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PubMed1977

Characterization of antigens from type A and B yeast cells of Histoplasma capsulatum.

The antigenic composition of cytoplasmic extract and culture filtrate antigens of type A and B yeast cells of Histoplasma capsulatum grown in a synthetic medium was studied. These preparations from type A and B yeast cells contained varying amounts of protein, carbohydrates, and protein-carbohydrate complexes. The antigenic analysis of these preparations was performed by antigen-antiserum absorption with subsequent immunodiffusion and cross-immunoelectrophoresis with absorption in situ in an intermediate gel. All protein antigens observed in culture filtrate of either type A or B yeast cells were also present in the cytoplasmic extracts of the same type. The cytoplasmic extract of type A and B yeast cells each contained certain characteristic antigens that were not shared by the other type. Rocket immunoelectrophoresis with different molecular weight fractions of the antigenic preparations from both types indicated the polydisperse nature of Histoplasma yeast cell antigens.

Antigen-Antibody Reactions↗
PubMed1979

Cross-reactivity between antigens of Coccidioides immitis, Histoplasma capsulatum and Blastomyces dermatitidis in lymphocyte transformation assays.

The cross-reactivity of four Coccidioides antigens, three Histoplasma antigens, and two Blastomyces antigens were determined in lymphocyte transformation assays of 11 coccidioidin-reactive, histoplasmin-nonreactive subjects (group I), 13 coccidioidin-nonreactive, histoplasmin-reactive persons (group II), and 13 subjects who were skin test negative to both antigens (group III). Mycelial and yeast (or spherule)-phase antigens of the three fungi were included. Significant cross-reactivity was obtained with both coccidioidins, spherulin, and the alkali-soluble, water-soluble cell wall antigen of C. immitis, to the extent that the responses of histoplasmin-reactive persons were not statistically different (P > 0.05) from those of coccidioidin-reactive persons. In contrast, optimal dilutions of Histoplasma mycelial and yeast-phase lysates effectively distinguished (P < 0.01) responses of histoplasmin- and coccidioidin-reactive persons. The alkali-soluble cell wall antigen of H. capsulatum showed extensive cross-reactivity at most concentrations and was markedly stimulatory to lymphocytes of skin test-negative persons. Blastomycin elicited significant cross-reactions in histoplasmin-sensitive subjects and to a lesser extent in coccidioidin-sensitive subjects. The alkali-soluble cell wall antigen cross-reacted in cultures of histoplasmin-reactive persons but not in those of coccidioidin-reactive persons. All antigens effectively distinguished (P < 0.001) homologous responses of skin test-positive persons (groups I and II) from those of skin test-negative persons (group III). The extensive cross-reactivity in lymphocyte transformation assays in the absence of cross-reactivity in skin tests suggests that these two immune responses may be mediated by different T lymphocyte populations, may be elicited by different antigenic components, or both.

Antigens, Fungal↗
PubMed1984

T-cell hybridoma-produced lymphokine that activates macrophages to suppress intracellular growth of Histoplasma capsulatum.

Supernatants from concanavalin A-stimulated T-cell hybridomas activated macrophages to suppress the intracellular growth of Histoplasma capsulatum and to kill tumor cells. The supernatants had high interferon activity and were pH 2 sensitive and heat resistant. Gamma interferon is suggested to be among the active substances in the supernatants. Neither alpha interferon nor beta interferon activated macrophages for the Histoplasma growth inhibitory activity.

Animals↗
PubMed1988

Role of L3T4+ T cells in host defense against Histoplasma capsulatum.

