IVIG (intravenous immunoglobulin) is made by extracting antibodies from the pooled blood plasma of thousands of donors, then purifying and treating the product through multiple steps to make it safe for infusion. A single production batch typically combines plasma from 1,000 to 100,000 individual donors, and 10 to 40 separate donations go into just one treatment dose. The process from raw plasma to finished product takes several months and involves careful donor screening, protein separation, viral inactivation, and final formulation.
Plasma Collection and Donor Screening
The raw material for IVIG is human plasma, the liquid portion of blood that contains antibodies. Donors are screened and their plasma is tested for infectious diseases including HIV, hepatitis B, hepatitis C, and HTLV (a virus that affects white blood cells). The FDA requires both antibody-based blood tests and nucleic acid testing, which detects viral genetic material directly. Nucleic acid testing catches infections earlier than traditional antibody tests, since it can identify a virus before the donor’s immune system has produced a detectable response.
Plasma is collected through a process called plasmapheresis, where blood is drawn, the plasma is separated out, and the red blood cells are returned to the donor. Each donation is quarantined until test results are confirmed. Only plasma that passes every screening step enters the manufacturing pipeline.
Pooling Plasma From Thousands of Donors
Pooling plasma from a large number of donors is actually a key feature of the product, not a limitation. Because each donor carries antibodies shaped by their own immune history, combining plasma from thousands of people creates a broad spectrum of protective antibodies against many different infections and inflammatory triggers. A pool might include plasma from as few as 1,000 donors or as many as 100,000, depending on the manufacturer. This diversity is what makes IVIG therapeutically useful for patients with immune deficiencies or autoimmune conditions.
Cold Ethanol Fractionation
The core separation technique dates back to the 1940s, when Edwin Cohn developed a method for breaking plasma into its component proteins. The process works by gradually adding ethanol to chilled plasma, which causes different proteins to fall out of solution at different concentrations. Starting at about 8% ethanol and increasing to around 40%, the method yields five distinct protein fractions. The fraction rich in immunoglobulin G (IgG), the most abundant type of antibody in the blood, is collected and moved to the next stage. The basic principle is similar to refining crude oil: you’re separating a complex mixture into its useful parts.
Despite being decades old, cold ethanol fractionation remains the backbone of modern plasma processing. Manufacturers have refined the details, adjusting temperature, pH, and ethanol concentration to improve yield and purity, but the fundamental approach hasn’t changed.
Chromatography and Further Purification
After fractionation, the IgG-rich fraction still contains unwanted proteins and other contaminants. Manufacturers use chromatography, a technique that passes the solution through specially designed resins that selectively bind certain molecules. Ion-exchange chromatography is the most common method for immunoglobulin purification. It works by exploiting tiny differences in electrical charge between IgG and other proteins, allowing manufacturers to separate molecules that differ by as little as a single charged building block.
Most IVIG products are purified using anion-exchange chromatography with DEAE resins, which bind impurities while letting the IgG pass through (or vice versa, depending on the setup). Some manufacturers add additional chromatography steps or use different resin types to further improve purity. The goal is an end product that is overwhelmingly IgG with minimal contamination from other plasma proteins.
Viral Inactivation and Removal
Even with rigorous donor screening, manufacturers build in multiple layers of pathogen safety. Modern IVIG production includes at least two independent methods of killing or removing viruses, so that if one step misses something, the next one catches it.
Solvent-Detergent Treatment
This method uses chemical agents that dissolve the fatty outer envelope of viruses like HIV and hepatitis B. It’s highly effective against enveloped viruses but does not work against non-enveloped viruses, which lack that outer layer. The treatment requires an incubation period followed by removal of the chemical reagents from the product.
Pasteurization
Some products are heated to 60°C (140°F) for 10 hours in the presence of sugar-based stabilizers that protect the antibodies from heat damage while viruses are destroyed. Pasteurization works well against enveloped viruses but is less effective against non-enveloped viruses, which tend to be more heat-resistant.
Virus Filtration
The product is passed through filters with pore sizes as small as 15 to 35 nanometers. These filters physically remove viral particles based on size. A 35-nanometer filter can eliminate viruses larger than 40 nanometers (including HIV and several other pathogens) by a factor of over a million. Smaller, tougher viruses like parvovirus require a 15 or 20-nanometer filter for effective removal. This step catches pathogens that chemical treatments might miss, including non-enveloped viruses.
Combining these approaches creates what the industry calls “orthogonal” safety, meaning each method works through a completely different mechanism. Together, they reduce viral contamination to levels far below detection limits.
Final Formulation
Once purified and treated, the IgG concentrate is formulated into a product stable enough to store and safe enough to infuse. Most modern IVIG products are liquid formulations at a concentration of 10% (100 mg of IgG per milliliter), though some are available at 5%. The pH is adjusted to a mildly acidic range, typically between 4.0 and 5.0, because this is where IgG is most stable and least likely to clump together. Some older products have a more neutral pH (6.0 to 7.5), but the mildly acidic range better prevents protein aggregation.
Stabilizers are added to keep the antibodies intact during storage. The amino acid L-proline has emerged as a particularly effective stabilizer, reducing the formation of IgG clumps (called dimers) by up to 30% compared to the older standard, glycine. Dimers matter because they can trigger side effects during infusion. Some products use sugars like sucrose or sorbitol as stabilizers instead, though sucrose-containing products carry a higher risk of kidney-related side effects in certain patients.
The osmolality of the final product, which is a measure of how concentrated the dissolved particles are, varies widely between brands. Physiologic levels sit around 280 to 296 mOsm/kg, but some IVIG solutions exceed 1,000 mOsm/kg. Higher osmolality can contribute to headaches and other infusion-related side effects.
Quality Testing and Release
Before any batch reaches a patient, it undergoes extensive quality control testing. Manufacturers verify the IgG content, check for residual impurities, confirm that viral inactivation steps performed as expected, and test for bacterial contamination. The antibody composition is also evaluated to ensure the product contains a broad range of functional antibodies. Regulatory agencies like the FDA require that each lot meet strict specifications before it can be released for clinical use.
From plasma donation to finished product, the entire manufacturing process typically takes 7 to 12 months. This long timeline, combined with the sheer volume of plasma required, is a major reason IVIG remains one of the most expensive treatments in medicine and is periodically subject to supply shortages.