Capsulatum Yeast Research Articles

Immunoregulation in disseminated murine histoplasmosis: disturbances in the production of interleukins 1 and 2.

Production of IL 1 and IL 2 by splenocytes from C57BL/6 mice was measured at wk 1, 3, 8, and 14 after i.v. inoculation with 6 X 10(5) Histoplasma capsulatum (Hc) yeasts. As compared with age-matched controls, IL 1 production by splenocytes from Hc-infected mice was reduced severely at wk 1 and 3 of infection, greater than normal at wk 8, and within normal range at wk 14. IL 2 production was also reduced at wk 1 and 3 of infection; it was normal at wk 8 and was elevated at wk 14. Indomethacin and catalase failed to restore IL 1 production by splenocytes from infected mice, and exogenous IL 1 did not augment IL 2 production by these cells. A factor capable of suppressing the activity of IL 2 was detected in supernatants of concanavalin A-stimulated splenocytes from infected animals at wk 1 and 3 of infection, respectively. No factor capable of suppressing IL 1 activity was detected. Thus, the deficits of cell-mediated immunity in mice with systemic Hc infection may derive, in part, from impaired amplification of the immune response consequent to abnormal generation of IL 1 and IL 2.

Detection of an antigenic cell wall layer inHistoplasma capsulatum

Histoplasma capsulatum yeast cells have been studied by immunoelectron microscopy using rabbit polyclonal antisera and a biotin-avidin-peroxidase detection system. An antigenic surface layer has been visualized in the cell wall of immunostained organisms. This layer was not seen in samples prepared by standard electron microscopic methods or in negative controls used with the immunocytochemical technique. Without immunostaining the cell wall of Histoplasma appeared almost transparent. In contrast, after immunoperoxidase staining the cell wall was conspicuous, bounded by the darkly stained outer layer. This electron dense layer, appeared to be a reservoir of surface antigens that were recognized by anti-Histoplasma antibodies.

Immunoenzymatic absorption test for serodiagnosis of paracoccidioidomycosis.

A sensitive enzyme-linked immunosorbent assay is described for paracoccidioidomycosis serodiagnosis, with antigen represented by filtrates from Paracoccidioides brasiliensis cultures. Cross-reactivities were, however, observed with sera from patients with other mycoses such as histoplasmosis, lobomycosis, cryptococcosis, candidiasis, and sporotrichosis. These cross-reactions did not occur when we used as antigen Yarzabal E2 component prepared by affinity fractionation of the culture filtrates. Specific results could also be obtained with the whole filtrate antigen when sera were absorbed with Histoplasma capsulatum yeast and mycelial components. Besides a very high sensitivity (100% of the 69 cases of paracoccidioidomycosis tested), this assay showed no false-positive results for the 206 non-paracoccidioidomycosis sera studied, including those from patients with other mycotic diseases.

Human lymphocyte blastogenesis induced by living and deadHistoplasma capsulatumyeasts and soluble yeast autolysate

Human peripheral blood mononuclear cells were cultured with either replicating yeast phase Histoplasma capsulatum, intact dead yeasts of soluble yeast phase autolysate antigen for induction of lymphocyte blastogenesis. H. capsulatum replicated to the same extent in cultures of lymphocytes from histoplasmin skin test-positive and negative cell donors, but stimulated far greater blastogenesis in the former. Dead H. capsulatum yeasts, which were more easily quantified, caused nearly as much specific blastogenesis as live yeasts. Blastogenesis was induced by as few as 1 dead yeast per 10,000 lymphocytes, indicating the antigenic potency of Histoplasma yeasts. Specific blastogenesis was also caused by soluble yeast autolysate. Thus, replicating H. capsulatum yeasts, dead yeasts and autolytically released soluble yeast phase antigen each stimulated specific blastogenesis of lymphocytes from persons sensitized to H. capsulatum in vivo.

Activation of the alternative complement pathway by Histoplasma capsulatum.

