A new Japanese regulatory perspective regarding the indication extrapolation between approved intravenous immunoglobulins (IVIg) products based on comparability assessments of quality attributes.

Anti-SARS-CoV-2 antibodies in healthy donor plasma pools and IVIG products—an update

Anti-SARS-CoV-2 antibodies in healthy donor plasma pools and IVIG products

Intravenous immunoglobulin products contain specific antibodies to recombinant human tau protein

ELISA measurement of specific antibodies to phosphorylated tau in intravenous immunoglobulin products

Anti-Fas antibodies in IVIG products and in healthy blood donors

Comparison of ELISA measurements of anti-Aβ concentrations and percentages of specific binding to Aβ between unfractionated intravenous immunoglobulin products and their purified anti-Aβ antibodies

The presence of anti-Rh D in intravenous immunoglobulin (IVIG) products has been claimed to be associated with adverse reactions in recipients. There is currently no regulatory specification to control the level of anti-D in IVIG products and it is unclear what this should be. Two reports of haemolysis occurring in recipients of IVIG manufactured from US plasma provided a rare opportunity to investigate whether high anti-D levels could have induced the haemolysis. We developed a direct microtitre plate haemagglutination method suitable for screening IVIG products and starting plasma pools for haemagglutinating activity. Of 101 batches of IVIG tested, six were found to contain specific anti-D. Four of these batches had anti-D titres ranging from 64 to 256 (including the two batches each associated with a report of haemolysis) and could be linked, in each case, to a starting plasma pool also positive for anti-D. Our results show that IVIG products can contain appreciable anti-D levels. To avoid potential problems in recipients, we propose an anti-D titre of 8 as the maximum permissible limit of anti-D in IVIG products for batch acceptance and release. The availability of a reference preparation is essential for control of this proposed requirement.

Specific binding of intravenous immunoglobulin products to tau peptide fragments.

Mechanisms of action of immune globulin

Correlation Between Clinical Response and Specific Antibody Levels in Patients Receiving IVIG for Humoral Immunodeficiency

The effects of intravenous immunoglobulin (IVIG) products were recently examined in patients with Alzheimer’s disease (AD). Although encouraging results were obtained in pilot studies, later trials produced negative results. The rationale for these studies was that IVIG contains antibodies to amyloid-beta (Aβ). However, if Aβ anti-idiotypic antibodies (antibodies which bind to anti-Aβ antibodies) are present in IVIG or induced by its administration, these antibodies could potentially reduce its neuroprotective effects in AD. The objective of this study was to determine if IVIG contained such antibodies. Enzyme-linked immunosorbent assays (ELISAs) measured specific binding of IVIG Gamunex to purified human anti-Aβ IgG. The mean concentration of its Aβ anti-idiotypic antibodies in four experiments was 1.85 μg/mL (18.5 μg/g IgG; range = 1.82–1.89 μg/mL [18.2–18.9 μg/g IgG]), and their mean percentage of specific binding was 72.2% (range = 68.3–75.3%). We then performed ELISAs to determine if antibodies to purified human anti-Aβ were produced in C57BL/6 mice injected with the IVIG product Gammagard in an earlier study. After subtracting the expected immune response to normal human immunoglobulins, the median concentrations of these antibodies were 15.6 ng/mL (range = 1.2–108.2 ng/mL) in pre-treatment sera and 2419.4 ng/mL (range = 327.4–8478.4 ng/mL) in post-treatment sera. These results indicate that specific Aβ anti-idiotypic antibodies are detectable in IVIG and may be induced in mice by its administration. The presence of Aβ anti-idiotypic antibodies in IVIG products might decrease neuroprotective effects of their anti-Aβ antibodies in AD.

