Mechanisms of altered in vitro antibody response in the rat by a small synthetic polymer

Application of chemical immunomodulators to the treatment of cancer and AIDS

A number of potential advantages, development of promising new agents, and the discovery of synergy with cytokines or cell products continue to spur research into the application of chemical immunomodulators for the treatment of cancer and AIDS. In preclinical in vitro and in vivo systems, chemical immunomodulators definitely modulate the immune system and have therapeutic efficacy. Although clinical trials have shown the ability of these agents to modulate the human immune system, thus far chemical immunomodulators have generally not fulfilled the therapeutic promise generated in animal models for the treatment of human diseases. While the discrepancy in results between animal models and human trials is obvious, the basis is not apparent. Species differences in elimination kinetics, presentation of active drug at the site of action, and the development of tachyphylaxis have been postulated as reasons for the minimal activity of these agents in humans. In addition, the use of investigational techniques established for cytotoxic agents may not be appropriate for immunomodulators. As with any immunomodulator, determining an optimal immunostimulatory dose and schedule and applying the therapy to patients with minimal tumor burden would perhaps be more appropriate than use of a maximally tolerated dose in patients with advanced disease. A dose-immunological effect relationship has recently been demonstrated for levamisole at doses higher than those used for many years in levamisole trials (99). While research and clinical investigation have identified several potentially useful chemical immunomodulators, the elementary understanding of the biochemical mechanisms involved in immunoregulation remains basic. Future research must elucidate these mechanisms, particularly in humans, to maximize the benefits of chemical immunomodulators as single agents or combined with cytotoxic chemotherapeutic agents, surgery, radiation therapy, other immunomodulators, and antiviral agents.

Enhanced survival in antibiotic-treated murine fecal peritonitis by administration of copovithane, a selective immunostimulative polymer

The purpose of this study was to determine the effect of an immunostimulative polymer, Copovithane (Cpv), plus antibiotics (netilmicin and clindamycin) in a murine model of fecal peritonitis. Cpv augments humoral immunity with little effect on T cells and is nontoxic. Cpv 100 mg/kg iv administered at the onset of sepsis increased median survival time (MST) by 40-55% over untreated controls. Four experiments were performed. Cpv in combination with antibiotics when given at the time of onset of sepsis was significantly more effective than antibiotics alone (MST 235 vs 105 hr, P less than 0.05 at 144, 168, 192, 216 hr). In the second and third experiments Cpv alone and with antibiotics was administered 15 hr after the onset of sepsis. Cpv significantly augmented survival over controls in the second experiment (MST 87 vs 60 hr, P less than 0.025 at 96 hr). Cpv plus antibiotics was significantly better than antibiotics alone in the third experiment (MST 111 vs 64 hr, P less than 0.05 at 72 hr, P less than 0.005 at 120 hr). In the final experiment, Cpv did not inhibit growth of 20 bacterial species in agar and liquid media. Cpv significantly enhances survival in murine fecal peritonitis even when administered after the onset of sepsis; furthermore Cpv plus antibiotics in established peritonitis produces longer survival than antibiotics alone. Synthetic immunomodulators such as Cpv could eventually play a significant role in the management of peritoneal infection in humans.