Treatment of U-937 GTB cells with tumor-promoting phorbol esters induced adherence of the cells to plastic, with a t1/2 of 20 min. The ED50 was determined to 3.3 nM for phorbol-12,13-dibutyrate and 0.3 nM for 12-O-tetradecanoyl-4 beta-phorbol-13-acetate, whereas the non-tumor-promoting analogue 12-O-tetradecanoyl-4 alpha-phorbol-13-acetate was ineffective at concentrations up to 100 nM. The adh...

Enterovirus 70 (EV70), the causative agent of acute hemorrhagic conjunctivitis, exhibits a restricted tropism for conjunctival and corneal cells in vivo but infects a wide spectrum of mammalian cells in culture. Previously, we demonstrated that human CD55 is a receptor for EV70 on HeLa cells but that EV70 also binds to sialic acid-containing receptors on a variety of other human cell lines. Vir...

Control of neoplastic proliferation reflects in part monocyte/macrophage destruction of target cells--destruction that evidently requires cell-cell interaction. We herein show it to involve the natural plasma opsonin, fibronectin. With two cultured human tumor lines--Malme melanoma and CAK-I renal carcinoma cells--addition of fibronectin, purified to homogeneity, enhances macrophage-mediated cy...

We have previously reported that the human monocytoid cell line U-937-1 constitutively expresses transforming growth factor-alpha (TGF-alpha) and that the steady-state levels of TGF-alpha mRNA as well as TGF-alpha protein release increase when U-937-1 cells are differentiated towards monocytes/macrophages. Interleukin-6 (IL-6), which has been shown to have growth-stimulatory effects on a number...

Abstrad Acquired resistance to diverse chemotherapeutic agents has been associated with overexpression of the P-glycoprotein. We have seleded human U-937 cells for clones resistant to the cytotoxic agents doxorubicin (U-A20) and vincristine (U-V20). The results demonstrate that P-glycoprotein-positive U-A20 and U-V20 cells exhibit resistance to inducers of internucleosomal DNA fragmentation. Al...

Haemophilus ducreyi is a gram-negative obligate human pathogen that causes the genital ulcer disease chancroid. Chancroid lesions are deep necrotic ulcers with an immune cell infiltrate that includes macrophages. Despite the presence of these phagocytic cells, chancroid ulcers can persist for months and live H. ducreyi can be isolated from these lesions. To analyze the interaction of H. ducreyi...