Yeast β-Glucan Amplifies Phagocyte Killing of iC3b-Opsonized Tumor Cells via Complement Receptor 3-Syk-Phosphatidylinositol 3-Kinase Pathway

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.

Yeast whole glucan particle (WGP) beta-glucan in conjunction with antitumour monoclonal antibodies to treat cancer

Beta-glucans, biological response modifiers (BRMs) derived from the cell walls of yeast and other sources, have been demonstrated to prime leukocyte complement receptor 3 (CR3), thus enabling these cells to kill tumours opsonised with complement fragment iC3b. Many tumours activate complement via the classical pathway mediated by antitumour monoclonal antibodies (mAbs) or natural antibodies. Studies into the cellular and molecular mechanisms of action have demonstrated that orally administrated yeast beta-glucans are ingested and processed by macrophages. These macrophages secrete the active moiety that primes neutrophil CR3 to kill iC3b-opsonised tumour cells. Extensive studies in preclinical animal tumour models have demonstrated the efficacy of combined oral particulate yeast beta-glucan with antitumour mAb therapy in terms of tumour regression and long-term survival. It is proposed that the addition of beta-glucan will further improve the clinical therapeutic efficacy of antitumour mAbs in cancer patients.

Self-regulation of neutrophils during phagocytosis is modified after severe tissue injury

Neutrophil (PMNL) function is influenced by factors released by other immune cells during the course of the immune response. We investigated the effect of neutrophil cell density and the effect of supernatant of the phagocytosis assay on the phagocytosis activity of PMNLs. The measurements were carried out with naive (control) PMNLs of healthy donors and with PMNLs obtained from patients with severe tissue injury. Phagocytosis index (FI) of PMNLs was determined at cell densities of 7.5 x 10(5)/ml and 15 x 10(5)/ml. E. coli phagocytosis of heparinized whole blood from healthy donors and patients with severe tissue injury was measured and evaluated at three different cell densities (normal, half, and double densities) by flow cytometry. Supernatants of phagocytosis assays of either control or trauma (ISS >18) patient PMNLs were added to the assay suspensions of control and trauma PMNLs. An increase in cell density of healthy donor PMNLs increased yeast phagocytic activity. In cases of tissue injury, PMNLs showed increased phagocytic activity at lower cell densities. E. coli phagocytosis was increased with the increase of cell density, and tissue injury PMNLs were more active at each cell concentration compared to naive cells. Polytrauma supernatants in most cases inhibited, while healthy supernatants mostly increased the yeast phagocytosis of healthy and trauma PMNLs. These results reinforce the idea that primed PMNLs in the presence of microbial agents produce factor(s) which inhibit some of the cell's antimicrobial functions contributing to immune-dysfunction, while unprimed PMNLs produce factor(s) which facilitate antimicrobial countermeasure. These results also demonstrate that reduced phagocytosis of tissue injury primed PMNLs is not due to cytoskeletal changes but to the humoral environment.

Diptericin expression in bacteria infected Drosophila mbn-2 cells - effect of infection dose and phagocytosis

Drosophila haemocytes play a key role in defence against microbial aggression. Their capacity to sense and dispose of bacteria and also to signal to other immune tissues is probably vital to overcome an infection. In this work we used the haemocyte-like mbn-2 cell line to investigate how expression of the antimicrobial peptide diptericin is affected after a high dose bacterial challenge with diaminopimelic acid (DAP)-peptidoglycan Gram-positive and Gram-negative bacteria. We report that diptericin expression is negatively affected by high infection dose and rapid bacterial growth regardless of the type of infection and bacterial virulence and occurs in the absence of mbn-2 cell death. Furthermore we show that the mbn-2 cell population is heterogeneous, containing both phagocytic and nonphagocytic cells and that contact with large numbers of bacteria decreases diptericin expression in the phagocytic cell population.

