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Variations in cord blood manufacturing and administration are common, and the optimal practice is not known. We compared processing and banking practices at 16 public cord blood banks (CBB) in the United States and assessed transplantation outcomes on 530 single umbilical cord blood (UCB) myeloablative transplantations for hematologic malignancies facilitated by these banks. UCB banking practices were separated into 3 mutually exclusive groups based on whether processing was automated or manual, units were plasma and red blood cell reduced, or buffy coat production method or plasma reduced. Compared with the automated processing system for units, the day 28 neutrophil recovery was significantly lower after transplantation of units that were manually processed and plasma reduced (red cell replete) (odds ratio, .19; P = .001) or plasma and red cell reduced (odds ratio, .54; P = .05). Day 100 survival did not differ by CBB. However, day 100 survival was better with units that were thawed with the dextran-albumin wash method compared with the “no wash” or “dilution only” techniques (odds ratio, 1.82; P = .04). In conclusion, CBB processing has no significant effect on early (day 100) survival despite differences in kinetics of neutrophil recovery.

A non-complement-binding monoclonal antibody, TAIL, recognizing determinants on human T lymphocytes, was linked to the plant seed toxin ricin, either the intact molecule or purified ricin A chain. Peripheral blood lymphocytes were pretreated with conjugate for 2 hr, washed, and then measured in vitro for T cell proliferation. Studies showed that antibody-intact ricin conjugates were up to 39-fold more inhibitory than antibody-A-chain conjugates. Killing was selective because an unreactive control antibody linked to toxin had minimal inhibitory effect. Dose response curves obtained in human studies were nearly identical to curves obtained in an animal model in which a monoclonal anti-murine T cell antibody (anti-Thy 1.1) was linked to ricin and ricin A chain. In the human system, longer exposures of peripheral blood cells to conjugates did not alter our findings.

A new antihuman T cell monoclonal antibody, MAb 22, recognizes an antigen that is present on all mature T cells, but detected on only a subset of thymocytes. Dual color flow microfluorimetery (FMF) demonstrates that MAb 22 staining has concordant distribution with pan-T MAb specific for CD3 and CD5 and includes the CD4 and CD8 subsets; other FMF studies confirm T cell specificity of MAb 22 expression by cells of hematopoietic origin. The antigen recognized by MAb 22 is expressed on only a subset of thymocytes and by dual FMF is expressed at a mature thymocyte stage. Immunoprecipitation by MAb 22 demonstrates a series of molecules with a predominant 45 KD protein and associated 12 and 95 KD proteins under reducing conditions, while a 92 KD protein predominates under nonreducing conditions. Comparisons of expression on a variety of T cell lines, including a mutant line defective in the expression of the T cell receptor, by FMF analysis further distinguishes the determinant recognized by MAb 22 from those detected by MAb of defined T cell specificity.

We report the development of a double-cycle elutriation (DCE) technique separating 3 or greater logs of T cells from a stem-cell-enriched marrow fraction and the results of phase I T-cell depletion studies with H LA-disparate related bone marrow transplantation (BMT) donors in two patient groups. In group 1,10 patients with refractory hematopoietic malignancies received combination chemotherapy, total body irradiation (TBI), and immunosuppression (pre-and post-BMT), and hematopoietic rescue with a marrow transplant, depleted of T cells by elutriation. Potentially to promote engraftment and a graft-versus-leukemia (GVL) effect, 0.5 to 0.75 × 105T cells/kg were added back. All 10 patients engrafted. Five patients developed acute graft-versus-host disease (GVHD; four grade II, one grade III) and two subsequently developed chronic GVHD. Two patients have relapsed (median follow-up, 206 days; range, 46 to 1,035). Four patients died of BMT-related complications (three of infection, one of veno-occlusive disease [VOD]). Four patient are disease-free survivors (median follow-up, 960 days; range, 670 to 1,035). Group 2 included five infants, four with congenital lymphohematopoietic deficiencies and one with refractory acute lymphocytic leukemia (ALL). In these infants, busulfan and increased cyclophosphamide were substituted for TBI. Only the ALL patient received added T cells. Three patients engrafted; one has stable mixed chimerism, one relapsed with ALL, and one rejected the marrow. One patient had primary autologous recovery, while another failed to engraft. None developed GVHD. We conclude that, in this setting of HLA-disparate BMT with post-BMT antithymocyte globulin (ATG) and corticosteroids, DCE significantly depletes T cells from the marrow and that a defined number of T cells can be added without the occurrence of severe GVHD.