lewis-x-antigen and Leukemia--Myelomonocytic--Acute

Resting human NK cells require a two-stage activation process that we have previously described as "priming" and "triggering." NK-sensitive tumor cells provide both priming and triggering signals. NK-resistant tumors evade lysis, mostly by failure to prime; however, we recently reported a tumor cell line (CTV-1) that primes resting NK cells but fails to trigger lysis. In this article, we report two additional leukemia cell lines that prime NK cells but are resistant to lysis. Tumor-mediated NK priming is via CD2 binding to a ligand within CD15 on the tumor cell. NK-resistant RAJI cells became susceptible to NK lysis following transfection and expression of CD15. Blockade of CD15 on K562 cells or on CD15(+) RAJI cells significantly inhibited lysis, as did blockade of CD2 on resting NK cells. NK priming via CD2 induced CD16 shedding, releasing CD3ζ to the CD2, leading to its phosphorylation and the subsequent phosphorylation of linker for activation of T cells and STAT-5 and synthesis of IFN-γ. Blockade of C-type lectin receptors significantly suppressed the tumor-mediated priming of NK cells, whereas blockade of Ig-superfamily-like receptors had no effect at the NK-priming stage. Tumor priming of resting NK cells was irrespective of HLA expression, and blockade of HLA-killer Ig-like receptor interactions did not influence the incidence or degree of priming. However, CD15-CD2 interactions were critical for NK priming and were required, even in the absence of HLA-mediated NK inhibition. Tumor-mediated priming led to a sustained primed state, and the activated NK cells retained the ability to lyse NK-resistant tumors, even after cryopreservation.

Topics: CD2 Antigens; Cell Differentiation; Cell Line, Tumor; Cell Lineage; Coculture Techniques; Cytotoxicity, Immunologic; Disease Resistance; Fucosyltransferases; Humans; Killer Cells, Natural; Leukemia, Monocytic, Acute; Leukemia, Myelomonocytic, Acute; Lewis X Antigen; Ligands; Lymphocyte Activation; Lymphoma, Non-Hodgkin; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Protein Binding; Receptors, KIR; Resting Phase, Cell Cycle; Signal Transduction

It has been shown previously that multilineage human hematopoiesis is maintained within human fetal bone marrow (BM) fragments implanted into severe combined immunodeficient (SCID) mice. We describe here an application of this animal model, the SCID-hu mouse, to the study of human myeloid leukemias. BM cells from 8 patients with various types of myeloid leukemias were injected directly into human bone grafts in the SCID-hu mouse. Cells from 7 patients grew in the human marrow without spreading to the mouse marrow. Cells from 6 of these patients were successfully transferred in vivo to secondary SCID-hu recipients. The surface phenotype and the cytologic features of the leukemia cells were conserved during passage in vivo. Thus, human myeloid leukemia cells could be reproducibly propagated in the human marrow environment in SCID-hu mice. The differentiation of promyelocytic leukemia cells in the SCID-hu mice was induced by all-trans retinoic acid, suggesting that the biologic features of the leukemia cells were maintained as well. Finally, evidence for a leukemic progenitor cell population in one case of acute myelogenous leukemia was provided with this system. This model may provide a useful tool for studying the biology of human myeloid leukemia as well as for evaluating new therapeutic modalities for myeloid leukemias.

Topics: Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Bone Marrow; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid; Leukemia, Myeloid, Acute; Leukemia, Myelomonocytic, Acute; Leukemia, Promyelocytic, Acute; Lewis X Antigen; Mice; Mice, SCID; Neoplasm Transplantation; Sialic Acid Binding Ig-like Lectin 3; Transplantation, Heterologous; Tretinoin

OMA-AML-1 was established from a patient with acute myelomonocytic (M4) leukemia at fifth relapse when blasts were greater than 85% CD34+, CD15-. Leukemic cells were established in suspension culture and independently grown as subcutaneous tumors in SCID mice. Cells growing in suspension culture underwent differentiation by phenotypic and morphologic criteria. In contrast, cells grown as subcutaneous solid tumors in SCID mice maintained progenitor cell characteristics with high-density CD34 expression and lack of morphologic differentiation. A tendency toward differentiation to CD15+, CD34- cells in vitro and self-renewal of CD34+, CD15- cells in vivo was consistently demonstrated regardless of whether cells were initially grown in vitro or in vivo. The cell line maintains both a CD34+, CD15- progentitor cell pool and a non-overlapping, CD15+, CD34- differentiating cell compartment after more than 1 year in continuous culture. Cell cycle analysis and cloning experiments were consistent with terminal differentiation occurring in the CD15+, CD34- population. The cell line shows concentration-dependent proliferative responses to interleukin (IL)-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-6, but not to granulocyte CSF (G-CSF). OMA-AML-1 appears to mimic several features of normal myeloid hematopoiesis and should prove useful for the study of normal and malignant myeloid differentiation.

Topics: Animals; Antigens, CD; Antigens, CD34; Cell Differentiation; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Interleukin-3; Interleukin-6; Leukemia, Myelomonocytic, Acute; Lewis X Antigen; Mice; Mice, Nude; Mice, SCID; Neoplasm Transplantation; Phenotype; Stem Cells; Tumor Cells, Cultured