Negative cross-reactivity of rabbit anti-Malassezia furfur antibodies with other yeasts

Anti-Malassezia furfur monospecific polyclonal antibodies was produced by repeated immunization of rabbit with Malassezia furfur yeast cells mixed with Freud adjuvant. The antibody titres of respective rabbit's serum samples prior to and after each immunization against M. furfur were assayed by indirect immunofluorescence technique using the M. furfur whole yeast antigen fixed in Teflon coated slides. The highest anti-M. furfur antibody titre achieved was 1 in 1280 dilution. At 1:20 dilution, none of the respective serum samples taken at various stages of immunization gave positive immunofluorescent staining against any of the other species of yeasts tested in this study. Anti-M. furfur monospecific polyclonal antibodies produced in rabbit in this study has the potential for diagnostic application in immunohistochemical detection of M. furfur in human tissues.

Identification and possible disease mechanisms of an under-recognized fungus, Aureobasidium pullulans

BACKGROUND

Investigations into the occurrence and health effects of yeast-like fungi in the outdoor air in the US have been limited. We sought to identify a respirable-sized fungus common in the Pasadena air, locate a major source for the emissions and investigate its relevance to allergic disease.

METHODS

Yeast-like fungi sampled from the environment were isolated, microscopically examined and sequenced. Pasadena allergy patients were skin tested with commercially available fungal extracts. Patient serum was immunoanalyzed for specific IgE reactivity. Nearby vegetation was analyzed in a controlled emission chamber to find a major source for the aerosols.

RESULTS

Hyaline unicellular conidia comprised up to 90% (41,250 m(-3) of air) of total fungal counts and generally peaked at night and during periods of rainfall and ensuing winds throughout the fall and winter. Flowers were determined to be a major source of the emissions. The cellular and colonial morphology of isolates were consistent with Aureobasidium species. The sequence of the D1/D2 region of the 26S ribosomal subunit of isolates from flowers showed identity to two strains of Aureobasidium pullulans (black yeast). Seventeen percent (16/94) of atopic individuals had positive skin testing with A. pullulans extract. Patient sera IgE identified several high molecular weight allergens in Aureobasidium extracts.

CONCLUSIONS

Respirable-sized conidia of A. pullulans are emitted from flowers and form high concentrations in the air. They are associated with immediate reactivity on skin tests, bind to patient sera IgE, and might be relevant in allergic upper and lower airway diseases.

Production of a monoclonal antibody against a yeast secreted antigen of Penicillium marneffei

Monoclonal antibody against P. mameffei yeast secreted antigen was produced in order to develop a serological test for penicilliosis marneffei. The yeast form of P. marneffei was cultured in brain heart infusion broth at 37 degrees C for 7 days. A secreted antigen was prepared, partially purified from culture supernatant and subsequently immunized in a BALB/c mouse. Mouse monoclonal antibody was produced from immune spleen cells by a standard hybridoma technique. Specificity of the obtained monoclonal antibody was assessed with yeast secreted antigens for P. mameffei, C. alblicans, C. neoformans, and H. capsulatum by an indirect ELISA. Three of 46 hybrid clones (1 F1, 2G5, and 3G4) reacted positively with P mameffei secreted antigen. 1 F1 and 3G4 were cloned by two rounds of limiting dilution. Partially purified monoclonal antibody and rabbit polyclonal antibody against P. marneffei yeast secreted antigen were used to develop a double antibody sandwich ELISA to detect P. marneffei antigen in plasma or serum samples of 7 patients with penicilliosis marneffei and 5 healthy controls. The sandwich ELISA developed using monoclonal antibody as a capture antibody and rabbit polyclonal antibody as a detector was able to detect P. marneffei antigen in all the plasma and serum samples of penicilliosis marneffei patients, while negative in all the healthy controls. Thus, the monoclonal antibody produced in the present study appeared to be highly specific for P. marneffei and the double antibody sandwich ELISA developed using monoclonal and polyclonal antibodies against the yeast secreted antigen of P. marneffei showed a strong potential for the diagnosis of penicilliosis marneffei.

Yeasts encoding tumour antigens in cancer immunotherapy

Immunotherapy for cancer represents an attractive therapeutic target because of its specificity and lack of toxicity, but products investigated so far have been limited by neutralisation, complexity of manufacturing and requirement for patient-specific products. Recombinant yeast cells are capable of stimulating the immune system to produce highly specific and potent cellular responses against target protein antigens with little toxicity. Data from animal models suggest that Tarmogens (yeast-based immunotherapeutics) can elicit protective immunity against xenografted and chemically induced tumours. This concept is now being tested in a Phase I trial in patients with colorectal, pancreatic and non-small cell lung cancers.

