Search

Highly purified CD34++CD38−Lin− hematopoietic progenitors isolated from human fetal liver were infected with the murine retroviral vector, MFG nls-LacZ, which encodes a modified version of the Escherichia coli β-galactosidase gene. Progenitors that were cocultured with the packaging cell line could reconstitute human bone marrow or thymus implanted in SCID-hu mice. Expression of the β-galactosidase gene was observed in primitive and committed clonogenic progenitors, mature myeloid, B-lineage cells, and T-lineage cells for up to 4 months after injection into SCID-hu mice. Furthermore, hematopoietic reconstitution by genetically modified progenitor cells could be achieved by the injection of the cells generated from as few as 500 CD34++CD38−Lin− cells, suggesting efficient retroviral gene transfer into fetal liver progenitors.

CD28 is a cell surface molecule present on most peripheral T cells which has been implied in the amplification of the T-cell response in vitro. Using in situ hybridization on human prometaphase cells, we have found that the human CD28 gene maps to chromosome 2 at bands q33–q34, as shown previously for the CTLA-4 gene. CD28 and CTLA-4 are both members of the Ig superfamily, where they define a subgroup of membrane-bound single V domains. Their chromosomal proximity and their close structural relationship suggest that these two genes could be the result of the duplication of a common evolutionary precursor and may share some functional properties.

The c-fmsprotooncogene product was identified as the CSF-1 or M-CSF receptor, a polypeptide growth factor that plays a major role in myelomonocytic differentiation. This led us to look for expression of c-fmsin fresh acute myeloid leukemia (AML) cells, using Northern blot analysis. c-fmsexpression was found in the leukemic cells of 28 AML patients, regardless of their stage of differentiation, which was assessed in the French-American-British (FAB) classification. However, the level of c-fmsexpression was espe- cially high in AML of the M5 stage. High levels of expression were not accompanied by either amplification or rearrangements of the c-fms gene in AML cell DNAs. In contrast, c-fms expression was not found in acute lymphoid leukemias, whether of T or B origin. Thus, c-fms expression appears as a specific molecular marker of leukemogenesis in the myeloid lineage.1988 by Grune & Stratton, Inc. 0006-4971/88/7203-0045$3.00/0

Surface immunoglobulins (sIg) were detected on human lymphocytes by immunoelectron microscopy with peroxidase-conjugated antibodies. Blood, marrow, and thymus cells from normal individuals and patients with lymphoproliferative disorders were examined. Samples were fixed before exposure to specific reagents. Normal lymphocyts with detectable sIg, i.e. B lymphocytes, were characterized by a villous surface; nonlabeled blood lymphocytes and thymocytes were smooth cells. Intermediate cells were also found which in sections appeared moderately villous and labeled, thus identified as B lymphocytes. Further evidence for a relationship between villous surface and sIg was given by the finding of a few lymphocytes with polar concentration of labeled microvilli. In chronic lymphocytic leukemia patients, most cells exhibited a villous surface with parallel variations of the number of microvilli and of anti-immunoglobulin-binding capacity. However, some labeled smooth blastic cells were also observed. On the other hand, abnormal lymphocytes from Sézary's syndrome which could exhibit segments of villous membrane had no detectable sIg. This study confirms that in most cases human B lymphocytes have a characteristic surface appearance and that the detection of sIg in normal lymphocytes correlates with the presence of microvilli.

A new in vitro immunophysical method of removing leukemia or lymphoma cells from autologous bone marrow is described. This new technique makes use of low-density polypropylene beads (density: 0.91) coated with a monoclonal antibody anti-CALLA (antibody ALB2).

We evaluated serially by cytogenetics the blood and marrow chimerism of 38 leukemic recipients of HLA-matched bone marrow transplants (BMT) who were prepared by high doses of alkylating agents and fractionated total-body irradiation (2.2 Gy x 5). Donor or host mitoses were identifled by examination of sex chromosomes in 32 patients or by evaluation of the polymorphism of other chromosomes after specific banding in six patients. Twenty-four patients were recipients of untreated BMT. and 1 4 were recipients of T-cell-depleted BMT. In the 24 patients who received untreated BMT. all showed successful engraftment. and only three had a transient mixed chimera. In the 14 recipients of T-cell-depleted BMTs. four rejected their grafts. and seven had mixed chimeras; these mixed chimeras were more frequent in blood lymphocytes than in marrow cells and could be detected up to 26 months after BMT. This high frequency of partial chimerism after Tcell- depleted BMT by comparison with a control group suggests that the donor’s T cells play an important role in the eradication of host residual hematopoiesis after allogeneic BMT.

A patient with primary plasma cell leukemia resistant to chemotherapy was treated for 2 months with daily intravenous injections of anti-interleukin-6 (IL-6) monoclonal antibodies (MoAbs). The patient‘s clinical status improved throughout the treatment and no major side effects were observed. Serial monitoring showed blockage of the myeloma cell proliferation in the bone marrow (from 4.5% to 0% myeloma cells in the S-phase in vivo) as well as reduction in the serum calcium, serum monoclonal IgG, and the serum C-reactive protein levels. The serum calcium and serum monoclonal IgG corrected by approximately 30%, whereas the C-reactive protein corrected to undetectable levels during treatment. No major side effects developed, although both platelet and circulating neutrophil counts decreased during anti-IL-6 therapy. A transient immunization was detected 15 days after the initiation of the treatment, which could explain the recovery of myeloma cell proliferation after 2 months of treatment (2% myeloma cells in the S phase). In conclusion‘this first anti-IL-6 clinical trial demonstrated the feasibility of injecting anti-IL-6 MoAbs, and also a transient tumor cytostasis and a reduction in IL-6-related toxicities. It gave insight into the major biologic activities of IL-6 in vivo and may serve as a basis for further development of anti-IL-6 therapy in myeloma and other IL-6-related diseases.

Summary