PBPC collection techniques: standard versus large volume leukapheresis (LVL) in donors and in patients.

Transplantations of autologous and allogeneic peripheral blood progenitor cells (PBPC) are able to assure a complete hematopoietic and immunologic reconstitution in patients. PBPC are collected by leukapheresis technique after prior mobilization therapy, but procedures and results remain still highly variable and are poorly characterized. An optimum regimen for PBPC collections has not yet been recommended, but 2-3 total blood volumes (TBV) of the donor or patient are regarded as a standard. Another promising technique is large volume leukapheresis (LVL) with processing of 3-6 TBV of donor or patient. The aim of this paper is to find the most efficient and safe collection technique for an individual donor or patient and, consequently minimize the number of procedures required. Finding the optimal collection procedure would be helpful while considering which method would be preferred in an individual donor or patient with respect to the result of mobilization, health state and required yield of CD 34+ cells for transplantation. We evaluated the results in a total of 134 standard and LVL procedures, which were performed in 21 well mobilized donors (Group I), in 65 well mobilized patients (Group II), and in 14 weakly mobilized patients (Group III) with hemato-oncological diseases. A precollection concentration of CD 34+ cells in peripheral blood higher than 20 x 10(3)/mL was considered to be the criterion for efficient mobilization. Such levels of concentration indicating the start of PBPC collections could be easily reached in Group I of donors and Group II of well mobilized patients. Heavily pretreated patients at advanced stages of disease (Group III) did not respond to mobilization sufficiently and had a concentration of CD 34+ cells lower than 20x10(3)/mL. LVL technique made it possible to obtain higher numbers of CD 34+ cells than in the standard collection in well mobilized donors (Group I), well mobilized patients (Group II), and even in weakly mobilized patients in Group III. In donors and well mobilized patients (Group I and Group II) it was possible to collect sufficient amounts of CD 34+ cells for allogeneic or for autologous transplantation from one LVL collection. The median yield of CD 34+ cells from one LVL collection was 5.5 x 10(6)/kg b.w. in donors, and 6.0 x 10(6)/kg b.w. in well mobilized patients. Due to the linear dependence of the yield of collected CD 34+ cells on the concentration of CD 34+ cells in blood, it can be used as a simple prediction of the success of collection in Group II (correlation coefficient 0.93 for standard procedures, and correlation coefficient 0.88 for LVL). In Group III of weakly mobilized patients the standard collections were usually ineffective and the relationship between the yield of CD 34+ cells/kg in the product and the precollection concentration of CD 34+ cells was much less significant (correlation coefficient 0.56 for standard procedures and correlation coefficient 0.66 for LVL). The median of CD 34+ cells collected from one standard procedure was only 0.7 x 10(6)/kg but using LVL the median increased to 1.4 x 10(6)/kg. Our results prove that the yield of CD 34+ cells in the product can be enhanced by large volume leukapheresis (LVL). Based on the results obtained, we recommend LVL in all donors and patients who can tolerate it due to a greater chance of collecting higher yields of progenitor cells while minimizing adverse reactions. LVL procedures should also be preferred in weakly mobilized patients where it is not possible to collect sufficient amounts of CD 34+ cells for transplantation using the standard regime. In weakly mobilized patients LVL provides a greater chance to at least collect a minimum amount of CD 34+ cells necessary. LVL should be used in circumstances where extremely high doses of CD 34+ cells has to be prepared, e.g. planned "tandem" transplantations or manipulations with a graft in which a significant loss of cells is expected.