Cell-mediated immunity is critical in host resistance against the pathogenic fungus Histoplasma capsulatum. To explore the role of L3T4+ T cells in protection of mice against H. capsulatum infection, we examined the effect of in vivo treatment with anti-L3T4 monoclonal antibody (MAb) GK1.5 on the course of murine disseminated histoplasmosis. Treatment with anti-L3T4 antibody caused a profound and selective depletion of L3T4+ T cells that was associated with a significant increase in the number of H. capsulatum CFU recovered from the spleens of mice infected for 1 week. In addition, none of the infected mice treated with MAb GK1.5 survived a sublethal challenge with H. capsulatum yeasts. Histopathological examination of spleens from mice infected for 1 week revealed the presence of granulomatous inflammation in mice depleted of L3T4+ T cells and in infected controls. However, silver stains demonstrated that spleens of infected mice given MAb GK1.5 contained a greater number of yeasts than did spleens from infected controls. MAb GK1.5 did not cause reactivation of infection when administered for 2 weeks beginning 4 weeks after inoculation of Histoplasma yeasts. MAb GK1.5 did not alter the functional properties of murine macrophages as measured by antigen presentation, production of interleukin-1 in response to lipopolysaccharide, and phagocytosis of H. capsulatum yeasts. These results suggest that the L3T4+ T-cell subset is an essential constituent of the cell-mediated immune defense against H. capsulatum infection.

Animals↗
PubMed1988

Characterization of antigenic determinants in histoplasmin that stimulate Histoplasma capsulatum-reactive T cells in vitro.

Although antigen-reactive T lymphocytes play a central role in the host response to Histoplasma capsulatum, little is known of the nature of Histoplasma antigens recognized by these cells in vitro. Employing a murine T-cell line and two clones that are reactive with histoplasmin, we examined whether activation of T cells by histoplasmin required the presence of carbohydrate or protein moieties. The approach taken was to modify carbohydrate or protein molecules in histoplasmin by chemical or enzymatic digestion or by lectin adsorption. In parallel, antigen was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis to correlate alterations in functional activity with changes in the electrophoretic appearance of histoplasmin. Treatment of histoplasmin with periodate (0.1 M, 0.05 M, and 0.01 M) or with the endoglycosidases N-glycanase and endoglycosidase H sharply diminished the capacity of histoplasmin to trigger responses by T cells. Reactivity of T cells to histoplasmin that had been adsorbed with lectins binding mannose, glucose, or galactose was reduced by greater than 70%; conversely, the responses by T cells to antigen that had been adsorbed with lectins specific for fucose, N-acetylgalactosamine, or N-acetylglucosamine ranged from 82 to 91% of that to control antigen. Proliferative responses by T cells to histoplasmin that had been digested with chymotrypsin, protease, or trypsin were 2 to 43% of control values. The electrophoretic appearance of histoplasmin was modified by some but not all of the treatments. Partially purified H and M antigens triggered proliferation of T cells. Thus, both carbohydrates and proteins must be present to induce optimal responses by T cells. A portion of the carbohydrates is N linked to proteins, and alpha-D-mannose (or alpha-D-glucose) and beta-D-galactose are the sugar ligands of carbohydrate-containing antigens.

Adsorption↗
PubMed1997

Calcium dependence and binding in cultures of Histoplasma capsulatum.

Histoplasma capsulatum is a pathogenic fungus with two distinct morphologies and lifestyles. The saprophytic form of this organism, a mold, thrives in soil and is especially abundant in the Ohio and Mississippi River valleys. Its parasitic counterpart, a yeast, colonizes phagolysosomes of mammalian macrophages. We have observed a major difference in the calcium requirements of the two forms of Histoplasma, potentially implicating the phagolysosome as a calcium-limiting compartment. Deprivation of calcium by the addition of EGTA to culture media inhibited the growth of mycelial H. capsulatum but had no effect on yeast growth in vitro. In addition, yeasts released a calcium-binding protein (CBP) detectable by a 45CaCl2 blotting technique. CBP was a major component of yeast culture supernatant and was also detectable by ruthenium red staining, another assay for calcium-binding activity. Conversely, mycelial H. capsulatum did not produce CBP, a finding that correlates with the dependence of mycelia on calcium for growth. We also describe here the purification of CBP from yeast culture supernatant by reversed-phase high-pressure liquid chromatography.