Regulated recruitment of DC-SIGN to cell-cell contact regions during zymosan-induced human dendritic cell aggregation

Zymosan is a beta-glucan, mannan-rich yeast particle widely used to activate the inflammatory response of immune cells. We studied the zymosan-binding potential of human dendritic cells (hDCs) by using specific carbohydrate inhibitors and blocking monoclonal antibodies. We show that DC-specific intercellular adhesion molecule-grabbing nonintegrin (DC-SIGN) is a major nonopsonic recognition receptor for zymosan on hDCs. Indeed, blocking of DC-SIGN inhibited the inflammatory response of DCs to zymosan. We compared the zymosan-binding capacity of hDC-SIGN to that of Dectin-1 and complement receptor 3 (CR3), which are receptors involved in the nonopsonic recognition of these yeast-derived particles. Dectin-1- and DC-SIGN-K562 cells bound to zymosan particles, whereas CR3-K562 cells did not. DC-SIGN and Dectin-1 were also expressed in COS cells to compare their ability to trigger particle internalization in a nonphagocytic cell line. DC-SIGN transfectants were unable to internalize bound particles, indicating that DC-SIGN is primarily involved in recognition but not in particle internalization. Zymosan induced a rapid DC aggregation that was accompanied by a dramatic change of DC-SIGN distribution in the plasma membrane. Under resting conditions, DC-SIGN was diffusely distributed through the cell surface, displaying clusters at the free leading edge. Upon zymosan treatment, DC-SIGN was markedly redistributed to cell-cell contacts, supporting an adhesion role in DC-DC interactions. The mechanism(s) supporting DC-SIGN-mediated intercellular adhesion were further investigated by using DC-SIGN-K562 aggregation. DC-SIGN was highly concentrated at points of cell-cell contact, suggesting a role for enhanced avidity during DC-SIGN-mediated intercellular adhesion.

Immediate hypersensitivity to Malassezia furfur and Candida albicans mannans in vivo and in vitro

BACKGROUND

Elevated and correlative Malassezia furfur (M. furfur) and Candida albicans (C. albicans) mannan-specific IgE have been demonstrated in atopic eczema dermatitis syndrome (AEDS) of the head, neck and shoulder (HNS) region of the skin. The significance of these antibodies in vivo has not been demonstrated.

METHODS

Sixty-five AEDS patients with HNS distribution were included. Serum total IgE (S-IgE) and yeast antigen-specific (Cetavlon-purified mannan and whole extract antigens of M. furfur and C. albicans) IgE were measured and skin prick tests (SPT) were performed with the yeast antigens.

RESULTS

Mannan-specific IgE and SPT were positive in 51 and 48% of patients with M. furfur and in 42 and 22% with C. albicans, respectively. Whole extract-specific IgE and SPT were positive in 85 and 95% of patients with M. furfur and in 91 and 57% with C. albicans, respectively. The highest correlation between specific IgE and SPT was seen with M. furfur mannan (r = 0.60; P < 0.0001). Both M. furfur mannan-specific IgE (r = 0.76; P < 0.0001) and SPT (r = 0.44; P = 0.0005) correlated with S-IgE.

CONCLUSIONS

Mannan-induced immediate hypersensitivity in vivo was demonstrated in SPT. The significant correlation between M. furfur mannan-specific IgE and SPT suggests that mannan is an important allergen in yeast hypersensitive AEDS in vivo.