All intravenous immunoglobulin (IVIG) products carry a boxed warning for the risks of renal dysfunction and thromboembolic events (TEEs). Patient-related thrombotic risk factors include hyperviscosity, a condition in which increased blood “thickness” heightens the risk of TEEs. Studies have shown that IVIG infusions increase plasma viscosity. To assess whether the viscosity of IVIG products themselves might be a parameter of interest in product selection, particularly for at-risk patients, we undertook an initial investigation into the viscosities of 5 commercially available 10% IVIG products. Experiments were performed using ALYGLO® [immune globulin intravenous, human-stwk 10% liquid], GC Biopharma; OCTAGAM® 10% [immune globulin intravenous (human) 10% liquid], Octapharma; GAMUNEX®-C [immune globulin injection (human), 10% caprylate/chromatography purified], Grifols Therapeutics LLC; PRIVIGEN® [immune globulin intravenous (human), 10% liquid], CSL Behring LLC; and GAMMAGARD LIQUID® [immune globulin infusion (human) 10%], Takeda Pharmaceuticals. IgG content was determined using the Lunatic system (Unchained Labs, USA). Samples were diluted with deionized water as necessary to normalize their concentrations for accurate viscosity comparison. Sample viscosities were determined using a Honeybun microvolume viscometer (Unchained Labs, USA) at 4, 10, 15, 20, and 25° C. Results were reported in centipoise (cP), a unit of measurement for a fluid’s resistance to flow, with a higher cP indicative of greater viscosity. The results at 25° C were as follows: ALYGLO: 2.506 cP; OCTAGAM: 3.484 cP; GAMUNEX-C: 2.535 cP; PRIVIGEN: 2.698 cP; and GAMMAGARD LIQUID: 2.575 cP. For reference, the viscosity of human plasma at 25° C generally ranges from 1.5-1.72 cP. All products showed consistent, sequential decreases in viscosity as temperatures increased, suggesting that IVIG infusions at room temperature (25°C) may be a safety consideration for the prevention of TEEs. These preliminary results warrant further investigation to identify potential differences in the viscosities of commercially available IVIG products, which may have implications for product selection in at-risk patients. Figure 1.

Measurement of isoagglutinins in immunoglobulins for intravenous application by flow cytometry

Intravenous immunoglobulin (IVIg) products from different pharmaceutical companies vary in composition, in part because of the selected blood donors and production process. N-glycosylation of the Fc-portion of IgG varies between blood donors and may influence both the side-effects and therapeutic effectiveness of IVIg. At present, the variation in Fc N-glycosylation between IVIg products has not been defined. Utilizing mass spectrometry, we performed relative quantitation of the Fc N-glycosylation of IgG, assessing a total of 154 unique lot numbers of IVIg. Seven products showed comparable Fc N-glycosylation, with only one product differing from the others in all glycosylation features (galactosylation, sialylation, fucosylation and bisecting N-acetylglucosamine). However, the mean difference did not exceed 3%. Within product variation was present to a minor degree, but largely indistinguishable from analytical variation. In conclusion, we expect that the minor variation in Fc N-glycosylation between IVIg products has a small effect, if any, on the biological activity.

BACKGROUND Cytomegalovirus hyperimmunoglobulin (CMV-HIG) preparations reduce mortality after solid organ transplantation. Polyspecific intravenous immunoglobulin (IVIg) products are also used prophylactically by some centers. Since direct comparative characterizations of the preparations are scarce, it is challenging to compare different clinical studies. MATERIAL AND METHODS The functionality of 2 CMV-HIG preparations (Cytotect® CP, Cytogam®) and 2 IVIg preparations (Ig Vena®, Flebogamma®) were compared in terms of: (i) CMV-specific immunoglobulin G (IgG) antibody levels determined by enzyme-linked immunoabsorbent assay (ELISA), (ii) avidity index using a CMV IgG avidity enzyme immunoassay, (iii) immunoblot assay against CMV-specific antigens, and (iv) anti-CMV microneutralization assay. RESULTS Median CMV-specific IgG antibody concentration was similar in the 2 CMV-HIG preparations (Cytotect® CP 101.8 PEIU/ml, Cytogam® 112.5 PEIU/ml) but markedly lower in the IVIg preparations (13.5 PEIU/ml and 21.3 PEIU/ml). CMV binding avidity was virtually identical for both CMV-HIG products (~90%). Immunoblot assay showed consistently high binding of both CMV-HIG preparations against all antigenic CMV glycoproteins tested. Recognition of some CMV-specific antigens (IE1, CM2, and p65) was weaker for the 2 IVIg products. Median CMV neutralizing antibody titers were identical for both CMV-HIG preparations (1:256), and 4-fold lower (1:64) for the IVIg products. CMV IgG antibody concentration correlated with the CMV neutralization titer. CONCLUSIONS Compared to the polyspecific IVIg products tested here, CMV-HIG preparations showed higher CMV binding activity and wider recognition of tested CMV-specific glycoprotein antigens, with markedly higher neutralizing activity. There do not appear to be any relevant distinctions between the Cytotect® CP and Cytogam® CMV-HIG products in terms of functional activity.