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COBE® 2991 Cell Processing Procedure
Overview Video Automatic Processing Gain Control System
Step-by-Step Cell Processing Procedure

Whatever the application, almost all cell processing procedures on the COBE 2991 cell processor follow these basic steps:

  1. Install a cell processing disposable set.
  2. Connect the cell product bag and processing/washing solution containers to the cell processing disposable set. The starting cell product is prediluted, if necessary, and the cell processing bag is filled.
  3. Process the cell product either automatically or manually according to the desired protocol.
  4. Seal and remove the cell product bag.
  5. Remove the cell processing disposable set, including any waste fluids, and discard according to standard operating procedures.
Watch a Cell Processing Procedure from Start to Finish

Cell processing protocols typically include one or more cycles. Each cycle consists of three operations:

The operator may choose to run a protocol in either manual or automatic mode.

Manual processing: The operations are controlled by the operator; any operation can be skipped, or any one operation can be isolated.

Automatic processing: All operations are preprogrammed and automatically proceed in order of operation.

Automatic Processing

The example below illustrates how a cycle proceeds if automatic processing is selected. The cycle used in this example is based on a processing procedure for the washing of packed red blood cells (RBCs) to remove plasma. A COBE 2991 cell processing set (catalog number 90819) is the disposable set used for this procedure.

1. Start/Spin

The Start/Spin operation separates the starting cell product components into layers by spinning the centrifuge. Users control the separation by varying the spin time and centrifuge speed.

  • Cells with the highest specific gravity—RBCs—sediment to the outside of the cell processing bag
  • Cells with lower specific gravity (white blood cells and platelets, or buffy coat) sediment into a middle layer
  • Cells or fluids with the lowest specific gravity (plasma) collect toward the center of the processing bag

The COBE 2991 cell processor advances from the Start/Spin operation to the Supernatant-Out operation when the programmed spin time has elapsed.

2. Supernatant-Out

The Supernatant-Out operation expresses supernatant (plasma, in this example), or the product component layers with the lowest specific gravity, out of the cell processing bag.

The supernatant-out valve (SOV) opens and hydraulic fluid is pumped underneath the flexible diaphragm, which pushes against the bottom of the cell processing bag, expressing supernatant (plasma) out of the cell processing bag.

The presence of RBCs detected by the infrared sensor of the Red Cell Detector advances the COBE 2991 cell processor from the Supernatant-Out operation to the Agitate/Wash-In operation.

3. Agitate/Wash-In

The Agitate/Wash-In operation allows the cell product to mix with processing/washing solution.

The centrifuge decelerates to a near stop. The hydraulic pump reverses to its starting position. Processing/washing solution flows by gravity into the cell processing bag as the oscillating motion of the centrifuge causes the cell product and the processing/washing solution to mix.

Protocols that are programmed to finish after the Agitate/Wash-In operation leave the ending cell product resuspended in processing/washing solution.

Gain Control

Efficient and repeatable automatic cell processing procedures are just a protocol away. All COBE 2991 cell processors can process cell products automatically and are capable of storing 10 protocols, with the ability to use as many as seven cycles in each protocol.



Used to program up to seven cycles for each protocol. In Automatic mode, the cycle display indicates the current cycle.


Spin timer

Used to control the duration of the Start/Spin operation for each cycle, ranging from 00.0 minutes to 99.9 minutes.


Red cell override (R.C.O.)

Used to discard a volume of unwanted RBCs following cell detection based on the rate at which supernatant is expressed from the cell processing bag and the R.C.O. timer settings.


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