beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions. This study investigated in vivo and in vitro effects of beta-glucan on lymphoproliferation and interferon-gamma (IFN-gamma) production by splenic cells from C57BL/6 female mice. All experiments were performed with particulate beta-glucan derived from S. cerevisiae. Data demonstrated that both, i.p administration of particulate beta-glucan (20 or 100 µg/animal) and in vitro stimulation of splenic cells (20 or 100 µg/ml of culture) decreased lymphoproliferation and IFN-gamma production induced by concanavalin A. These results suggest that beta-glucan can trigger a down-modulatory effect regulating a deleterious immune system hyperactivity in the presence of a strong stimulus.

Propolis, a beehive product widely used in folk medicine as an antiinflammatory agent, has been attracting researchers' attention to scientifically elucidate its biological properties and therapeutic activities. The aim of this paper was to study the possible effect of propolis on natural killer activity, since propolis immunomodulatory action has been suggested, especially on non-specific immunity. Propolis was produced by africanized honeybees (Apis mellifera L.), collected throughout a whole year, and pooled by season. Hydroalcoholic solutions of propolis were prepared with each pool and administered to rats by gavage over three days. Natural killer activity of non-adherent spleen cells was evaluated by the 51Cr-release cytotoxicity assay against Yac-1 target cells. Our results indicated that the natural killer activity was increased in spleen cells from propolis-treated animals. There were no significant differences related to the seasonal effect on the immunomodulatory action of propolis.

A sandwich-type ELISA technique for specific and sensitive detection of Crotalus durissus terrificus venom antigens, horse-antivenom, human IgG and IgM antibodies was set up. Sixteen patients, 13 males and 3 females aged between 13 to 63 years (mean 33 ± 15) bitten by Crotalus durissus terrificus snakes were studied. Of the 15 patients, 6 had previously received anti-Crotalus venom and no seric venom was detected. For the other 9 patients studied, the venom levels ranged from 2 to 108 ng/ml according to the severity of each case. Seric antivenom was detected up to 44 days after the bite. IgM human antibody levels against Crotalus venom were higher between 3 and 18 days after specific treatment. IgG human antibody levels against Crotalus venom were detected between 30 and 90 days after envenoming. Venom and antivenom levels in cerebrospinal fluid were not observed 24 h after the bite. This suggests that neither the venom nor the antivenom is capable of crossing the blood-brain barrier. In addition, when either the venom or the antivenom is presented to the immune system cells an immune response is prepared.

O efeito imunomodulatório da Cimetidine (CIM), um antagonista do receptor de histamina-tipo 2, foi avaliado na resposta blastogênica a Con A em células de ratos Wistar Furth (WF) infectados pela cepa Y de Trypanosoma cruzi (T. cruzi). Foi observado que apenas na concentração de 10-3M de Cimetidine houve amplificação da resposta blastogênica de esplenócitos normais a Con A. Entretanto, a capacidade mitogênica de esplenócitos de animais infectados foi restaurada na presença de molaridades da droga que variaram entre 10-8 a 10-3. Os resultados demonstraram que a CIM tem o potencial de modular a resposta mitogênica de células de animais infectados pelo T. cruzi, sugerindo um papel imunoregulatório da histamina e/ou células que expressam receptores H2 nesta infecção.

The immunomodulatory effect of cimetidine (CIM), a histamine type-2 receptor antagonist, was evaluated in respect to the blastogenic response to Con A of Wistar Furth (WF) rats infected by the Y strain of Trypanosoma cruzi (T. cruzi). Enhancement of blastogenesis of normal splenocytes was observed at a concentration of 10-3M. However, the splenocytes from infected animals responded to concentrations of CIM ranging from 10-8 to 10-3M. The mitogenic response to Con A of cells from infected animals was restored in the presence of CIM. The results show that CIM modulates the "in vitro" proliferative response of cells from T. cruzi-infected rats and suggest an immunoregulatory role of histamine and/or of cells that express H2 receptors in this infection.