Phagocytic amoebocyte sub populations in the perivisceral coelom of the sea urchinLytechinus variegatus (Lamarck, 1816)

The echinoderms are deuterostomic animals with a nonspecific immune system similar to that of vertebrates. Among coelomocytes, phagocytic amoebocytes have a key role in the nonspecific immune response in sea urchin, being responsible for microorganisms elimination through phagocytosis and also for humoral secretions of a wide spectrum. Sub-populations of phagocytic amoebocytes (PA) have been previously described and two distinct sub populations in the oral (OR) and aboral (AB) regions of the perivisceral coelom of L.variegatus in the present study were found. In the OR there is a higher number of PA with higher phagocytic capacity after 30 minutes of incubation with yeast and higher percentage of intranuclear iron crystalloids. The germicide capacity under the fluorescence technique did not show any difference. SDS-PAGE analysis showed different protein patterns between coelomocytes of OR and AB. Gravitational force had no effect in PA distribution and no physical barrier was found in the perivisceral coelom. The other coelomocyte (vibratile cells, red spherulocytes and white spherulocytes) populations were not different in OR compared with AB in their distribution. Some aspects of the possible causes of the differences found for PA are discussed in the paper.

Distinct immunologic properties of Penicillium marneffei yeasts obtained from different in vitro growth conditions

A dimorphic fungus Penicillium marneffei is a causative agent of penicilliosis, a life-threatening disseminated disease in immunocompromised hosts predominantly found in southeast Asia and southern China. P. marneffei is the only known Penicillium that possesses a dimorphic characteristic. Since it is difficult to produce large amount of P. marneffei yeasts in vivo for experimentation purpose, yeast cells were produced in different in vitro conditions as alternatives. We interested in investigating the immunologic properties of yeast cells from different culture preparations. It was found that yeast cells obtained from brain heart infusion broth and Sabouraud dextrose broth did not resemble those resided in clinical specimens. A solution of 1% peptone, on the other hand, could induce a direct conidial transition into fission yeasts. Ability of yeast cells in each preparation to activate macrophages was determined by analyzing surface expression of CD40 and CD86 co-stimulatory molecules after two days of co-cultivation. Every P. marneffei yeast cell preparation demonstrated such ability. However, the ones from Sabouraud dextrose broth seemed to induce less phagocytosis. Additionally, although distinct antigenic profiles and lack of conformity in antigenic expression were observed among yeast cells from different culture conditions, most major immunogenic bands were present when Western analysis was performed using polyclonal antisera from penicilliosis patients. The results of the study raise attention on immunological and biochemical characteristics of P. marneffei yeasts if such preparations are to be used in future laboratory investigations.

Extensive MHC class I-restricted CD8 T lymphocyte responses against various yeast genera in humans

The human cellular immune response against 14 distantly related yeast species was analyzed by intracellular cytokine staining of lymphocytes after ex vivo stimulation of whole blood. While the CD4 T cell response was marginal, extensive MHC class I-restricted CD8 T cell responses were detected against a number of species including spoiling, environmental and human pathogenic yeasts. The yeast-specific CD8 T cells expressed interferon-gamma but lacked expression of CD27 and CCR7, indicating that they were end-differentiated effector memory cells. Mainly intact yeast cells rather than spheroplasts were able to induce cytokine expression in T cells demonstrating that the dominant immunogens were located in the yeast cell wall. Together these data underline the importance of the cellular immune response in protecting humans against yeast and fungal infections. And, from another perspective, recombinant yeast suggests itself as a potential vaccine candidate to efficiently induce antigen-specific CD8 T cell responses.

High efficiency recovery and epitope-specific sorting of an scFv yeast display library

In order to more productively utilize the rich source of antigen-specific reagents present in the previously described non-immune single chain fragment variable (scFv) yeast display library, one must be able to efficiently isolate and characterize clones within the library. To this end, we have developed and validated a magnetic bead sorting technique utilizing the Miltenyi Macs system to recover greater than 90% of the antigen-specific clones present in the library. In combination with flow cytometry, we rapidly reduced diversity and enriched for antigen-specific clones in three rounds of selection. Furthermore, we demonstrate the use of pre-existing monoclonal antibodies (mAbs) for antigen labeling and subsequent flow cytometric sorting and characterization of epitope-specific scFv. Combining these two improvements in library screening allowed isolation and characterization of three epitope-specific scFv, including a previously uncharacterized epitope to a 6-kDa protein, epidermal growth factor.

