PubMed · 10703954
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K M Skubitz, M Kuroki, P Jantscheff, A P Skubitz, F Grunert. CD66e.. https://pubmed.ncbi.nlm.nih.gov/10703954/
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The effects of the production of two closely related cytokines, oncostatin M (OSM) and leukaemia inhibitory factor (LIF), by astrocytoma cells were investigated using the stable cell line human U373-MG, which expressed and secreted both biologically active polypeptides. The expression of LIF by these cells caused resistance to this cytokine due to loss of the LIF receptor (LIFR), from the cell surface, suggesting its retention. In contrast, cells expressing OSM were stimulated by this cytokine, utilizing an autocrine mechanism, and possessed receptors for OSM, but not LIF, on the cell surface. In these cells the continuous up-regulation of OSM-induced gene expression was found even though the Janus kinase-signal transducer and activator of transcription ('JAK/STAT') pathway was almost exhausted due to long-term autocrine stimulation of the cells by OSM. The amount of LIFR was down-regulated in both LIF- and OSM-producing cells and this effect was not found in wild-type U373-MG cells treated with externally added cytokines. To investigate the mechanism of autocrine stimulation by OSM we constructed a stable cell line expressing a form of OSM that is retained in the endoplasmic reticulum (ER). This biologically active cytokine was not secreted, but was localized in the ER. In addition, it did not stimulate the astrocytoma cells in an autocrine manner. We conclude that expression of LIF causes resistance of astrocytoma cells to this cytokine, whereas expression of OSM leads to autocrine stimulation.
Patient-tumor-specific oligonucleotides were generated for the detection of minimal residual disease (MRD) in a highly specific and sensitive clonotypic polymerase chain reaction (cPCR). The clone-specific region of highest diversity, CDR-III, was PCR amplified and sequenced. Nested CDR-III clonotypic primers were used in a semi-nested cPCR with a sensitivity of at least 1 in 10(5) cells. Patients with protocol-eligible Rai intermediate or high-risk chronic lymphocytic leukemia (CLL) received induction with fludarabine 25 mg/m(2) per day for 5 days every 4 weeks for 6 cycles, followed by consolidative high-dose cyclophosphamide (1.5, 2.25, or 3g/m(2)). cPCR was performed on peripheral blood and bone marrow mononuclear cells. All 5 patients achieving a clinical partial remission (PR) studied by cPCR were positive. Five patients achieved nodular PR (nPR) (residual nodules or suspicious lymphocytic infiltrates in a bone marrow biopsy as the sole suggestion of residual disease). Five of 5 patients with nPR were cPCR positive. In contrast, flow cytometry for CD5-CD19 dual staining and kappa--lambda clonal excess detected MRD in only 3 of the same 5 nPR patients, all of whom were cPCR positive, and immunohistochemistry detected MRD in only 1 of 4 assessable patients. Three of 7 CR patients evaluable by cPCR had MRD. Only 1 CR patient had MRD by flow cytometry; that patient was also cPCR positive. These data support the conclusions that nodular PR in CLL represents MRD and that clonotypic PCR detects MRD in CLL more frequently than flow cytometry or immunohistochemistry. (Blood. 2001;97:1929-1936)
Leukostasis and tissue infiltration by leukemic cells are poorly understood life-threatening complications of acute leukemia. This study has tested the hypothesis that adhesion receptors and cytokines secreted by blast cells play central roles in these reactions. Immunophenotypic studies showed that acute myeloid leukemia (AML) cells (n = 78) of the M0 to M5 subtypes of the French-American-British Cooperative Group expressed various amounts of adhesion receptors, including CD11a, b, c/CD18, CD49d, e, f/CD29, CD54, sCD15, and L-selectin. The presence of functional adhesion receptors was evaluated using a nonstatic adhesion assay. The number of blast cells attached to unactivated endothelium increased by 7 to 31 times after a 6-hour exposure of endothelium to tumor necrosis factor (TNF)-alpha. Inhibition studies showed that multiple adhesion receptors--including L-selectin, E-selectin, VCAM-1, and CD11/CD18--were involved in blast cell adhesion to TNF-alpha-activated endothelium. Leukemic cells were then cocultured at 37 degrees C on unactivated endothelial cell monolayers for time periods up to 24 hours. A time-dependent increase in the number of blasts attached to the endothelium and a concomitant induction of ICAM-1, VCAM-1, and E-selectin were observed. Additional experiments revealed that endothelial cell activation by leukemic myeloblasts was caused by cytokine secretion by blast cells, in particular TNF-alpha and IL-1 beta, and direct contacts between adhesion receptors expressed by blast cells and endothelial cells. Thus, leukemic cells have the ability to generate conditions that promote their own adhesion to vascular endothelium, a property that may have important implications for the pathophysiology of leukostasis and tissue infiltration by leukemic blast cells. (Blood. 2001;97:2121-2129)