Differences among available immunoglobulin preparations for intravenous use.

Today almost all IgG preparations for intravenous use (IVIG) fulfill the basic requirements for a preparation given intravenously (sterility, pyrogenicity, antibody content but also anticomplementary activity, etc.). However, there are still marked differences among such preparations caused by the method of preparation: (1) Enzymatically treated IVIGs (by pepsin and plasmin) have a shorter biologic half-time and a disturbed IgG subclass composition; (2) in chemically treated IVIGs (beta-propiolactone, reduced or sulfonated IgGs) the IgG3 subclass is lacking and some of the Fc-related functions are altered; and (3) the IVIGs purified by anion exchangers are poor in the IgG4 subclass. The three main preparations sold in the United States (Gamimune N, Gammagard and Sandoglobulin) belong to the nonmodified preparations and, with the exception of the IgG subclass representation, show similar Fab- and Fc-related properties (antibody content, interaction with Fc receptors on monocytes, phagocytosis-promoting activity, etc.) In none of these preparations, an elevated level of undesired contaminants (prekallikrein activator, irregular anti-erythrocyte antibodies) are found.

Cross comparison of the Limulus test between laboratories. Two European collaborative studies.

The results of two independent collaborative interlaboratory surveys evaluating limulus amebocyte lysate assays are presented. We investigated the variation of the results from laboratories all using the same reference endotoxin, but working with different gel-clot techniques. In the first study, four lysates were compared in quantitative gel-clot assays using either a macro- or a microtechnique. In the second study, the performance of a proposed limit test was checked under the auspices of the European Pharmacopoeia Commission. A generally good agreement was reached with the limit test; in the quantitative test, however, considerable interlaboratory variation and significant differences among the lysates were observed. In order to obtain consistent results, a thorough validation of all reagents and test parameters is essential. Collaborative studies are an important tool to detect discrepancies between laboratories and to decrease interlaboratory variability.

Quality control in the production of an immunoglobulin for intravenous use.

This paper briefly surveys the control measures and tests which are carried out before, during and after manufacture of an i.v. immunoglobulin in order to assure the quality of the preparation. The quality requirements are determined by both the standards expected by physicians and patients and by the specifications of the registration authorities in the various countries. A great deal of know-how and considerable technical investment is required to match these requirements. Furthermore a comprehensive quality assurance programme is compulsory: It begins with the careful collection and analysis of each single blood donation, continues through all the manufacturing stages and ends with the rigorous testing of every batch of the end product - an examination comprising 23 different tests.

Determination of the concentration of plasma proteins by density measurement.

Density measurement with a commercially available instrument (DMA 46, PAAR) was studied as an alternative method to the time-consuming and sometimes expensive methods currently in use for the determination of protein concentrations. The method is very useful for protein estimation in salt--and alcohol--free albumin bulk solutions and as an additional end product test for albumin and immunoglobulin solutions; it may also be used in the determination of total protein in plasma.

Assay of anticomplementary activity in solutions of immunoglobulins.

A method of estimating the inactivation of complement by immunoglobulins, based on a hemolytic assay, is described. During a three year period of routine assays the investigation of standard immunoglobulin solutions of high and low anticomplementary activity confirmed the reliability of the method. Since the activity of complement is largely dependent on the ionic strength, the salt concentration of the test solution must be carefully adjusted. The specific complement inactivation per gram immunoglobulin CI50/g is proposed as a parameter to compare the anticomplementary activity of immunoglobulin solutions.

Opsonic and physicochemical characteristics of intravenous immunoglobulin preparations.

The composition and opsonizing activity of five commercially available immunoglobulin preparations for intravenous use (Venoglobulin I, Venilon, Gammagard, Polyglobin, and Sandoglobulin) were studied. The composition of these preparations does not differ very much as far as total protein, immunoglobulin class and IgG subclass concentrations are concerned. The only exceptions were that Veniglobulin I, Gammagard and Sandoglobulin contain IgA, which might cause side effects in patients with anti-IgA antibodies, Gammagard contains very little IgG4, and Venilon and Polyglobin contain no and almost no IgG3, respectively, which might explain their very low opsonic activity. It was found that Venilon and Gammagard activate complement in the ready-for-infusion state. The opsonic activity of Venoglobulin I, Sandoglobulin and Gammagard is about equal to that of inactivated serum: Staphylococcus aureus, Escherichia coli with K antigen, Streptococcus pyogenes and Streptococcus group B are well opsonized and E. coli without K antigen and Streptococcus pneumoniae are poorly opsonized.

Immunoglobulin G subclass distribution in three human intravenous immunoglobulin preparations.

In immunodeficiency patients the lack of immunoglobulins (Ig) can be total or partial with a specific IgG subclass imbalance masked by normal values for total IgG. In the latter case therapy with intravenous IgG preparations (IVIG) is generally beneficial, provided the IVIG preparations used originate from large pools of normal blood donors and exhibit a normal IgG subclass distribution. We have analyzed the subclass distribution of three IVIG products: Sandoglobulin (SAGL), GamimuneN (GI), Gammagard (GG), 6-10 lots each, in four different laboratories. The competitive enzyme immunoassays and radial immunodiffusion methods used different monoclonal and polyclonal antibodies specific for IgG1, IgG2, IgG3, and IgG4, respectively. Despite minor interlaboratory differences, the results show that the slightly lower IgG1 content of SAGL versus GI and GG was quantitatively compensated by a higher proportion of IgG2, that no differences existed in IgG3 levels, but that one preparation (SAGL) contained 2-3% of IgG4 compared to 0.5-1.5% in GI and below 0.5% in GG. This difference was significant, the two latter preparations being at or below the lower limit of what are considered to be normal values found in human adults. Such differences may have important clinical consequences.