The degradation of red cell stroma phospholipids by phospholipase A2 is accompanied by a concomitant fall in the activity of the Rh antigens, c, D and e. The action of phospholipase C on stroma also brings about a fall in D antigen activity. Anti-D bound to the red cells protects the D antigen from inactivation by phospholipase A2.

No abstract

An analysis of the assay of 28 preparations of anti-D immunoglobulin using a radioisotope method carried out at 6-monthly intervals for 2-4.5 years showed an average fall in anti-D concentration ot 10.6% each year, with 99% confidence limits ot 6.8-14.7%. The fall in anti-D concentration after storage at 37°C for 1 month was less than 8%, the minimum change that could be detected. No significant change in physical characteristics of the immunoglobulin were detected. The error of a single estimate of anti-D by the radioisotope method (125I-labelled anti-IgG) used here was calculated to be such that the true value probably (p=0.95) lay between 66 and 150% of the estimated value.

The HI technique used in this study has been described in detail elsewhere (Gust, 1973). Briefly, the test involved the treatment of sera with either kaolin or heparin-manganous chloride to remove nonspecific inhibitors, followed by adsorption with 50% pigeon erythrocytes. Doubling dilutions of the treated sera were incubated with 6 to 8 haemagglutinating doses of rubella antigen and 0-2 % pigeon erythrocytes.PHA TEST PHA antibodies were detected using a commercially available test kit (Rubacell, Abbott Laboratories, Chicago, Illinois). Stabilised human erythrocytes, sensitised with rubella-virus soluble antigen, were reacted with untreated human sera for determination of antibody levels. The exact procedure followed was according to the manufacturer's instructions except 128 on 11 May 2018 by guest. Protected by copyright.

Abstract. Two methods are described for the estimation of anti‐D activity in immunoglobulin preparations which are based on the radioimmunoassay inhibition techniques. In one of the methods, estimates were made under equilibrium conditions in a solution of normal ionic strengh. In this method, the assay is affected both by the concentration of the anti‐D and the value of its equilibrium constant. This method did not correlate well with the standard assay method using 125I‐labelled anti‐IgG. In the second method, conditions were modified so that measurements were made at non‐equilibrium conditions and in a solution of low ionic strength. Under these conditions, the assay is mainly dependent on concentration of anti‐D, although it is influenced by the rate of association of anti‐D with red cells. The second method correlated well in 24 out of 27 instances with the concentration of anti‐D measured by the method using 125I‐labelled anti‐IgG.