A rapid and efficient method for the purification of the complement subcomponents C1r and C1s in zymogen form using fast protein chromatography

The purification of the subcomponents C1r and C1s of the first component of complement involves multiple steps and is time-consuming. This accounts for the frequently observed partial activation of the subcomponents. In this report we propose a simplified procedure of purification using a batch method and fast protein chromatography avoiding a shift of pH. The method provides C1r and C1s in a yield of 35 and 60% respectively. In addition, this study provides a simple and sensitive test to assess functional purity of C1r and C1s with respect to the other C1 subcomponents.     

Decay-accelerating factor in the cardiomyocytes of normal individuals and patients with myocardial infarction

Summary The presence of decay-accelerating factor (DAF) was clearly demonstrated on the surface of normal cardiomyocytes. In patients who had died of myocardial infarction (MI) cardiomyocytes displayed different appearances: outside the ischaemically damaged region the myocytes showed no significant variations in DAF expression when compared with controls without MI. Within myocardial zones damaged by ischaemia, however, apparently normal myocytes showed large gaps in surface staining of DAF or formed clusters which were entirely devoid of reactivity with anti-DAF antibodies. The number of DAF-deficient myocytes increased with the extent of necrosis and also with the number of days between onset of MI and death. Even though injury to myocytes is to a large extent related to anoxia and to the presence of free oxygen radicals, the complement system also appears to be involved; DAF may have protective functions against complement-mediated injury. We speculate that phospholipase may be involved in the removal of DAF from the cardiomyocyte surface.This work was supported in part by grant no. 3.157.88 from the Swiss National Foundation for Scientific Research and a contribution from Sandoz Ltd. Pharma Division, Basel     

Interaction of IgG and its fragments with red cells

The red cell uptake of ¹³¹I following incubation of red cells with [¹³¹I] IgG prepared from normal donors was shown to be IgG and not trace contaminants such as transferrin, lipids or iodide. The criteria used were immunodiffusion, DEAE chromatography, gel filtration and exchange with unlabelled lipoproteins and plasma. The uptake of [¹³¹I]IgG was pH and ionic strength dependent and was influenced by the proportion of cells to IgG present during the reaction. With constant cell concentration the uptake of [¹³¹I]IgG increased progressively as more IgG was added to the cells and approached an asymptotic value suggesting that there was saturation of red cell binding sites. When the IgG concentration was kept constant the uptake of IgG was inversely proportional to the red cell concentration. No difference in the molar binding of IgG, Fab or Fc was found indicating that the non-antibody binding of IgG does not preferentially involve any part of the IgG molecule. The molar quantities of carefully prepared [¹³¹I]IgG bound to red cells were similar to those obtained with [¹³¹I]BSA. The non-antibody red cell binding of IgG was contrasted with the antibody type of IgG binding.     

Mouse monoclonal antibodies at the red cell surface--I. Generation of EAC4 and interaction with C1

C1 and C1 activity measurements were performed with EA and EAC4 prepared with rabbit anti-Forssman IgG or IgM and were compared to measurements with EA and EAC4 prepared with mouse monoclonal IgG2b and IgM anti-DNP antibodies on cells coupled with TNP: the amount of TNP per cell was optimal for antibody activity. No differences were found in the ability of EAC4 made with poly- or monoclonal IgM to measure C1 activity; in contrast, monoclonal IgM was capable of activating only about 30% of C1 when compared to activation by polyclonal IgM. Monoclonal vs polyclonal IgGs behaved in a similar manner but they were detecting only 50% of C1 or C1 activity when compared to IgM of the appropriate class. It was concluded that monoclonal antibodies were capable of generating EAC4 intermediate, and that the ability of monoclonal antibodies in the EAC4 complex to bind C1 and to detect C1 activity is not significantly different from that of polyclonal antibodies but that monoclonal antibodies are less efficient in activating C1 than polyclonal antibodies.