Complement-fixing antibodies

Hemolysis Alteration, dissolution, or destruction or red blood cells in such a manner that hemoglobin is liberated into a medium in which the cells are suspended (e.g., by specific complement-fixing antibodies, toxins, various chemical agents, tonicity, alteration of temperature. 

Type II Drugs often modify host proteins, thereby eliciting antibody responses to the modified protein. These allergic responses involve IgG or IgM in which the antibody becomes fixed to a host cell, which is then subject to complement-dependent lysis or to antibody-dependent cellular cytotoxicity. 

R16. Rothfield, N. F., and Stollar, B. D., The relation of immunoglobulin class, pattern of anti-nuclear antibody, and complement-fixing antibodies to DNA in sera from patients with systemic lupus erythematosus. J. Clin. Invest. 46, 1785-1794 (1967). 

Complement-fixing properties Reactivity with cellular receptors Degree of lattice formation Size of the complex Solubility properties Complement-fixing properties Clearance and distribution properties Rate of formation Antigen availability Antibody synthetic rate Rate of clearance... 

In spite of the strong evidence for the role of DNA/anti-DNA complexes in causing the kidney lesions of systemic lupus (A6, K13, K15, W19), it is not certain that the material assayed in serum as immune complexes is actually composed of DNA linked to specific antibody. Several groups have demonstrated DNA (D2) or anti-DNA (H10) in immune complex material from sera, but careful studies by others have failed to repeat these findings (A7, H27, 18). DNA, by itself, does not persist in the circulation (G10, 17). Because of the multiplicity of autoantibodies found in lupus, any of a number of antigen-antibody systems may be involved (T4). Based on direct examination and the reactivity patterns with various immune complex assays, the immune complex material found in systemic lupus tends to be macromole-cular (>19 S) and complement fixing (A5, A7, C5, D2, El, F12, Gl, L2, M10, N6, T15). 

The complement system is a series of approximately 30 serum proteins that promote the inflammatory response. In complement-dependent responses, after IgG antibodies bind to the cell-surface antigens, complement fixes to complement receptors... 

Failure of intrinsic factor secretion is commonly a result of autoimmune disease 90% of patients with pernicious anemia have complement-fixing antibodies in the cytosol of the gastric parietal cells. Similar autoantibodies are found in 30% of the relatives of pernicious anemia patients, suggesting that there is a genetic basis for the condition. 

Fig. 6. Binding of I-labeled protein A (PA) (0.1 ml 26,0(X) cpm added) to 10 line-10 (L-10) tumor cells sensitized with increasing amounts of rabbit antiserum to line-10 cells ( — ) or to the antigenically distinct line-1 (L-1) (O—O). These determinations of total bound IgG are compared to the cytotoxic (complement-fixing) activity of the antisera. Cytotoxicity was measured as uptake of the vital dye trypan blue following incubation of the antiline-10 (A—A) or anti-line-1 (A—A) sensitized line-10 cells with human complement. A relative concentration of 1 corresponds to a si dilution of antibody. From data given in Lan-gone et al. ...

ACAID Anterior chamber-associated immune deviation-a unique form of immune tolerance. ACAID is a selective, systemic immune deficiency where Antigen-specific delayed hypersensitivity and complement-fixing antibody responses are impaired by lymphocyte responses while other immune effectors are left preserved. 

A complement-fixing antibody in the serum of pernicious anemia patients, diabetics, and those widi iron-deficiency anemia has been detected against mucosal extracts of the fundus and body of the hmnan stomach and the microsomal fraction of gastric mucosal extracts (D8, 14, M8, M48, RIO, TI3). Immunofluorescent studies have shown that activity is directed against gastric parietal cell cytoplasm (15, RIO, T13) and probably represents another type of antibody, which develops about twice as frequently as the one directed against intrinsic factor in pernicious anemia serum (Fig. 27). 

The complement-fixation assay depends on the fact that during the reaction of an antibody with its antigen, added complement is also fixed. The amount of complement fixed is directly proportional to the quantity of antigen which has reacted with the antibody, and therefore, in the presence of an excess of the latter, it is directly proportional to the quantity of antigen added. Another immunological system is... 

IgA system is our latest and most sophisticated evolution. It provides a stable complement-fixing lethal antibody outside the body, of which only trace amounts ever seem to leak back (T6), and a 7 S noncomplementfixing information system on the inside. In contrast IgM and IgG can be lethal, but can also backfire by fixing complement within us. The role of serum 7 S IgA still awaits complete understanding, but it is known to provide the chief defense mechanism against certain viruses (T7). 

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