The present study was performed to determine whether Histoplasma capsulatum (yeast phase) is able to activate the alternative complement pathway. H. capsulatum yeasts were shown to consume C3 in C4-deficient guinea pig serum. Immunoelectrophoretic conversion of alternative pathway component factor B confirmed that C3 consumption was mediated by activation of the alternative pathway. These results demonstrate that H. capsulatum is able to activate the alternative complement pathway.

Ribosomal RNA from the yeast and mycelial phases of Histoplasma capsulatum

Purified yeast and mycelial phase rRNA from Histoplasma capsulatum was heat-formaldehyde deantured and analyzed by polyacrylamide gel electrophoresis. An average difference of 6.9% was seen in electrophoretic migration between the yeast and mycelial phase denatured 17 S rRNAs that was not apparent for the native 17 S rRNAs. This difference was statistically significant and could not be accounted for by random variation among gels electrophoresed in parallel. A significant difference was not found between the 25 S rRNAs of yeast and mycelial phase cells. Molecular weights of 1.28 × 10 6 for both the yeast and mycelial phase 25 S rRNA, and 0.79 × 10 6 and 0.73 × 10 6 for the yeast and mycelial phase 17 S rRNA, were estimated by using denaturing conditions which minimize conformational contributions to electrophoretic migration in polyacrylamide gels. In addition, we find that both the yeast and mycelial phase 17 S and 25 S rRNAs of H. capsulatum are smaller than their respective counterparts in S. cerevisiae. The results indicate that a structural difference may exist, at least between the 40 S subunits of H. capsulatum yeast and mycelial phase ribosomes.

Acute Histoplasmosis: Description of an Outbreak in Northern Louisiana

An outbreak of acute histoplasmosis occurred in northern Louisiana in September 1977. All six men who cleared a field of bamboo cane known to be a blackbird roosting site were affected. All had clinical and roentgenographic findings of acute pulmonary histoplasmosis, and all recovered. Seroconversion or fourfold rise in antibody to Histoplasma capsulatum yeast--or mycelial-form antigens were demonstrated in five. Immunodiffusion testing showed that all six patients developed H capsulatum M bands, and two developed H bands specific for active infection. The H capsulatum was isolated from the soil in the cane field. This is the first report of an outbreak of histoplasmosis in Louisiana and the first known isolation of H capsulatum from Louisiana soil.

Ribonucleic acid polymerases of the yeast phase of Histoplasma capsulatum.

Ribonucleic acid (RNA) polymerases of Histoplasma capsulatum (yeast phase) were fractionated by phosphocellulose chromatography and partially characterized. Three distinct, active fractions were seen. The major RNA polymerase species was inhibited strongly by alpha-amanitin, whereas the other two were resistant. When either slightly purified (HSE) extract or the major active component was assayed at 37 C, the incorporation of tritiated uridine monophosphate into RNA stopped after 10 to 15 min. In contrast, the synthesis continued for at least 1 h at 23 C. The other two RNA polymerase species exhibited higher rates of incorporation when tested at 37 C, and continued to synthesize RNA even after 60 min. However, by that time the levels of incorporation at 23 C were higher than at 37 C for all three enzymes. The temperature sensitivity was not affected by changing substrate concentration or employing either native or denatured calf thymus deoxyribonucleic acid as a template. These results are compared with the data obtained with RNA polymerases from different fungi and other organisms. A possible involvement of RNA polymerase(s) in morphological differentiation of H. capsulatum is discussed.

Immunologic significance of aspergillin antigens of six species of Aspergillus in the serodiagnosis of aspergillosis.

The diagnostic value of the complement fixation and the immunodiffusion tests using aspergillin prepared from each of 6 species of Aspergillus (A. fumigatus, A. fischeri, A. flavus, A. terreus, A. nidulans, and A. niger) was determined by testing sera from 85 patients with active aspergillosis, 80 patients with other fungal infections, and 20 normal subjects. Aspergillin was sensitive and specific for the serodiagnosis of aspergillosis when used in the immunodiffusion test and sensitive and relatively specific in the complement fixation test. There was a direct linear relationship between the number of precipitin bands and the strength of the complement fixation titers. High complement fixation titers or strong precipitin reactions were good evidence of the common saprophytic form of aspergillosis, regardless of the presence or absence of an aspergilloma. Complement fixing antibodies to Histoplasma capsulatum yeast antigens were found in the sera of 56 per cent of the patients with aspergillosis. Sera fro...

