epiglucan and Leukemia-P388

We recently identified dectin-1 (betaGR) as a major beta-glucan receptor on leukocytes and demonstrated that it played a significant role in the non-opsonic recognition of soluble and particulate beta-glucans. Using a novel mAb (2A11) raised against betaGR, we show here that the receptor is not dendritic cell-restricted as first reported, but is broadly expressed, with highest surface expression on populations of myeloid cells (monocyte/macrophage (Mphi) and neutrophil lineages). Dendritic cells and a subpopulation of T cells also expressed the betaGR, but at lower levels. Alveolar Mphi, like inflammatory Mphi, exhibited the highest surface expression of betaGR, indicative of a role for this receptor in immune surveillance. In contrast, resident peritoneal Mphi expressed much lower levels of betaGR on the cell surface. Characterization of the nonopsonic recognition of zymosan by resident peritoneal Mphi suggested the existence of an additional beta-glucan-independent mechanism of zymosan binding that was not observed on elicited or bone marrow-derived Mphi. Although this recognition could be inhibited by mannan, we were able to exclude involvement of the Mphi mannose receptor and complement receptor 3 in this process. These observations imply the existence of an additional mannan-dependent receptor involved in the recognition of zymosan by resident peritoneal Mphi.

Topics: 3T3 Cells; Animals; Ascitic Fluid; beta-Glucans; Bone Marrow Cells; Cell Line; Cell Lineage; Cell Membrane; Glucans; Lectins, C-Type; Leukemia P388; Macrophages, Alveolar; Macrophages, Peritoneal; Membrane Proteins; Mice; Mice, Inbred C57BL; Monocytes; Myeloid Cells; Nerve Tissue Proteins; Neutrophils; Opsonin Proteins; Organ Specificity; Receptors, Immunologic; RNA, Messenger; Spleen; Zymosan

A growth-suppressing factor for bovine artery endothelial cells (BAEGSF) was purified from the conditioned medium of a mouse lymphoma P388D1 cell culture in the presence of 100 microg/ml carboxymethylated curdlan. The purification steps included, in order, ammonium sulfate fractionation and eight stages of column chromatography on Macro-Prep Ceramic Hydroxyapatite, Q-Sepharose, Sephacryl S-300 HR, Matrex PBA-30, CHT II, Resource-Q, anti-bovine serum albumin (BSA) agarose, and Superdex 200HR columns. The purified BAEGSF showed two bands with silver staining on a sodium dodecyl sulfate polyacrylamide gel under reducing conditions (SDS-PAGE) and their molecular weights were estimated as approximately 55 and 63 kDa, while the molecular weight of the purified BAEGSF was estimated as about 65 kDa by gel filtration using Superdex 200HR. This result shows that BAEGSF obtained from Superdex 200HR chromatography is a partially purified preparation and suggests that one of the two bands on SDS-PAGE corresponds to BAEGSF. BAEGSF was shown not to have a lethal effect on endothelial cells, but had an inhibitory action on the proliferation of these cells. Furthermore, the growth-suppressing activity of BAEGSF for bovine artery endothelial cells (BAE) was not inhibited by anti-transforming growth factor-beta (TGF-beta), anti-tumor necrosis factor-alpha (TNF-alpha), and anti-interleukin-1 (IL-1) antibodies. These results suggest that BAEGSF is different from TGF-beta, TNF-alpha, and IL-1 which have been reported to inhibit BAE growth.

Topics: Animals; Antineoplastic Agents; Arteries; beta-Glucans; Cattle; Cell Division; Culture Media, Conditioned; Electrophoresis, Polyacrylamide Gel; Endothelium, Vascular; Glucans; Leukemia P388; Mice; Molecular Weight; Tumor Cells, Cultured

Conjugates of 1-beta-D-arabinofuranosylcytosine (araC) with two polysaccharides such as polygalacturonic acid (PGA) and carboxymethylated yeast beta-D-glucan (CMG) were tested for their antileukemic activity in vitro on a L1210 cell line in suspension culture, in soft agar assay and in vivo on L1210, L1210/araC- and P388-leukemia-bearing mice. Both conjugates showed high activity in vitro in soft agar assay, compared with araC. Single administration of PGA-araC or CMG-araC increased the survival time 1.5 x or 1.7 x, respectively, compared with araC in vivo in L1210-leukemia-bearing mice. The conjugates were not active against araC-resistant leukemia line L1210/araC. The marked effect of both PGA-araC and CMG-araC against leukemia L1210 and P388 is probably due to the prolonged release of free araC from conjugates caused by hydrolysis.

Topics: Animals; beta-Glucans; Cytarabine; DNA; Female; Glucans; Leukemia L1210; Leukemia P388; Male; Mice; Mice, Inbred DBA; Pectins