Immunostimulatory effect of Bacillus firmus on mouse lymphocytes

Bacillus firmus (a Gram-positive nonpathogenic and harmless bacterium), was shown to be a strong polyclonal activator of mouse B lymphocytes as estimated by ELISA testing of Ig concentrations in culture supernatants after incubation of BALB/c mouse splenocytes with inactivated bacillus. Synthesis of all main Ig classes and all IgG subclasses was stimulated in vitro, the considerable effect on IgA formation being the most interesting feature. B cell stimulation was T cell dependent, as was demonstrated by the effect of B. firmus on all Ig isotypes and by comparison of lymphocyte response of nu/nu mice and heterozygous nu/+ mice. The effect of B. firmus on splenocyte proliferation was stimulatory or suppressive depending on the dose of the bacterium. Increased synthesis of IFN-gamma and IL-10 (detected by ELISA in splenocyte culture supernatants) showed probable stimulation of Th1 and Th2 subpopulations. Considering the stimulatory effect on IgA formation and macrophage stimulation, B. firmus seems to be a prospective mucosal adjuvant and/or probiotic.

Enhanced systemic and mucosal antibody responses to a model protein antigen after intranasal and intratracheal immunisation using Bacillus firmus as an adjuvant

Bacillus firmus, a non-pathogenic Gram positive (G+) bacterium of the external environment was investigated for immunomodulatory properties. It stimulated an increase in anti-ovalbumin IgG in sera, bronchoalveolar lavages and intestinal washings after both intranasal (i.n.) and intratracheal (i.t.) immunisation, and enhanced anti-ovalbumin IgA in intestinal secretions and in bronchoalveolar lavage fluid after i.n. or i.t. immunisation, respectively. The immunomodulatory effect of B. firmus on antibody formation was antigen specific.

Immune response after adjuvant mucosal immunization of mice with inactivated influenza virus

Satisfactory mucosal immunity in the respiratory tract is very important for protection against influenza. It can be achieved only by mucosal immunization. Mucosal vaccination with inactivated influenza virus may not be sufficiently effective and suitable adjuvants are therefore sought. We tested intratracheal immunization of mice with inactivate B type influenza virus in a mixture with formolized G+ bacterium Bacillus firmus, whose adjuvant effects have previously been documented in another system. The treatment resulted in a marked increase of both systemic and mucosal antibody response in IgG and IgA classes. Stimulation of T lymphocytes after adjuvant immunization was very mild, no proliferation taking place after specific stimulation with antigen in vitro. However, slightly increased systemic (spleen) and local (lungs) production of cytokines without perceptible Th1/Th2 polarization was determined. B. firmus is an efficient adjuvant in respiratory tract immunization while with subcutaneous immunization it lowers the antibody response.

Role of T cells in the adjuvant effect of Bacillus firmus on the immune system of mice: intranasal and intratracheal immunization study with ovalbumin

Functions of T cells were determined after intranasal and intratracheal immunization of mice with ovalbumin (Ova) and Bacillus firmus (Bf), a Gram-positive nonpathogenic bacterium of the external environment, or delipidated Bf (dBf) as adjuvants, with the aim to elucidate the mechanism of support of Ova-specific antibody production caused by Bf that had been observed in an identical experiment. Neither Bf nor dBf in a mixture with Ova stimulated Ova-specific T-cell response tested as antigen-specific blast transformation. By contrast, a mild polyclonal stimulation was observed in splenocytes from mice given dBf. In vitro incubation of splenocytes with 100 micrograms (but not 10 micrograms) of Bf or dBf led to a highly significant inhibition of proliferation below the control level in all groups of animals. Supernatants of splenocyte cultures were further tested for cytokine production. IL-10 and IFN-gamma were released after in vitro challenge with dBf and in some cases also with Bf. Analysis of sera demonstrated that administration of Ova + adjuvant brought about an increase in anti-Ova IgG1, IgG2a and IgG2b whereas treatment with Ova alone caused a rise in IgG1 only. The role of Bf or dBf in the enhancement of antigen-specific antibody production could be in influencing macrophages and inducing cytokine milieu composed of IL-10, IFN-gamma and other factors that leads to a bystander stimulation of specifically activated Ova-B cell receptor (Ova-BCR)-bearing cells.