Effect of saramycetin on the fine structure of Histoplasma capsulatum.

WhenHistoplasma capsulatum yeast cells were grown in the presence of partially inhibitory concentrations of saramycetin, electron microscopy revealed that the proportion of apparently damaged cells was a function of the concentration of the antibiotic. Evidence of early damage consisted of irregularity of outline, followed by progressive lysis of internal structures leading to residual dense granules, membranes, and the cell wall. Normal yeast cells of the strain studied were found to possess intranuclear bodies of a type apparently not previously described.

Respiratory infection of mice with Histoplasma capsulatum.

Mice were infected by exposure to varying doses ofHistoplasma capsulatum yeast cells in the Henderson aerosol apparatus.

Effect of vaccines prepared from Histoplasma capsulatum and other yeasts on experimental tuberculosis.

Hedgecock, Loyd W. (Veterans Administration Hospital, Kansas City, Mo.). Effect of vaccines prepared from Histoplasma capsulatum and other yeasts on experimental tuberculosis. J. Bacteriol. 82:115-123. 1961.-Resistance to experimental tuberculosis was enhanced by the injection of a nonviable vaccine prepared from Histoplasma capsulatum in the mycelial phase but not by the organism in the yeast phase. Acquired resistance was established within 7 days or less and usually maintained for at least 29 days. When both mycelium vaccine of H. capsulatum and a vaccine prepared from tubercle bacilli were utilized in vaccination, the results were additive (in terms of acquired resistance) provided that an interval of 3 weeks was maintained between injection of each of the vaccines. Resistance to tuberculosis was also demonstrable 14 days after the injection of nonviable preparations of Brucella abortus and Cryptococcus neoformans, as well as by yeast and mycelial vaccines of Blastomyces dermatitidis and Sporotrichum schenckii. Resistance decreased significantly when the animals were challenged 29 days after vaccination, with the exception of those injected with the yeast phase of B. dermatitidis.

Immunization of mice with polysaccharides of Histoplasma capsulatum.

SummaryH. capsulatum strain G17 (M) polysaccharide was capable of producing active resistance against intravenously induced histoplasmosis in mice. However, mice immunized with a H. capsulatum whole yeast cell antigen showed greater resistance when the H. capsulatum polysaccharide immunized, whole cell immunized and nonimmunized control mice were challenged by the intravenous injection of known numbers of viable H. capsulatum yeast phase organism.

Antigenic fractions specific for Histoplasma capsulatum in the complement fixation reaction.

SummaryA method was described for the isolation of antigens from the supernates of H. capsulatum yeast phase cultures by precipitation with zinc and alcohol accompanied by removal of protein by the water-chloroform method. Antigens prepared by this method fixed complement only with sera from rabbits infected with H. capsulatum. The antigens reacted with serum from both early and late bleedings of Histoplasma-infected rabbits, but failed to react with serum from animals with B. dermatitidis, C. immitls, S. schenckii, and C. albicans.

Experimental Histoplasmosis in a Dog: A Nonfatal Case

Experimental histoplasmosis in five dogs was described in a recent article by Ruhe and Cazier (1). Dog 1 of this group, after showing marked evidence of infection by X-ray and by clinical signs, appeared completely recovered several months after infection. A detailed description of this case is given primarily to point out that nonfatal histoplasmosis may occur in dogs, and to describe the pathology that was observed in a recovered case. The dog involved was a black-and-white male terrier about 1 year old. On March 17, 1948, the dog was inoculated with 1 cc. of a 1:10 dilution of packed Histoplasma capsulatum yeast cells of strain H-629 isolated from a human case in Kansas City, Kansas. The injection was made directly into the right lung, between the 6th and 7th ribs, midway between the shoulder crest and the ventral median line, using a 2-inch 20-gage needle and a 1 cc. glass tuberculin syringe.