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.

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.

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.

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.