Erythrocytes sheep

Complement activity was first recognized by Bordet, who showed that the lytic activity of rabbit anti-sheep erythrocyte serum was lost on heating to 56°C but was restored by the addition of fiesh serum from an unimmunized rabbit. Thus, two faetors were necessary, a heat-stable factor, antibody, plus a heat-labile factor, complement, whieh is present in all sera. 

Among the several experimental models available to evaluate the involvement of the complement system [31], the measurement of hemoglobin released from antibody-coated sheep erythrocytes (CH50 test) is frequently selected because of its simplicity. Briefly, the lower the CH50, the higher the activation of the complement system. The CH50 test has been extensively used to compare NS-CA [32]. 

Immunological Effects. The effects of carbon tetrachloride on the immune system have not been evaluated in humans. Immune responses were not affected in rats orally exposed to carbon tetrachloride (Smialowicz et al. 1991). Parenteral exposure of animals to carbon tetrachloride has been reported to impair the immune system (Kaminski et al. 1989 Muro et al. 1990 Tajima et al. 1985), and oral exposure caused depletion of lymphocytes, hemorrhage, and hemosiderin deposition in the pancreaticoduodenal lymph node (Doi et al. 1991). These findings are supported by in vitro studies in which the IgM antibody formation response of isolated mouse splenocytes to sheep erythrocytes was inhibited in a dose-dependent manner when the splenocytes were exposed to carbon tetrachloride for 1-3 hours in the presence of cocultured hepatocytes (Kaminski and Stevens 1992). No effects were observed in the absence of cocultured hepatocytes. Mice appear to be more sensitive than rats to carbon tetrachloride-induced immunosuppression, but the biological significance to humans of these reported effects are yet ascertainable from the available data. 

Leukocyte migration inhibition. Ethanol (80%) extract of the dried rhizome, administered intragastrically to rats at a dose of 800 mg/kg, was active vs sheep erythrocyte-induced leucocyte migration " . 

Phenanthroline, on the other hand, stimulates the activity of some enzymes, perhaps by removing a metal that is inhibitory to the enzyme.523 524 It can induce porphyrin synthesis525 and improve the rate of ascorbate oxidation.526 It induces lysis of sensitized sheep erythrocytes.527 It is reported to reverse the resistance of microorganisms to penicillins.528 It binds to an immunoglobulin.529 It also protects rat liver from injury induced by dimethylnitrosamine530 and ethionine.531... 

Figure 31-9 Electron micrograph of a negatively stained sheep erythrocyte lysed with human complement. The cylindrical "attack complex" embedded in the membrane is seen in the upper left frame in side projection and in the lower frames in axial projection. The top views are of a proteolytically "stripped" ghost, the lower view from a freshly lysed ghost. The inner diameter of the cylinders is 10 nm scale bars 50 nm. From Bhakdi and Tranum-Jensen.169...

Figure 8.11 Electrophoretic mobility and zeta potentials of sheep erythrocyte. (Left) Relationship between true electrophoretic mobility in sheep erythrocyte and pH using NCE chips coated with BSA, gelatin, and MPC polymer. (Right) Relationship between sheep erythrocyte zeta potentials and pH using NCE chips coated with BSA, gelatin, and MPC polymer [39].

TCDD is a known immunosuppressant in animals in acute-, intermediate, and chronic-duration studies (Kerkvliet 1995). Suppression of the antibody response to sheep erythrocytes was observed in B6C3F1 mice administered 14 daily doses of 0.1 g 2,3,7,8-TCDD/kg/day (Holsapple et al. 1986), and a significant increase in mortality was observed in B6C3Fj mice administered 1.0 g/kg/day 2,3,7,8-TCDD for 14 days and challenged with Streptococcus pneumoniae (White et al. 1986). Decreased survival after viral infection was also reported in female B6C3F1 mice after a single intraperitoneal dose of 0.1 g... 

In an attempt to overcome this problem Kohler and Milstein (1975, 1976) have reported the results of fusing a mouse myeloma cell line with spleen cells taken from a mouse immunised with sheep erythrocytes. The hybrids were cloned and clones secreting anti-sheep erythrocyte antibodies selected. 

Sheep erythrocytes were purified and incubated in 50 pi PBS (8 g NaCI, 0.2 g KCI, 1.44 g Na2HP04, 0.24 g KH2P04 in 1 I H20). Erythrocytes were incubated for 15 min at 10°C together with up to 5 mM alkaloids. Then erythrocytes were precipitated by centrifugation (4 min at 2000 g), and the hemoglobin released from erythrocytes was determined photometrically at 543 nm.19... 

Complestatin (99) [84,85] was isolated from the mycelium of S. lavendulae and its structure was determined by NMR. It contains two unusual amino acids as shown in Fig. 16. The compound inhibits hemolysis of sensitized sheep erythrocytes mediated by guinea pig and human complement at concentrations of 0.4 and 0.7 ig/ml, respectively. 

Such relationships can be useful in designing synthetic membranes having properties similar to natural systems. For example, Equation 4 correlates the change in resistance caused by alcohols on potassium ion permeability of black lipid membrane (BLM) prepared from the lipid of sheep erythrocytes. The rather large negative intercept of Equation 4 indicates that three times the concentration of isolipophilic alcohol is needed to change the resistance of the BLM as is needed to cause hemolysis. Although the two processes are quite different, the role of hydrophobic forces in each can be compared. 

Casale, G.P., Cohen, S.D., DiCapua, R.A. (1983). The effects of organophosphate-induced cholinergic stimulation on the antibody response to sheep erythrocytes in inbred mice. Toxicol. Appl. Pharmacol. 68 198-205. 

The most active metabolite was the novel cyclic undecapeptide, cyclosporin A (Figure 8). As an antibiotic, cyclosporin A exhibited only a very narrow spectrum of modest antifungal activity, but in 1972 its true potential was realised. Jean Borel and colleagues at Sandoz discovered that cyclosporin A also neutralised cytotoxic T-cell activity in vitro and prevented haemagglutination in mice immunised against sheep erythrocytes. Further studies revealed that cyclosporin A inhibits T-cell proliferation by blocking the synthesis of IL-2. ... 

Modifications are made also in order to use this reaction to conjugate nucleosides to erythrocyte surfaces, allowing use of the coated cells as targets for assays of antibody-forming splenic lymphocytes. Nucleoside, 10-20 mg, is oxidized in 1.5 ml of 0.1 M sodium periodate in 0.15M NaHCOa for 20 min at room temperature the reaction is stopped by the addition of 15 /zl of ethylene glycol. Sheep erythrocytes are washed twice with 0.15 M NaHCOs, and 0.5 ml of packed cells is then suspended in 2.0 ml of the bicarbonate solution in a40-ml centrifuge tube. The oxidized nucleoside is added dropwise to the cell suspension and the mixture is kept at room temperature for 15 min. fert-Butylamine borane (Aldrich Chemical Co.), 100 mg in 5 ml of 0.15 M NaHCOs, is added. The suspension is kept at room temperature for 3 min, and the tube is then quickly filled with bicarbonate solution and centrifuged at 1500 rpm for 10 min. 

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