M. Gerloni

Idiotypic vaccination: immunoprotection mediated by anti-idiotypic antibodies with antibiotic activity.

Anti‐Id antibodies were raised in mice against a monoclonal antibody (MoAb KT4) that neutralized the in vitro activity of a Pichia anomala yeast killer toxin. Monoclonal antibody was administered to BALB/C syngeneic mice with different schedules of immunization before intravenous challenge with increasing amounts of yeast killer toxin‐sensitive Candida alhicans cells. The course of candidosis was studied in comparison with mice non‐immunized and immunized with an isotypc‐matched unrelated MoAb subdivided into control groups. Protection was reflected by statistically significant increases in survival rate of mice immunized with MoAb KT4 which showed variable serum levels of yeast killer toxin‐like anti‐Id antibodies. MoAb KT4 affinity chromatography purified mouse anti‐Id antibodies were capable of killing in vitro the yeast ceils of the Candida albicans strain used for the experimental infection.

Mycobactericidal Activity of Human Natural, Monoclonal, and Recombinant Yeast Killer Toxin-like Antibodies

Human natural (KTAb), murine monoclonal (KTMAb), and single-chain recombinant (KTScFv) candidacidal antibodies representing the internal image of a killer toxin from the yeast Pichia anomala (KT), characterized by a wide spectrum of antibiotic activity, exerted a lethal effect against a KT-sensitive multidrug-resistant isolate of Mycobacterium tuberculosis. KTMAb and KTScFv were produced by the hybridoma and DNA technologies, respectively, from the spleen lymphocytes of animals immunized with the idiotype of a KT-neutralizing MAb (MAb KT4), while KTAb were purified against MAb KT4 from the vaginal fluid of women infected with Candida albicans cells bearing an idiotype-like KT cell wall receptor. Mycobactericidal activity was related to the binding of KTAb, KTMAb, and KTScFv to the cell surface of KT-sensitive bacterial cells and was prevented by specific absorption of KT-like antibodies onto MAb KT4. These data identify a novel potentially useful immunotherapeutic approach to tuberculosis.

Interfaces of the yeast killer phenomenon

A new prophylactic and therapeutic antimicrobial strategy based on a specific physiological target that is effectively used by killer yeasts in their natural ecological competition is theorized. The natural system exploited is the yeast killer phenomenon previously adopted as an epidemiological marker for intraspecific differentiation of opportunistic yeasts, hyphomycetes, and bacteria. Pathogenic microorganisms (Candida albicans) may be susceptible to the activity of yeast killer toxins due to the presence of specific cell wall receptors. On the basis of the idiotypic network, we report that antiidiotypic antibodies, produced against a monoclonal antibody bearing the receptor-like idiotype, are in vivo protecting animals immunized through idiotypic vaccination and in vitro mimicking the antimicrobial activity of yeast killer toxins, thus acting as antibiotics.

Killer factor interference in mixed opportunistic yeast cultures

The interaction of the killer yeast Pichia anomala UP 25F with the killer toxin-sensitive clinical isolate Candida albicans UCSC 10S and its natural toxin-resistant mutant derivative C. albicans UCSC 10R were studied under various conditions. A differential inhibition was shown to occur in vitro at pH and temperature values, which are not encountered in vivo, only by using preformed killer toxin, since antagonism due to yeast growth proved to be predominant on the killer effect. Under adverse growth conditions, the P. anomala killer yeast proved to be able to produce an anatoxin antigenically related to the active or heat inactivated killer toxin. These findings suggest that killer toxins may not function as potential virulence factors in the competition between the opportunistic killer yeast P. anomala and sensitive microorganisms for colonization in the course of natural human infections.

Diagnostic potential of IgA coated Candida cells in mucous membrane candidiasis

The significance of in vivo IgA coated yeast cells for the diagnosis of candidiasis of the oral and vaginal mucosal membranes was evaluated by direct immunofluorescence in 70 patients with or without clinical symptoms, shown to be positive for yeast growth in the cultural test. Most of the patients with clinically suspected candidiasis of the mucosal membranes gave positive results by serologic assays in contrast to the majority of symptomless patients. The diagnostic approach proved to be essentially consistent with the clinical signs, persistance of infection, response to antifungal therapy and quantitative cultural data.

Production of yeast killer toxin in experimentally infected animals

The ability of a killer yeast (Pichia anomala, UCSC 25F) to produce toxin in vivo was demonstrated, for the first time, in tissues of normal and immunosuppressed experimentally infected mice by means of a fluorescent antibody technique and a killer toxin specific monoclonal antibody. The possible significance of the findings is discussed.

Candida albicans stress mannoprotein, SMP200, enhances tumour necrosis factor secretion in the murine macrophage cell line ANA-I

Tumour necrosis factor (TNF) secretory activity has been studied in the murine macrophage cell line ANA-1 following in vitro exposure to Candida albicans 200 kDa stress mannoprotein (SMP200). Treatment of ANA-1 murine macrophages with 200 kDa stress mannoprotein results in increased TNF secretion. The phenomenon is (i) dose- and time-dependent, (ii) abrogated by 200 kDa stress mannoprotein preincubation with a specific monoclonal antibody, and (iii) dependent on intact murine macrophage Ca2+/calmodulin-dependent protein kinase function.

DIFFERENTIAL TOXINOGENESIS IN THE GENUS PICHIA DETECTED BY AN ANTI-YEAST KILLER TOXIN MONOCLONAL ANTIBODY

The differential toxinogenesis of 25 isolates belonging to species of the potential yeast killer genusPichia that were previously classified in the genusHansenula was comparatively demonstrated by two serologic techniques (indirect immunofluorescence and double immunodiffusion) by using a monoclonal antibody against a yeast killer toxin produced by a selected strain ofPichia anomala (UCSC 25F). The killer phenotypes of thePichia isolates were evaluated by their ability to kill each other. The results, although of insufficient taxonomic value for a reliable separation of either species or genera, attest to the genomic heterogeneity for the killer character in the genusPichia as well as the presumptive dual killer/sensitive identity for each single isolate.

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabourauds dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabourauds dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.

Botryomyces caespitosus as an agent of cutaneous phaeohyphomycosis

The second known case of a skin infection caused by Botryomyces caespitosus is reported. This case has made it possible to describe the characteristics of this fungus in vivo and to establish it as another agent of phaeohyphomycosis.