A compliance/QA coordinator in New Mexico wonders what filters other institutions use when infusing peripheral blood stem cells (PBSCs). He wonders if it is sufficient to use a 'clot catching' (170-260 micron) filter, or if it is preferable to use an 80-120 micron filter during reinfusion. Does any institution use a 20-40 micron microaggregate filter or a 'third generation' leukocyte removal filter? The inquiring colleague has reviewed the following documents: the 3rd edition of the AABB Hematopoietic Progenitor Cell Standards, the 22nd edition of the AABB Standards for Blood Banks and Transfusion Services, and the Circular of Information for Cellular Products Therapy. Based on his review, he believes that one should avoid using leukocyte reduction filters when infusing PBSCs, but he is unclear as to which size screen filter is best suited for use with PBSC's, especially if one is concerned about large debris aggregates that might be present in PBSC products that have a volume of more than 30 mL. What do colleagues use for filtering PBSCs and do you worry about producing micro-pulmonary emboli during reinfusion of PBSC's?

The following response was received.

ADDENDA Dec. 17, 2003

1. A transfusion medicine physician at the Banco de Sangre de Cantabria in Spain reports that they infuse PBSCs through the standard red cell component filters. They have infused over 400 patients with more than 2000 bags of PBSCs using standard red cell component filters, and they have not found any adverse effects other than those that can be attributed to DMSO (as cryoprotectant they use the classical DMSO/ autologous plasma /ACD solution). They report having found no clots in their products, either in PBSCs or cryopreserved bone marrow. The responding physician comments that they have observed PBSCs from patients with myeloma or Waldestrom's disease develop white particles when the cryoprotectant agent is added. However, this has not had any influence on cell recovery after thawing, or adverse effects on the patient, as far as they know (and they control personally the infusion of every single bag). The responding colleague concludes saying that if you use leukocyte reduction filters, you will remove neutrophils and lymphocytes from the product, but many stem cells will also be lost, which will reduce the efficacy of the product.

2. A colleague in Sacramento reports that according to the joint AABB, ARC, and ABC "Circular of Information for the Use of Cellular Therapy Products", October 2003: "HPC products must NOT be administered through a leukocyte reduction or microaggregate filter. HPC products may be filtered through a 150-200 micron clot filter".

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator