Factors Influencing Peripheral Blood Progenitor Cell Yield After 2nd Mobilization With G-CSF In Allogeneic Donors

Abstract

Purpose2nd collection of Peripheral Blood Progenitor Cells (PBPC) from the same donor is increasingly required for the treatment of complications after allogeneic transplantation, but information regarding the efficacy of this procedure is still limited. MethodsWithin our program 212 allogeneic donors underwent a 2nd cycle of G-CSF-application and PBPC leukapheresis between 1996 and 2012. Demographical data and details of donation are shown in table 1. G-CSF (lenograstim) was administered at a median daily dose of 7.5µg/kg for 4.5d; leukapheresis was performed on day 5 and 6, if necessary. Peripheral CD 34+ counts and leukapheresis yields after both mobilization cycles were compared. The influence of age, sex, BMI, G-CSF schedule and the interval between the donations on the efficacy of the 2nd PBPC mobilization were analyzed, too.Table 1Characteristics of PBPC donors with 2 mobilization cyclesGender145 male (68.4 %);67 female (31.6%)Age, years (mean, min-max)37 (1-70)Relationship to the recipient171 unrelated (80.7%)41 related (19.3%)Body Mass Index (mean, min-max)24.8 (17.2-43.2)Schedule of G-CSF-application29 single dose174 devided doseInterval between 1st and 2nd mobilization, months (mean, min-max)7.3 (0.6-105.0) ResultsMedian CD 34+ counts in peripheral blood were 53.2/µl at day 5 of 1st mobilization compared to 49.5/µl at day 5 of 2nd mobilization. Between 1st and 2nd donation, the median yield of CD 34+ cells/kg recipient b.w. decreased from 7.3 x 106 to 6.6 x 106 (p = 0.026, see table 2). The number of aphereses necessary in both donation episodes did not differ in the majority of donors (n=175; 82.5%). A strong correlation was observed between the amount of CD 34+ cells per recipient b.w. after the 1st and 2nd PBPC donation (r=0.89). The majority (65.4%, n=17) of donors with poor mobilization (<3 x 106 CD 34+ cells/kg recipient b.w.) after the 1st leukapheresis reached similar low CD 34+ counts after the 2nd mobilization. The interval between both mobilization cycles did not affect the results of the 2nd donation. According to an adjusted model, the other variables (age, sex, BMI and G-CSF-schedule) had no additional influence on mobilization efficacy in the 2nd cycle of G-CSF application.Table 2Comparison of the results of the first and second PBPC mobilization (median values and range)Parameter1stMobilization2ndMobilizationpCD 34+ concentration in peripheral blood on day 5 of G-CSF application53.2/µl (9-243)49.5/µl (6-207)0.099Yield of CD 34+ cells/ kg recipient weight (in 1 or 2 leukaphereses)7.3 x106 (1.3-68.6)6.6 x106 (0.9-65.1)0.026Donors with 2 leukaphereses60430.068 ConclusionsIn the largest group of healthy donors reported so far, we could demonstrate a slight reduction (about 10%) of PBPC yield after the 2nd mobilization that might not be clinically significant. Demographic variables affected the results of both mobilization episodes in the same way and the interval between them was of no significance. Our data support the assumption, that stem cell mobilization is probably determined by genetic factors and the outcome of a 2nd donation can easily be predicted by the results of the 1st one. Disclosures:No relevant conflicts of interest to declare.