Priv.-Doz. Dr. Med. Jürgen Zingsem, Transfusionsmedizinische und Hämostaseologische Abteilung, Universitätsklinikum Erlangen, Krankenhausstr. 12, D-91054 Erlangen, Germany
Introduction: An increasing demand for blood components is opposed by a decreasing donor availability for the collection of the required blood components. Furthermore, current stem cell transplantation regiments require the collection of more than one similar or different component from one donor or patient. One strategy for maintaining the patients’ supply with the required blood components can be the concurrent collection of more than one component from one donor by apheresis, thus multicomponent apheresis.
Scope of multicomponent combinations: Combinations are possible for nearly every kind of blood components. In one session it is possible – depending on the apheresis device – to collect up to four plasma units alone, one or more plasma units and one or two red blood cell (RBC) units, one or more plasma units and one or more platelet units, one or more plasma units and one or two RBC units and one or more platelet units, one or two RBC units and one or more platelet units, two RBC units alone, one or more platelet units.
Also in leucocytapheresis the collection of more than one blood component has become a routine procedure. Performing allogeneic stem cell apheresis can lead to a cell dose for two transplantations or to one unit of PBSCs and concurrently collected and frozen mononuclear cells used for donor lymphocyte infusions therapy. Autologous mononuclear cell products (e.g. PBSCs or monocytes for dendritic cell generation) usually are cryoconserved before use and require additional plasmaproteins for cryoconservation. The latter can be obtained by the concurrent collection of plasma during leucocytapheresis. Thus, the combination of cell and plasma units or of cell units of different dose or for different purpose are further examples for the implementation of multicomponent apheresis in tumor therapy.
Conclusions: The understanding of apheresis technologies facilitates the use of multicomponent apheresis in the vast application field for tailoring the kind, quantity, and quality of blood components for patient care.
During the last years, requirements for blood components have increased continuously for different reasons. These are for example demographic factors like an increase in the average age of the population in most European countries and thus more older patients to be treated, more aggressive surgical procedures, and more aggressive and efficient cancer therapies. This increase is illustrated in the Paul Ehrlich Institute’s “Report on notifications pursuant to Section 21 German Transfusion Act for 2007”  showing that from 2003 to 2007, the production of blood components increased as follows: RBC units by 7·8%, platelet (PLT) units by 31·1% and fresh frozen plasma (FFP) units by 16·1%. On the other hand, the donor population is decreasing. Based on statistical data from 2004 that has been confirmed in 2009 , Greinacher et al. projected a decrease in blood donations by 27·5–32·6 percent to be expected in 2015 in comparison with 2004 . In addition, in most countries guidelines regularise a more and more restrictive donor selection for increasing the recipients’ safety. Unfortunately, these restrictions increase the donor deferral rates, too [5–7]. In addition to this rising imbalance between increasing need for blood components and decreasing donor availability, transfusion medicine services are also faced with economical pressures when providing blood components. On the one hand, costs for instruments, disposables, reagents, staff and additional donor testing rise continuously. On the other hand, financial resources in the health systems are limited so that the increase in costs cannot be passed on to the users or the reimbursement companies. For solving these problems, transfusion medicine services have been encouraged to advance the development and implementation of techniques enabling the concurrent collection of more than one single blood component during one donation from one donor, thus multicomponent collection.
Furthermore, it has been shown that cellular blood products prepared by apheresis are better standardized and often of higher quality than products prepared manually from whole blood [8–15].
Definition of multicomponent collection
Although there are definitions for multicomponent aphereses as procedures leading to at least two different blood components , most authors define a multicomponent apheresis as a procedure in which two or more identical or different blood components are collected [17–22]. This nomenclature will be maintained in this review.
Multicomponent collection techniques
For multicomponent collections, usually the same centrifugation techniques are used like those for the collection of each component alone. As extensive descriptions of the different apheresis systems have been provided in books and book chapters [23,24], this overview will be limited to a brief description of multicomponent collections which usually are performed automatically and in a standardized way using cell separators.
All cytapheresis systems are capable to produce up to three white cell poor platelet units either in the apheresis procedure [9–12,14,15,25–34] or through an additional filtration step [27,29–31]. Multicomponent apheresis procedures using these techniques enable the concurrent collection of up to three platelet units alone or in combination with fresh frozen plasma fulfilling all quality criteria without the need of further manipulations [21,35–39].
Furthermore, some devices are equipped with protocols for the collection of volume reduced PLT concentrates [40–44] which are not only adequate for intrauterine transfusion, but also permit the concurrent collection of larger plasma quantities.
As RBCs possess a significant higher density than plasma or platelets, they represent a distinct cellular component in the separation procedure when exposed to centrifugation force. This cell fraction can be collected alone or concurrently with PLTs and plasma [30,45–51]. The quality of the so collected PLTs and plasma is not impaired by the concurrent RBC collection, and the quality of the collected RBCs is superior to RBCs collected as whole blood donation [8,47,50–52], specifically because of the controlled mixing of the blood with the citrate and a well-defined haematocrit. The RBC apheresis techniques enable the collection of two RBC units in one procedure. On the one hand, this enlarges the flexibility in blood component production. On the other hand, the concurrent collection of two RBC units increases the risk of the donors’ iron depletion [53,54].
Besides the standard components like plasma, RBCs, and PLTs also different kinds of white blood cells (WBCs) are increasingly collected using techniques for obtaining more than one product during one procedure. As granulocytapheresis usually yields one single therapeutic dose, it shall not be discussed in this review. Other leucocytapheresis procedures, e.g. mononuclear cell collections, however, often are performed in a way to obtain more than one product. In recent years, stem cell transplantation is increasingly performed in terms of tandem transplantations [55–64]. Thus, stem cell apheresis is frequently performed with the objective of collecting two stem cell doses, thus two products within one apheresis procedure. Plasma needed for cryopreservation of the collected stem cells can be collected during the same procedure. In cases where more mononuclear cells are collected in one apheresis than required for one transplantation, the excess cells can be portioned into lymphocyte doses for further donor lymphocyte infusions.
Donor lymphocyte infusions for augmenting the graft-versus-tumor effect or for the treatment of leukemia relapse after haematopoietic stem cell transplantation is used increasingly [65–68]. These therapies usually require multiple injections of increasing numbers of mononuclear cells. Thus, lymphocytaphereses are performed in a way that results in multiple units of concentrated lymphocytes. The cells are partly diluted in concurrently collected donor plasma, portioned and cryopreserved.
The same approach is followed in the preparation of mononuclear cells for dendritic cell (DC) generation. After successful experiments in mice, manipulated DCs have been proposed as a “vaccine” to stimulate antitumor immunity [69–78]. For this therapeutical approach, important quantities of monocytes are usually required to get enough DCs for vaccination purposes. The plasma needed for the cell cultures  is concurrently collected with the mononuclear cells [79–83].
Thus, these collections of WBCs and plasma represent further applications of multicomponent collection.
No conflicts to declare.