Enumeration of yeasts in dairy products: a comparison of immunological and genetic techniques

Enzyme-linked immunosorbent assay (ELISA) and PCR techniques have been developed for the detection of spoilage yeast species in dairy products. Polyclonal antibodies against live yeast cells (AY) were raised in rabbits by inoculation of a mixture of 10 yeast species frequently associated with dairy products spoilage. AY antibodies were used for the development of two ELISA formats (indirect and double-antibody sandwich ELISA) for the detection of yeast species in milk and yogurt. A PCR assay was also developed for yeast detection in dairy products, using primers designed to amplify a conserved 250-base pair fragment of the 18S rRNA of the yeast species. The results obtained in this work show that ELISA techniques using polyclonal antibodies against viable yeast cells are of limited value for the detection and enumeration of spoilage yeast species in dairy products. On the contrary, PCR amplification of a conserved region of the 18S rRNA of the yeast species allows the homogeneous detection of all the yeast species tested and, combined with an overnight enrichment of samples, could be used for the detection of low levels of viable spoilage yeast species in dairy products.

Is cell surface calreticulin involved in phagocytosis by insect hemocytes?

The innate immune system of insects consists of humoral and cellular components involved in the recognition of and responses to intruding foreign micro- or macroorganisms. Several molecules have been identified so far that recognize molecular patterns present on microorganisms, such as lipopolysaccharides, peptidoglycans and lipoteichonic acid. These molecules, acting as opsonins, trigger immune responses such as phagocytosis, nodule formation, melanization and encapsulation. Here, we investigated the role of calreticulin (CRT) present on the surface of Pieris rapae hemocytes in phagocytosis. Comparative phagocytosis assays using yeast cells showed that hemocytes from different insects exhibit significant variation in their phagocytosing potential and relative CRT involvement.

Direct in vivo screening of intrabody libraries constructed on a highly stable single-chain framework

Single-chain Fv antibody fragments (scFv) represent a convenient antibody format for intracellular expression in eukaryotic or prokaryotic cells. These so-called intrabodies have great potential in functional genomics as a tool to study the function of newly identified proteins in vivo, for example by binding-induced modulation of their activity or by blocking interactions with other proteins. However, the intracellular expression and activity of many single-chain Fvs are limited by their instability and folding efficiency in the reducing intracellular environment, where the highly conserved intrachain disulfide bonds do not form. In the present work, we used an in vivo selection system to isolate novel antigen-binding intrabodies. We screened two intrabody libraries carrying a randomized third hypervariable loop onto the heavy chain of a stable framework, which had been further optimized by random mutagenesis for better behavior in the selection system, and we biophysically characterized the selected variants to interpret the outcome of the selection. Our results show that single-framework intrabody libraries can be directly screened in vivo to rapidly select antigen-specific intrabodies.

The acute phase response of rainbow trout (Oncorhynchus mykiss) plasma proteins to viral, bacterial and fungal inflammatory agents

The innate arm of the immune system responds to inflammatory stimuli by the activation of phagocytes, and by altered levels of several plasma proteins. These changes in plasma proteins comprise a major component of the acute phase response, which is thought to be an adaptive response that contributes to regaining homeostasis after tissue injury or infection. In this study, rainbow trout (Oncorhynchus mykiss) were injected with a variety of potential inflammatory agents, and changes in the concentrations of plasma proteins were sought in polyacrylamide gels in which plasma proteins had been electrophoresed. Bacteria, viruses and yeast all induced changes in plasma protein profiles. Increases were first evident 2 days after injections, and most were evident within 1 week. The greatest number of changes occurred after injection with a Vibrio bacterin emulsified in Freund's incomplete adjuvant. While some proteins increased and others decreased following several treatments, other proteins changed only in response to injections of viruses or viral proteins, and others changed in response to bacterial components. Some proteins that increased after yeast injection decreased after injection of viral components. The partial amino acid sequence of one increased protein identified it as haptoglobin.

Highly specific antibodies determine histone acetylation site usage in yeast heterochromatin and euchromatin

We have developed a highly specific antibody set for acetylation sites in yeast histones H4 (K5, K8, K12, and K16); H3 (K9, K14, K18, K23, and K27); H2A (K7); and H2B (K11 and K16). Since ELISA does not assure antibody specificity in chromatin immunoprecipitation, we have employed additional screens against the respective histone mutations. We now show that telomeric and silent mating locus heterochromatin is hypoacetylated at all histone sites. At the INO1 promoter, RPD3 is required for strongly deacetylating all sites except H4 K16, ESA1 for acetylating H2A, H2B, and H4 sites except H4 K16, and GCN5 for acetylating H2B and H3 sites except H3 K14. These data uncover the in vivo usage of acetylation sites in heterochromatin and euchromatin.

