laminaran and Lymphoma

Anti-tumor mAbs hold promise for cancer therapy, but are relatively inefficient. Therefore, there is a need for agents that might amplify the effectiveness of these mAbs. One such agent is beta-glucan, a polysaccharide produced by fungi, yeast, and grains, but not mammalian cells. Beta-glucans are bound by C receptor 3 (CR3) and, in concert with target-associated complement fragment iC3b, elicit phagocytosis and killing of yeast. Beta-glucans may also promote killing of iC3b-opsonized tumor cells engendered by administration of anti-tumor mAbs. In this study, we report that tumor-bearing mice treated with a combination of beta-glucan and an anti-tumor mAb show almost complete cessation of tumor growth. This activity evidently derives from a 25-kDa fragment of beta-glucan released by macrophage processing of the parent polysaccharide. This fragment, but not parent beta-glucan, binds to neutrophil CR3, induces CBRM 1/5 neoepitope expression, and elicits CR3-dependent cytotoxicity. These events require phosphorylation of the tyrosine kinase, Syk, and consequent PI3K activation because beta-glucan-mediated CR3-dependent cytotoxicity is greatly decreased by inhibition of these signaling molecules. Thus, beta-glucan enhances tumor killing through a cascade of events, including in vivo macrophage cleavage of the polysaccharide, dual CR3 ligation, and CR3-Syk-PI3K signaling. These results are important inasmuch as beta-glucan, an agent without evident toxicity, may be used to amplify tumor cell killing and may open new opportunities in the immunotherapy of cancer.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Monoclonal; Antineoplastic Combined Chemotherapy Protocols; beta-Glucans; Cell Line, Tumor; Complement C3b; Humans; Injections, Intravenous; Intracellular Signaling Peptides and Proteins; Lymphoma; Macrophage-1 Antigen; Macrophages; Mice; Mice, Inbred C57BL; Opsonin Proteins; Phosphatidylinositol 3-Kinases; Protein-Tyrosine Kinases; Signal Transduction; Survival Analysis; Syk Kinase; Yeasts

Efficacy of fluconazole (FLCZ), an anti-fungal agent of triazole derivatives, was evaluated in patients with systemic mycoses and suspected mycoses associated with hematologic malignancies including leukemia, myelodysplastic syndrome and malignant lymphoma. Plasma beta-D-glycan levels, the differences between the levels determined toxicolor test and in endospecy test, were also investigated. Fourteen patients with systemic mycoses and 31 patients with suspected mycotic infections were treated with intravenous administration of FLCZ at a daily dose of 400 mg. Excellent to good responses were observed in 4 of the 14 patients (28.6%) with definitive diagnosis of mycosis, and in 18 of the 31 patients (58.1%) with suspected fungal infections, with an overall efficacy rate of 48.9% (22/45). Levels of plasma beta-D-glycan correlated well with efficacies of FLCZ in 19 of 30 patients. In several cases, however, plasma beta-D-glucan levels were low during the entire course of treatment. Even in 10 cases of definite mycosis, 4 cases showed low levels of plasma beta-D-glucan (below 15 pg/ml by repeated determinations). The results indicate that FLCZ is an effective agent for the treatment of severe systemic fungal infections in patients with hematologic disorders. Deep seated mycosis cannot be ruled out even when its plasma levels of beta-D-glucan are low.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; beta-Glucans; Biomarkers; Drug Evaluation; Female; Fluconazole; Glucans; Humans; Leukemia; Lymphoma; Male; Middle Aged; Mycoses

It has been reported that beta-1,3-D-glucan isolated from Alcaligenes faecalis (TAK) promoted tumor cytolysis by mouse polymorphonuclear leukocytes (PMN). We investigated the effect of serum on mouse PMN tumor cytolysis induced by TAK and other PMN stimulators. Addition of fetal calf serum (FCS) to the cytolysis assay enhanced tumor cytolysis by PMN in a dose-dependent manner. Sera obtained from horses, mice, and rats were also effective enhancers of PMN tumor cytolysis. When FCS was added after the assay was under way, the enhancing effect decreased proportionally to the time elapsed. The enhancing activity was detected over a broad range of fractions with a peak at 170 kD by fractionation on a Superose 6 column. The responsible factor(s) in serum was stable after treatment at 60 degrees C, 30 min or after lowering the pH to 2. Mouse PMN stimulated with TAK increased production of hydrogen peroxide in the presence of FCS.

Topics: Alcaligenes; Animals; beta-Glucans; Blood; Cattle; Cytotoxicity, Immunologic; Glucans; Horses; Hydrogen Peroxide; Lymphokines; Lymphoma; Mammary Neoplasms, Experimental; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Neoplasms, Experimental; Neutrophils; Rats; Tumor Cells, Cultured