IMPAIRED AUTOLOGOUS MIXED LYMPHOCYTE REACTION CORRELATED WITH DECREASED EXPRESSION OF HLA-Ⅱ ANTIGENS ON MONOCYTES IN PATIENTS WITH MYELOID LEUKEMIA

The proliferative response of T-cells to autolo-gous non-T-cells is referred to as the autologous mixed lymphocyte reaction (AMLR). Recent studies have suggested that AMLR represents a mechanism of immune regulation in vivo. We investigated AMLR in patients with acute- and chronic myeloid leukemia (AML and CML). AMLR was found to be significantly depressed (P<0.001) in AML patients (n=17, cpm=532±95) and CML patients (n=13, cpm=688±99) when compared with that of their healthy HLA-identical siblings serving as controls (n=17, cpm=4152±619 and n=13 cpm=4086±421, respectively). In order to understand the cellular basis of the defective AMLR in patients with AML end CML, we performed mitogen-treated T-cell cultures analysis of T-cell subsets and HLA-Ⅱ antigen detection on monocytes. The results indicated that the defect of AMLR in patients resided at the stimulator monocyte level rather than at the responder T-cell level. Enumeration of monocytes reactive with monoclonal antibody Tu22, which recognizes determinants of HLA-DQ, demonstrated that ML patients had a significantly decreased (P<0.091) number of circulating Tu22+ monocytes when compared with normal controls. These studies suggest that a deficiency of HLA-DQ+ monocytes contributes to the depression of AMLR in ML and possibly underlies the abnormalities of immune response present in this disease.

Synsepalum dulcificum extracts exhibit cytotoxic activity on human colorectal cancer cells and upregulate c-fos and c-jun early apoptotic gene expression

Objective: To explore cytotoxicity of Synsepalum dulcificum(S. dulcificum) Daniell(Sapotaceae) on human colon cancer(HCT-116 and HT-29), human monocytic leukemia(THP-1) and normal(HDFn) cell lines, and its effect on the expression of early apoptotic genes, c-fos and c-jun. Methods: Leaf, stem and berry of S. dulcificum were separately extracted by using 2 solvents, 10% ethanol(EtOH) and 80% methanol(MeOH). PrestoB lue~? cell viability assay and q RT-PCR assay were conducted to examine the above objectives respectively. Results: Stem MeOH, stem EtOH, and berry EtOH extracts of S. dulcificum were cytotoxic to HCT-116 and HT-29 human colon cancer cells. For HCT-116, IC_(50) values of these 3 extracts were not significantly different(P>0.05) from that of the positive control bleomycin(IC_(50) of 33.57 μg/mL), while for HT-29, IC_(50) values of these 3 extracts were significantly lower(P<0.05) than that of bleomycin(IC_(50) of 25.24 μg/mL). None of the extracts were cytotoxic to the THP-1 monocytic leukemia cells and HDFn normal human dermal fibroblasts. For both HCT-116 and HT-29, these extracts significantly up-regulated(P<0.05) the expression of c-fos and c-jun compared to the untreated negative control. Conclusions: The results of this study suggest that cytotoxicity of stem MeOH, stem EtOH, and berry EtOH extracts of S. dulcificum on HCT-116 and HT-29 colon cancer cells is due to the induced apoptosis which is caused by the up-regulation of the expression of early apoptotic genes, c-fos and c-jun.

DDIT4 mediates the proliferation-promotive effect of IL-34 in human monocytic leukemia cells

Interleukin 34(IL-34)is a cytokine that shares the receptor with colony-stimulating factor 1(CSF-1).IL-34 is involved in a broad range of pathologic processes including cancer.We previously demonstrated that IL-34 promoted the proliferation and colony formation of human acute monocytic leukemia(AMoL)cells.However,the mechanism has not been elucidated.Here,by analyzing the gene profiles of Molm13 and THP1 cells overexpressing IL-34(Molm13-IL-34 and THP1-IL-34),upregulation of the DNA damageinducible transcript 4(DDIT4)was detected in both series.Knockdown of DDIT4 effectively inhibited the proliferation,promoted apoptosis and colony formation in Molm13-IL-34 and THP1-IL-34 cells.Our results suggest that DDIT4 mediates the proliferationpromotive effect of IL-34 whereas does not mediate the promotive effect of IL-34 on colony formation in AMoL cells.

Up-regulation of TIMP-2 expression promotes SHI-1 leukemic cells proliferation and infiltration in immunodeficiency mice

Background MMPs and TIMPs play important roles in tumor angiogenesis and invasion. Studies have shown that TIMP- 2 has two roles in tumor invasion. However, its role in leukemic infiltration has not been well investigated. This study explored the roles of TIMP-2 in extramedullary infiltration of acute monocytic leukemic SHI-1 cells both in vitro and in vitro. Methods A retroviral vector carrying the human TIMP-2 cDNA was constructed and transfected into the monocytic leukemic cell line SHI-I. The expression of TIMP-2 in the positive clones was determined. The proliferation of SHI-1 cells was examined by MTT assay. Trans-Matrigel invasion assays were used to investigate the infiltration ability in vitro. SHI-1 cells were intravenously injected into pre-traated nu/nu mice to investigate the infiltration ability feature in vitro. Results The expression of TIMP-2 on the cell membrane was significantly elevated in SHI-1/TIMP-2 cells. Over- expression of TIMP-2 promoted the cells proliferation and the invasions in vitro. The SHI-1/TIMP-2 cells demonstrated higher infiltration ability when intravenously injected into nu/nu mice. Conclusion Over-expression of TIMP-2, especially on the cell membrane, may play important roles in promoting the proliferation and infiltration of SHI-1 leukemic cells.