Systemic ketoconazole is an effective treatment of atopic dermatitis with IgE-mediated hypersensitivity to yeasts

BACKGROUND

IgE-mediated hypersensitivity to yeasts is often seen in atopic dermatitis (AD) patients, especially when dermatitis is located in the head, neck, and shoulder regions. Two studies have shown the efficacy of ketoconazole in the treatment of this type of AD, in contrast to results of topical treatment. The objective was to assess the clinical efficacy of antifungal treatment in AD in a randomized, double-blind, placebo-controlled study with oral ketoconazole and yeast-specific IgE levels and saprophytic yeast growth monitored simultaneously.

METHODS

Eighty patients with AD and positive P. ovale and/or C. albicans RAST/skin prick test results were randomized to receive ketoconazole or placebo for 30 days. The yeast growth of skin and pharynx; P. ovale, C. albicans, andS. cerevisiae RAST; serum total IgE; and the severity of the eczema (SCORAD) were assessed at day 0 and thereafter at 1 and 3 months.

RESULTS

A significant improvement was seen in the SCORAD scale in the ketoconazole group at the second visit in comparison to the first visit (P<0.0005; n=36), but not in the placebo group (n=39). Of the individual determinants of the SCORAD, itching (P<0.005), the extent of dermatitis (area percentage), excoriation, lichenification (P<0.01), erythema, papulation, and dryness (P<0.05) improved significantly in the ketoconazole group. In the placebo group, only the extent of dermatitis (area percentage) decreased significantly (P<0.05). In the ketoconazole group, the number of positive P. ovale cultures decreased from 60% to 31% (n=35) compared to the placebo group (64% to 56%; n=39). The clinical response was most significant in female patients with positive yeast cultures.

CONCLUSION

Saprophytic yeasts may be a source of allergens in AD. Thus, patients with AD, yeast growth, and elevated IgE levels to yeasts should be offered antifungal treatment.

UVB IRRADIATION SUPPRESSES CYTOKINE PRODUCTION AND INNATE CELLULAR IMMUNE FUNCTIONS IN MICE

We examined whether ultraviolet-B (UVB) irradiation (6 kJ/m2) alters cytokine production and other innate immune reactions by murine peritoneal macrophages and peripheral neutrophils. Along with these experiments, serum IgG levels were also assessed. In addition, using scanning electron microscopy (SEM) we observed macrophages that had been exposed to UVB in vitro. Results showed that UVB irradiation: (1) decreased IL-12 production while increasing IL-1alpha secretion from macrophages, but had no effect on IL-1alpha from neutrophils; (2) suppressed phagocytosis of macrophages but not of neutrophils; (3) diminished active oxygen production of macrophages but not of neutrophils; (4) had no effect on serum IgG levels; and (5) caused significant cell destruction of macrophages in vitro. These results suggested: (1) that UVB irradiation could induce characteristic suppression of innate immunity; (2) that innate cellular immunity was more susceptible to the effects of UVB irradiation than humoral immunity.

Association between airway hyperreactivity and bronchial macrophage dysfunction in individuals with mild asthma

Little is known about the functional capabilities of bronchial macrophages (BMs) and their relationship to airway disease such as asthma. We hypothesize that BMs from asthmatics may be modulated in their function compared with similar cells from healthy individuals. BMs obtained by induced sputum from mild asthmatics (n = 20) and healthy individuals (n = 20) were analyzed using flow cytometry for CD16, CD64, CD11b, CD14, and human leukocyte antigen-DR expression, phagocytosis of IgG opsonized yeast, and oxidant production. Asthma status was assessed by lung function [percent predicted forced vital capacity and forced expiratory volume in 1 s (FEV(1))], percent sputum eosinophils, and nonspecific airway responsiveness [provocative concentration that produces a 20% fall in FEV(1) (PC(20,FEV1))]. Asthmatics with >5% airway eosinophils (AEo+) had decreased BM CD64 expression and phagocytosis compared with asthmatics with <5% eosinophils (AEo-). Among asthmatics, a significant correlation was found between CD64 expression and BM phagocytosis (R = 0.7, P < 0.009). Phagocytosis was also correlated with PC(20,FEV1) (R = 0.6, P < 0.007), lung function (%predicted FEV(1), R = 0.7, P < 0.002) and percent eosinophils (R = -0.6, P < 0.01). In conclusion, BM from asthmatics are functionally modulated, possibly by Th2 cytokines involved in asthma pathology.

