Leukopak

What is a Leukopak?

A leukopak is an enriched apheresis product collected via leukapheresis, the act of extracting white blood cells (WBCs) from the peripheral blood. Leukopaks contain a high concentration of mononuclear cells (PBMCs) – which consists of T cells, B cells, NK cells, and monocytes. As shown below, WBC concentration is significantly higher in a leukopak (mean of 38.48 x 10⁶ WBCs/mL) than whole blood (mean of 6.48 x 10⁶ WBCs/mL). Additionally, red blood cell (RBC) concentration is significantly lower in a leukopak with a mean of 0.43 WBC for every RBC (about 1 WBC for every 2 RBC), whereas in a whole blood unit, it is a mean of 0.001 WBC for every RBC (about 1 WBC for every 1,000 RBCs). Similarly, leukopak purity and quality when compared to a buffy coat is far superior typically containing 20 times higher mononuclear cell content. PBMCs are highly prized for their use in immunotherapy research, cell therapy process development, and clinically. Therefore, leukopaks have become the starting material of choice for cell therapy research and drug development.

White Blood Cell Concentration	White Blood Cell to Red Blood Cell Ratio

Leukopaks are collected at HemaCare’s FDA-registered collection center from healthy human donors who have consented under an IRB-approved protocol. This mononuclear cell-rich leukapheresis product is extracted using continuous flow centrifugal technology (Spectra Optia® apheresis system) directly into a sterile collection bag containing ACD-A anticoagulant with IQ, OQ, and PQ specifications.

Leukopaks play a critical role in the discovery, development, and manufacture of life-saving therapies. HemaCare can support your project from research through commercialization. When buying leukopaks, we suggest you review the different options below to decide which leukopak type is best for your research: fresh or cryopreserved research use (HemaPrime™) or GMP-compliant (GMPrime™) leukopaks.

High-Quality Leukopaks

A high-quality leukopak is a perfect balance of purity and yield. Achieving this balance requires not only apheresis expertise, but also a commitment to donor management. With donor nurturing and dietary guidance, we can maximize the potential quality of leukopaks from donors. However, even high-quality leukopaks are variable in terms of yield. Donor-to-donor variability is inherent and often unpredictable. This natural variability, however, will definitely be present in a patient population and must be accepted and accounted for during process development. Figure A demonstrates this natural variability across a sampling of 2,490 donors collected by HemaCare in our donor facility. The mean WBC yield of this analysis is 12.7 x 10⁹ cells/donor, but the distribution of normal WBC yield is quite broad.

Figure A	Figure B

Although donor-to-donor variability certainly exists, with proper training, adherence to best practices, and standardization, collection-to-collection variability can be minimized. One strategy to minimize variability for certain applications is to utilize recallable donors. Figure B demonstrates the relative consistency of CD4⁺ cellular populations collected from recallable, reliable donors at multiple timepoints.

To gain a better understanding of the amount of variability apheresis centers encounter on a regular basis, review our in-depth analysis of a representative sample of our fresh leukopak collections drawn from healthy donors.

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A Cryopreserved Leukopak for Every Stage of Research

Depending on your stage of discovery, you may have specific considerations which affect the type and specifications of the leukopak needed. For early stages, maximum recovery of specific cellular components is of primary concern. The presence of granulocytes can negatively impact the consistent recovery of cells of interest within a cryopreserved leukopak as well as the stability and functionality of those cellular subcomponents. Granulocytes are poorly cryopreserved and can release DNA and lysosomal enzymes after freezing and thawing leading to clumping and loss of cell viability. Granulocyte contamination has been associated with the reduction of cell counts within MNCs, inhibition of T cell proliferation and activation, as well as the loss of regulatory T cells integrity. Controlling granulocyte contamination during apheresis collection and cryopreservation is critical in ensuring a consistent, stable, and functional leukopak.

Conversely, later stages of development require that materials be truly indicative of the population as a whole as these process development steps will ultimately be translated to the clinic and to patients. Testing must take into account variability as patient material will be highly variable. Therefore, for these later stages of development, a product which is uncontrolled for variability may be the most desirable.

Do you require consistency or variability in your cryopreserved leukopak?

Shop HemaPrime Cryopreserved Leukopak

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