Over the immediate past 4 years, our program has collected hematopoietic progenitor cells by apheresis from 48 individuals aged 61 and over (range 61-71 years of age). We have retrospectively analyzed the collection and transplant results associated with employing these donors, and have compared them with 175 donors aged 60 or less who were collected during the same time period. We have found no significant difference in venous access (P ¼ 0.208), rate of post-transplant engraftment of neutrophils (P ¼ 0.117) and platelets (P ¼ 0.692), or in rate and grade of acute GVHD (P ¼ 0.806). However, we have found that these older donors have a significantly lower mobilization of CD34 þ cells as reflected in lower absolute counts of circulating CD34 þ cells preapheresis (P ¼ 0.016). This, in turn, results in lower CD34 þ cell yields in apheresis products (Po0.001), trending towards requiring more apheresis procedures (22.9 vs 13.7%, P ¼ 0.095) to collect sufficient CD34 þ cells for transplantation. We conclude that it is practical when necessary to employ donors aged 60 and above, as well as safe for both donor and intended recipient. However, concern over reduced CD34 þ cell mobilization may be sufficient grounds to seek younger donors when possible.

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4226 There has been reluctance to collect apheresis HPC grafts from donors of age 60 and beyond. This is predicated on concern over relative frailty, poor venous access, reduced potential for HPC mobilization, and reduced potential for stable engraftment of HPC transplant. We have expanded our transplant eligibility into patients beyond the age of 60, with the concomitant acceptance of matched sibling donors of similar age. We have reviewed 96 consecutive sibling donors, 19 of whom were of age ≥60 years at the time of collection. All donors were collected using Gambro Spectra apheresis instruments, and the volume of blood pheresed was gauged to target a CD34 dose of 5-10 million per Kg of recipient weight. We have found the following: Age < 60 (n=77) Age ≥ 60 (n=19) p Blood volumes (Mean±Std) 4.9±3.3 6.1±3.1 .85 CD34/RecipKg E6 (Mean±Std) 8.1±2.8 5.8±1.7 .02 CD34/Blood vol E7. (Mean±Std) 18.0±11.7 10.9±7.8 .06 < 5E6 CD34/Kg Collected (n) 5 3 .21 > 1 collection (n) 12 7 .04 Catheter required (n) 23 6 .54 Grade 3+ pheresis complications 2 3 .47 ANC500 Median days (Min-Max) 16 (10-28) 16 (13-75) .14 Plt20K Median days (Min-Max) 16 (8-77) 16 (13-89) .30 These results suggest that donors of age ≥60 years may be successfully collected, and that the resultant grafts can be expected to produce successful transplants. There is not a higher toxicity rate or need for catheter insertion associated with the collections in the older age group. There is a clear trend, however, to reduced mobilization of CD34+ cells, as reflected in the need for more collections, and fewer CD34+ cells per blood volume leukopheresed. In spite of this, sufficient cells to produce functional grafts were collected from all donors, although a limited number of donors in both age categories failed to collect a full 5e+6 CD34/Kg. We conclude that in the context of an aging demographic, allograft donors of age ≥60 may be successfully employed for HPC collection. Further, we propose that the application of plerixafor in ≥60 year old donors should be investigated in the context of a growing need to collect allografts from donors in this age group. Disclosures: Off Label Use: sirolimus for graft-versus-host disease.