally, complement activation will damage the cell (Fig. 6.32). The result, for example, where red cells are the targets is hemolytic anemia. 

The Fab region of the mAb reacts with its antigen on the cell surface. 

After electroporation into Raji cells, CD4 antigen-positive cells are enriched by repeated cell sorting and plasmids are recovered in Escherichia coli. Individual plasmids are retransfected and clones that induce expression of CD4 antigen on the cell surface were identified. Positive clones are sequenced and their deduced amino acid sequences are examined for the presence of a signal peptide. If a stretch of hydrophobic amino acids is detected immediately... 

Type II reactions involve cytotoxic antibodies (IgG or IgM mediated)/ which react with antigens on the cell surface the antigen-antibody combination then causes cell damage due to the presence of neutrophils and monocytes or complement-induced cell lysis. Examples of Type II reactions are the hemolytic anemias... 

H-Labeled PA has been prepared by two different methods. These reagents have not been widely tested, but reportedly are functionally stable. They have been used to detect antibody bound to antigen on the cell surface or immobilized to a solid support. Since [ H]PA may be a useful alternative to [ I]PA, the syntheses are included here. 

HIV-infected cells may be targeted either by the expression of viral antigens on the cell surface or by cell-surface markers that define the subset of activated CD4+ cells to which the majority of actively infected cells belong. These molecules may be identified with antibodies antibody fragments, or by the natural ligand for the cell-surface structures, e.g., by CD4 for gpl20 or by IL-2 for the IL-2 receptor. Details are described in Subheadings 1.1.1. and 1.1.2. 

In the current method, we demonstrate how aptamers selected against antigens on the cell surface or against the cell surface itself can be adapted to PLA for the sensitive detection of small numbers of tumor cells (Fig. 1). 

The products of the major histocompatibility locus have been shown to interact with viral antigens on the cell surface of thymocytes. A number of polypeptides bind to the major envelope glycoprotein of Rauscher murine leukaemia virus. The receptors for this glycoprotein, which probably involve lipoproteins, have been prepared from plasma membrane preparations from mouse cells. ... 

Although iVn and immunoglobulin coexist on the B cell membrane they are independent of one another. Anti-immunoglobulin antibodies cause the modulation of immunoglobulin surface antigens but not of /82m conversely, antibodies to /32m did not affect the expression of immunoglobulin antigens on the cell surface (295). 

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