Zymosan A

Opsonized-zymosan-stimulated polymorphonuclear cells show a cyanide-insensitive oxygen consumption. We have investigated whether opsonized-zymosan could induce similar metabolic change in human blood platelets. Preparation of intact human blood platelets, obtained by separation through a Ficoll layer (23% w/v) were challenged with opsonized-zymosan. The polymorphonuclear cell contamination was less than 1/10(8) platelets. The opsonized-zymosan-stimulated platelets showed an increase of oxygen consumption. The mean of oxygen burst measured by a polarographic method with a Clark electrode was 11 nmole/10(9) platelets/min (S.E.M. 4; n = 15). The duration of the burst was 2 min. Unstimulated platelets did not show the oxygen burst. The inhibitors of respiratory chain and prostaglandin synthesis completely abolished the oxygen consumption by opsonized-zymosan-stimulated platelets. The simultaneous addition of NADH (1 mM) and opsonized-zymosan induced a burst of oxygen consumption, which occurred after a variable lag phase (10-12 min) from the stimulation, also in the presence of inhibitors. This burst, which lasted about 1 min, amounted to 10 nmole/10(9) platelets/min (S.E.M. 2; n = 15) and it was higher in the presence of NAN3, a catalase inhibitor. Zymosan treated with hydrazine or heated plasma (56 degrees C) did not cause increased oxygen consumption. Inulin or inulin-treated serum did not stimulate platelets. In these experimental conditions some NADH disappeared, as shown by isotachophoresis. The results demonstrated that an immunological stimulus may activate a membrane-linked cyanide-insensitive oxygen metabolizing system.

Vaccination is the most effective method for controlling the infectious diseases that threaten the poultry industry worldwide. The use of adjuvants or immunostimulants is often necessary to improve vaccine efficacy, particularly for vaccines based on recombinant protein or inactivated pathogens. The adjuvant effects of zymosan A on antigen-specific antibody production were investigated in chickens. First, the optimal adjuvant dose of zymosan A was determined. Chicks were immunized with dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) at a dosage of 2 mg/kg body weight (BW) with or without zymosan A (at a dosage of 0.5 mg/kg BW) co-administration at 4, 5 and 6 weeks of age. Different routes of immunization (oral, intranasal (i.n.), intraocular (i.o.), subcutaneous (s.c.), intramuscular (i.m.) and intraperitoneal (i.p.) were tested. Anti-DNP IgY and IgA concentrations in serum samples from all chicks were measured by an enzyme-linked immunosorbent assay. The results revealed that co-administration of zymosan A with DNP-KLH significantly increased anti-DNP IgY concentrations in chicks immunized by the oral and s.c. routes of administration when compared with control groups. In addition, co-administration of zymosan A with DNP-KLH significantly increased anti-DNP IgA concentrations in chicks immunized by the oral, i.o. and s.c. routes compared with control groups. In conclusion, zymosan A is a useful immune-potentiator adjuvant in chickens, and its co-administration with vaccine antigens enhances humoral immune responses.

Paracoccidioides brasiliensis is the major etiologic agent of Paracoccidioidomycosis (PCM), the most frequent human deep mycosis in Latin America. It is proposed that masking of β-glucan in P. brasiliensis cell wall is a critical virulence factor that contributes to the development of a chronic disease characterized by a long period of treatment, which is usually toxic. In this context, the search for immunomodulatory agents for therapeutic purposes is highly desirable. One strategy is to use pattern recognition receptors (PRRs) ligands to stimulate the immune response mediated by phagocytes. Here, we sought to evaluate if Zymosan, a β-glucan-containing ligand of the PRRs Dectin-1/TLR-2, would enhance phagocyte function and the immune response of mice challenged with P. brasiliensis. Dendritic cells (DCs) infected with P. brasiliensis and treated with Zymosan showed improved secretion of several proinflammatory cytokines and expression of maturation markers. In addition, when cocultured with splenic lymphocytes, these cells induced the production of a potential protective type 1 and 17 cytokine patterns. In macrophages, Zymosan ensued a significant fungicidal activity associated with nitric oxide production and phagolysosome acidification. Importantly, we observed a protective effect of Zymosan-primed DCs delivered intranasally in experimental pulmonary PCM. Overall, our findings support the potential use of β-glucan-containing compounds such as Zymosan as an alternative or complementary antifungal therapy.Lay summary:We report for the first time that Paracoccidioides brasiliensis-infected phagocytes treated with Zymosan (cell wall extract from bakers' yeast) show enhanced cytokine production, maturation, and fungal killing. Also, Zymosan-primed phagocytes induce a protective immune response in infected mice.