In vitro activity of monoclonal and recombinant yeast killer toxin-like antibodies against antibiotic-resistant gram-positive cocci

BACKGROUND

Monoclonal (mAbKT) and recombinant single-chain (scFvKT) anti-idiotypic antibodies were produced to represent the internal image of a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity, including gram-positive cocci. Pathogenic eukaryotic and prokaryotic microorganisms, such as Candida albicans, Pneumocystis carinii, and a multidrug-resistant strain of Mycobacterium tuberculosis, presenting specific, although yet undefined, KT-cell wall receptors (KTR), have proven to be killed in vitro by mAbKT and scFvKT. mAbKT and scFvKT exert a therapeutic effect in vivo in experimental models of candidiasis and pneumocystosis by mimicking the functional activity of protective antibodies naturally produced in humans against KTR of infecting microorganisms. The swelling tide of concern over increasing bacterial resistance to antibiotic drugs gives the impetus to develop new therapeutic compounds against microbial threat. Thus, the in vitro bactericidal activity of mAbKT and scFvKT against gram-positive, drug-resistant cocci of major epidemiological interest was investigated.

MATERIALS AND METHODS

mAbKT and scFvKT generated by hybridoma and DNA recombinant technology from the spleen lymphocytes of mice immunized with a KT-neutralizing monoclonal antibody (mAb KT4) were used in a conventional colony forming unit (CFU) assay to determine, from a qualitative point of view, their bactericidal activity against Staphylococcus aureus, S. haemolyticus, Enterococcus faecalis, E. faecium, and Streptococcus pneumoniae strains. These bacterial strains are characterized by different patterns of resistance to antibiotics, including methicillin, vancomycin, and penicillin.

RESULTS

According to the experimental conditions adopted, no bacterial isolate proved to be resistant to the activity of mAbKT and scFvKT.

CONCLUSIONS

scFvKT exerted a microbicidal activity against multidrug resistant bacteria, which may represent the basis for the drug modeling of new antibiotics with broad antibacterial spectra to tackle the emergence of microbial resistance.

Membrane attack complex formation on yeast as trigger of selective release of terminal complement proteins from human polymorphonuclear leukocytes

It has recently been shown that measurable amounts of complement proteins, C6 and in particular C7, are released from human polymorphonuclear leukocytes (PMNs). The aim of the present study was to investigate the impact of opsonized Candida albicans on this release. Stimulation with opsonized C. albicans led to a rapid and sustained increase of C6 and C7 in the cell culture supernatant beginning within 5 min of placing in co-culture, whereas co-culture with unopsonized C. albicans or C. albicans mock-opsonized with inactivated human serum did not affect the release. In contrast, even after stimulation employing opsonized C. albicans, no release of the complement component C8 and only trace amounts of C9 were detected. The presence of the membrane attack complex (MAC) on C. albicans after opsonization was demonstrated by indirect immunofluorescence. Opsonization of C. albicans with human serum deficient in or depleted of a terminal complement component resulted in only minor stimulation of C6 and C7 release, although C3 deposition on the surface of C. albicans was not affected as determined by direct immunofluorescence. Detailed analyses with inactivated or deficient sera showed that detection of C6 and C7 was not due to insufficient washing of the opsonized yeast prior to co-culture and suggest that only a small proportion of these proteins was derived from the membrane bound and then cleaved off MAC. Thus, these findings imply that MAC on the fungal surface may represent an additional trigger for the release of C6 and C7 from PMNs, suggesting a new role for the terminal complement complex (TCC) on target membranes as modulator of PMN functions locally at the site of inflammation.