[Application of a radial immunodiffusion technic in the determination of a specific immuneoserum titer]

One-step purification of rat plasma alpha 1-acid glycoprotein by antibody affinity chromatography: application to normal and inflamed rat sera

Most purification procedures used previously to isolate alpha 1-acid glycoprotein (AGP) from plasma can lead to some alterations in its carbohydrate moiety. An immunoaffinity chromatographic method is proposed for purifying in one step rat plasma AGP without any detectable modification of its glycan moiety. Crossed immunoaffinoelectrophoresis with concanavalin A before and after purification showed identical patterns, suggesting no glycan selection during the purification. In the same way no desialylation occurred during the purification step. This immunoaffinity chromatographic procedure provided evidence of a decreased level of fucosyl residues in turpentine oil rat plasma AGP compared with normal rat plasma AGP.

An immunochemical procedure to evaluate the degree of desialylation of alpha 1-acid glycoprotein in rat serum

When radial immunodiffusion (RID) and electroimmunodiffusion (EID) were used for the determination of rat alpha 1-acid glycoprotein (alpha 1-AGP) a significant discrepancy in the results was encountered depending on the degree of sialylation. When alpha 1-AGP was desialylated, the amounts estimated by EID were much lower than those actually present as assayed by the RID method. The relationship between the percentage of desialylation of alpha 1-AGP and the percentage of its underestimation by EID relative to RID was determined and a calibration curve was plotted to evaluate the degree of desialylation of rat alpha 1-AGP. When compared to other procedures (rat membrane inhibition assay and isoelectrofocusing), the proposed method was easier to perform and allowed the specific evaluation of the degree of undersialylation of the glycoprotein.

[Laurell electroimmunodiffusion. Concerns and limits of various technics for the study of immunoaffinity chromatographic eluants]

Monodimensional and bidimensional electroimmunodifusion techniques were applied to the study of immunochromatography eluates. They were obtained with human sera as samples, and rabbit anti human sera alpha1AGP antibodies coupled to CNBr Sepharose 4B packed in a chromatography column. By monodimensional electroimmunodiffusion alpha1AGP could be quantitated. By tandem bidimensional immunoelectrophoresis the eluate purity could be shown, as well as its identity to alpha1AGP. Besides, this last technique was used to the critical study of elution conditions, and to put forward the influence of some parameters (such as pH ionic strength) on alpha1AGP denaturation and its transformation into a protein which is still antigenic but has lost a part of its electrophoretic mobility at pH 8.6. This phenomenon could explain the alpha1AGP loss observed after column elution. The precautions in the interpretation, the interest and the sensitiveness of the electroimmunodiffusion techniques are exposed.