Effect of two cyclophosphamide derivatives on hemopoietic progenitor cells and pluripotential stem cells.

The studies described herein were undertaken to help define the effects of certain cyclophosphamide derivatives that have been used for selective removal of leukemic cells from marrow samples used for autologous transplantation. We have tested the effect of 4-HC and another cyclophosphamide congener, ASTA-Z 7557, on pluripotent stem cells (CFU-S) and committed progenitor cells (CFU-GM) in mice. The CFU-S were evaluated by the spleen colony assay at eight days and 12 days after transplant. The eight-day colonies are transient in nature, rapidly growing, mainly erythroid, and lack pluripotential precursors. The 12-day colonies are believed to provide a measure of hemopoietic stem cells as they slowly grow and do contain primitive precursors. Our data show that at the maximum dose levels tested, both drugs caused a 100% loss of CFU-GM and about 80%-95% inhibition of early transient CFU-S. In contrast, about 70% of the pluripotent 12-day CFU-S were spared. These data appear to explain the hemopoietic recovery seen in man after transplantation with marrow cells treated with 4-HC despite their relative absence of hemopoietic progenitor cells.

Immunologic recovery in thalassemic marrow graft recipients following high-dose busulfan and cyclophosphamide.

T lymphocyte subsets, mitogenic response, and immunoglobulin levels were studied in peripheral blood from 95 thalassemic patients before and at different times after bone marrow transplantation. With the exception of patients receiving more than 100 transfusion units before transplant, who showed an increased percentage of CD8-positive cells, thalassemic patients were essentially immunologically normal. Depressed lymphocyte proliferative response to phytohemagglutinin, concanavalin-A, and pokeweed mitogen; decreased IgG, IgM and IgA levels; and abnormal T subpopulation distribution were observed early after transplant. Long-term transplanted patients showed complete recovery of the immunological profile with the exception of the IgA levels, which were significantly decreased up to 2 years after transplant.

An attempt to obtain a specific antiserum for in vitro immunological conditioning of bone marrow in acute non-lymphoblastic leukemia.

An antiserum was produced in rabbits to acute undifferentiated leukemia (AUL) antigens. Partial absorption of the antiserum allowed the removal of the cytotoxic activity against normal mononuclear cells of peripheral blood and bone marrow, in contrast to blast cells from acute and chronic leukemias, which were killed by the antiserum in a standard NIH cytotoxicity test. These observations suggest that antigens present on blast cells of AUL are also expressed on some acute and chronic leukemic cells and that these antigens could be interpreted as B or leukemia-associated antigens because of the disappearance of all cytotoxic activity of the immune serum after extensive absorption with B cells from chronic lymphoid leukemia.

Fetal liver transplantation in the mini-pig.

After the characterisation of the hematological and immunological status of the mini-pig fetus at different gestational ages of development was performed, two different groups of animals receiving 800 rads of TBI given by a radioactive cobalt source at a dose/rate of 5/6 rad/min or 750 rads of TBI given by a Linear Accelerator at a dose/rate of 25/26 rad/min, both in a single dose exposure, were transplanted with a pool of allogeneic fetal liver cells whose age ranged between 55 and 75 days of gestation. In the first group 1 animal out of 6 is alive and well 30 months post-transplant. In the second group one of the nine transplanted animals survived 78 days. Engraftment was proved by the presence of the donor chromosome in the proliferating bone marrow cells in one animal.