IgE against food and respiratory allergens in healthy and allergic mothers and their children

IgE against mixtures of common food or respiratory allergens were determined by ELISA in healthy (n = 38) and allergic (n = 62) mothers and their children. Significantly higher level of IgE against respiratory allergens was found in sera of allergic mothers and in cord blood of their children. No correlation between antibody level in maternal and newborn's sera was found; this argues against the transfer of IgE from mother to fetus and points rather to offspring's intrauterine sensitization. Specific IgE level in cord blood was higher in children who developed later allergy than in children who did not. Specific IgE level in colostrum was low both in healthy and allergic mothers; there was no correlation between high concentration of IgE against respiratory allergens in sera of allergic mothers and their colostrum, which does not support the idea of IgE transport from blood to mammary gland. Only slightly increased colostral IgE was detected in allergic mothers whose children manifested allergy later. Allergy of the mother and high level of anti-allergen IgE in her serum and in cord blood are the main predictive factors of future occurrence of allergy in the offspring. A combination of several predictive factors could have higher prognostic value.

Intratracheal and intranasal immunization with ovalbumin conjugated withBacillus firmus as a carrier in mice

Inactivated Bacillus firmus (BF), G+ nonpathogenic bacterium of the external environment, was coupled to ovalbumin (OVA) and used in immunization experiments as antigen carrier. Balb/c mice were immunized thrice intra-tracheally and intra-nasally with conjugates of OVA and BF. Surprisingly, administration of OVA-BF conjugates inhibited anti-OVA IgG response in both sera and mucosal secretions if compared to an exposure to OVA alone. The suppression of antigen-specific antibody production was accompanied by promotion of TH1 phenotype.

Gene expression of subunits of the IL-12 family cytokines in moDCs derived in vitro from the cord blood of children of healthy and allergic mothers

The incidence of allergic diseases is steadily increasing an urgent need to clarify the immunologic processes which occur early in life and signal an increased risk of possible future allergy development. The ratio and maturation state of DCs together with the cytokine environment are important in directing and modulating immune responses. The maturation state (presence of CD83) of cord blood monocyte-derived dendritic cells (moDCs) of 52 children of healthy mothers and 58 children of allergic mothers was estimated by flow cytometry. The capacity of moDCs to express genes for subunits of IL-12 family cytokines was monitored using real-time PCR and protein secretion in cell culture supernatants by ELISA. The percentage of CD83+ moDCs was significantly higher in the allergic group after LPS stimulation (43.11 ± 4.41) in comparison to the healthy group (24.85 ± 3.37). Significantly higher gene expression of subunits of IL-12 family members was observed in moDCs of children of allergic mothers, in comparison with children of healthy mothers. The differences were evident mainly after LPS stimulation of moDCs (healthy group: p19: 3.05 ± 1.24; p28: 14.8 ± 6.8; p35: 1.8 ± 0.6; p40: 8.0 ± 3.5; EBI3: 3.0 ± 1.2; allergic group: p19: 6.1 ± 2.7; p28: 61.4 ± 22.2; p35: 14.9 ± 6.5; p40: 36.4 ± 18.8; EBI3: 11.3 ± 3.2), with the exception of p28, whose expression was significantly higher in the allergic group even without stimulation (healthy group: 0.28 ± 0.12, allergic group: 0.87 ± 0.62). No significant difference between the healthy and allergic groups was found at the protein level. The observation of both increased presence of cell surface activation marker on moDCs and higher IL-12 family gene expression in LPS-stimulated moDCs of children of allergic mothers indicates a higher reactivity of these cells.

Maternal Allergy Status Has No Impact on Neonatal Immune Responses to Allergen Stimuli

Due to the increasing incidence of allergic diseases, there is a strong need to identify a prognostic marker pointing to increased risk of allergy development allowing introduction of early preventive measures. Cord blood seems to be a good source for searching for such marker. The capacity of cord blood cells to respond to common allergens could point to increased predisposition to later allergy development. In our study, cytokines typical of Th1 (IFN-γ), Th2 (IL-5, IL-13) and Treg (IL-10) immune responses were followed at both the level of gene expression and cytokine secretion in cord blood cells of newborns of healthy mothers (children with relatively low risk of allergy development) and allergic mothers (children with relatively high risk of allergy development) stimulated by allergens (pollen from birch and timothy grass, house dust mite, ovalbumin). We have not observed any difference in the response of cord blood cells of neonates of healthy and allergic mothers to allergen in vitro. Both gene expression and secretion of cytokines in response to allergen stimulation were comparable with the unstimulated controls. It seems that early postnatal events will be more decisive for future allergy development than prenatal sensitization of the foetal immune system with allergen in utero in allergic mothers.