Quantitative lymphocyte subset reconstitution after allogeneic hematopoietic transplantation from matched related donors with CD34(+) selected PBPC grafts, unselected PBPC grafts or BM grafts

CD34(+) cell selection of PBPC after harvest from G-CSF-treated allogeneic donors results in a more than 200-fold depletion of T lymphocytes in the gr aft and has been used to reduce the incidence of acute GVHD post transplant . Since transplantation with T cell-depleted BM grafts is associated with a delay in immune reconstitution and an increase of opportunistic infections , we evaluated the immunological reconstitution of patients with hematologi c malignancies after therapy followed by CD34(+)-selected PBPC34 transplant ation from matched related donors, Lymphocyte subset reconstitution over th e first 12 months post transplant and the incidence of infections were eval uated in 12 patients receiving PBPC34 grafts and compared to that of patien ts after transplantation with PBPC without CD34(+) enrichment (n = 20) or u nmanipulated bone marrow grafts (BM; n = 15), PBPC34 grafts contained 264-f old fewer T lymphocytes (median 0.53 x 10(6) kg/body weight) than PBPC graf ts and 36-fold fewer than BM grafts (140 x 10(6)/kg and 19 x 10(6)/kg, resp ectively). Despite a two log depletion of T cells in the PBPC34 grafts, T l ymphocyte reconstitution appeared comparable among the three transplant gro ups over the first 12 months. A positive patient CMV serostatus pretranspla nt was correlated with a faster T cell reconstitution in all transplant gro ups, GVHD prophylaxis with methylprednisolone delayed 15 lymphocyte reconst itution. The incidence of infections post transplant did not appear to be i ncreased in the PBPC34 group compared with the PBPC and BMT groups. It rema ins to be shown in larger prospective trials, whether these promising preli minary data of lymphocyte reconstitution and the clinical course after tran splantation with PBPC34 can be confirmed.