Plasma donation, known as source plasma, is a structured process where the liquid component of blood is collected for manufacturing life-saving therapeutics. These treatments include immunoglobulins for immune deficiencies, albumin for volume expansion, and clotting factors for hemophilia patients. Because these products are derived from human biological material, ensuring the safety of the plasma supply is the highest priority.
Plasma centers, particularly those in the United States, must adhere to stringent regulatory requirements established by the Food and Drug Administration (FDA). These federal mandates require comprehensive infectious disease screening of every donor and every unit of plasma collected before it can be processed into medicine.
The Standard Infectious Disease Screening Panel
The core of plasma safety relies on a standardized panel of infectious disease tests required for every donation. Federal regulations, outlined in the Code of Federal Regulations (21 CFR 601 and 610), mandate testing for agents transmissible through blood products. The primary focus is on viral pathogens that cause chronic infections and pose a significant risk to public health.
The screening panel explicitly targets the Human Immunodeficiency Virus (HIV), including both Type 1 and Type 2 strains. It also mandates testing for Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV), which can lead to chronic liver disease, cirrhosis, and liver cancer. Testing for these three viral agents often involves a dual approach, looking for both the virus’s genetic material and the antibodies the donor produces. For instance, Hepatitis B screening measures both the surface antigen (a marker of active infection) and core antibodies (evidence of past or current exposure). This comprehensive strategy ensures infections are caught regardless of the stage of disease progression.
The required panel also includes screening for Syphilis, caused by the bacterium Treponema pallidum. Although bacterial, Syphilis is efficiently transmissible through blood and is included in the mandatory donor screening. The inclusion of these four major infectious agents—HIV, HBV, HCV, and Syphilis—forms the basis of the mandated screening process.
The Testing and Screening Methodology
Infectious disease screening relies on highly sensitive laboratory techniques that work in tandem. One primary method is serological testing, often performed using technologies like the Enzyme-Linked Immunosorbent Assay (ELISA). Serology detects antibodies produced by the immune system in response to a pathogen, indicating that the donor has been exposed to the infection.
A more influential technique is Nucleic Acid Testing (NAT), which directly searches for the genetic material (DNA or RNA) of viruses like HIV, HBV, and HCV. NAT is particularly important because it significantly reduces the “window period,” which is the time between initial infection and when the body produces detectable antibodies. By identifying the virus’s genetic code, NAT can detect an infection much earlier than serology alone, adding an extra layer of safety.
Plasma centers often utilize NAT in a “pooled testing” format, where small samples from multiple donors are tested together for efficiency. If a pooled sample tests reactive, the laboratory then immediately performs individual NAT on each component sample to identify the specific unit that contains the virus. This multi-step, two-pronged testing system, utilizing both NAT and serology, is why plasma is held in quarantine immediately after donation. No unit of plasma is released for manufacturing until all required tests on the donor’s sample are confirmed as non-reactive.
Consequences of a Reactive Test Result
If any required screening test yields a reactive result, specific actions are immediately triggered concerning both the collected plasma unit and the donor. The plasma unit associated with the reactive test is immediately quarantined and must be destroyed, preventing its introduction into the manufacturing stream.
The donor is subject to a mandatory notification process, which includes informing them of the initial reactive screening result. This notification is always accompanied by a requirement for medical counseling and confirmatory testing, typically performed at a separate, certified laboratory. This ensures the donor receives appropriate medical information and follow-up care for a potentially serious infection.
A confirmed positive result for a disease like HIV, Hepatitis B, or Hepatitis C leads to an indefinite or permanent deferral from future plasma donation. Even a reactive result on the initial screening, if later confirmed negative, may result in a temporary deferral until subsequent testing confirms the donor is non-infectious. These deferral rules are a necessary measure to maintain the safety and integrity of the plasma supply chain.