Calcium↗
PubMed1974

Effect of cyclophosphamide on Histoplasma capsulatum infections in mice.

Mice were injected intraperitoneally (i.p.) with 300 mg of cyclophosphamide (CY)/kg of body weight, and 24 h later were injected i.p. with varying dosages of yeast-phase cells of Histoplasma capsulatum. At specific time intervals organs were removed, ground, and cultured to determine the number of viable organisms contained in the spleen, liver, and lungs. Injection of mice with CY was found to cause a dramatic increase in the numbers of parasites isolated from these organs when compared with non-drug-treated controls. Mice given 10(7) yeast cells showed the largest increase in colony numbers. A greater than fivefold increase in the numbers of organisms isolated from the spleens of CY and 10(3) yeast cell-treated mice, as compared with non-drug-treated animals, was observed at all time periods. The general trend for infected control animals was a decrease in colony numbers. All mice given CY plus 10(7) yeast cells intravenously (i.v.) died by day 20 postinfection. Mice given CY and 10(7) yeast cells i.p. showed no evidence of fatal Histoplasma infection. Deaths occurring by day 5 in CY-treated animals injected with H. capsulatum yeast cells i.v. or i.p. were considered due to bacterial infection or toxicity, or both. Hepatosplenomegaly was observed in mice treated with CY and 10(7) yeast cells of H. capsulatum. Enlarged lungs were also noted. CY control mouse spleens weighed 30% less than normal spleens. Organs of animals injected with H. capsulatum alone did not vary significantly from those of normal mice. Complete drug-induced suppression of humoral antibody response was achieved for 10 days, as determined by hemagglutination titrations.

Animals↗
PubMed1972

Deoxyribonucleic acid base composition of the yeastlike and mycelial phases of Histoplasma capsulatum and Blastomyces dermatitidis.

The base composition in moles percent guanine plus cytosine (%GC) of both nuclear and mitochondrial deoxyribonucleic acid (DNA) isolated from the yeastlike and mycelial phases of the dimorphic fungal pathogens Histoplasma capsulatum and Blastomyces dermatitidis was determined by techniques of thermal denaturation and CsCl buoyant density gradient equilibrium centrifugation. The mean observed values for GC content of nuclear DNA from H. capsulatum and B. dermatitidis were 47.3 and 48.2%, respectively. What is speculated to be mitochondrial DNA was found to be 34.0% for H. capsulatum and 34.3% for B. dermatitidis. Thermal denaturation curves for Blastomyces DNA indicated a bimodality in thermal denaturation profiles, thereby suggesting a significant mitochondrial DNA contamination. Mitochondrial DNA appeared to represent a smaller percentage of the total DNA prepared from Histoplasma, and was not observed consistently to affect%GC values as determined by thermal denaturation profiles. On the basis of the now known perfect stage of B. dermatitidis (Ajellomyces dermatitidis) as a member of the family Gymnoascaceae, the close approximation of%GC content of nuclear DNA of this fungal organism with that of H. capsulatum suggests possible phylogenetic relationship. It is suggested that the just reported, but as yet unclassified, perfect stage of H. capsulatum may be found to be phylogenetically a primitive form of the Gymnoascaceae.

Biological Evolution↗
PubMed1961

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.

Animals↗
PubMed1961

Preparation of a fluorescent antibody specific for the yeast phase of Histoplasma capsulatum.

Kaufman, Leo (Communicable Disease Center, Atlanta, Ga.) and William Kaplan. Preparation of a fluorescent antibody specific for the yeast phase of Histoplasma capsulatum. J. Bacteriol. 82:729-735. 1961.-Rabbit anti-Histoplasma capsulatum globulin was conjugated with fluorescein isothiocyanate. This labeled antibody, in addition to staining six strains of H. capsulatum, exhibited strong cross-staining with ten strains of Blastomyces dermatitidis and numerous other species of fungi. Adsorption of the labeled antiglobulin either twice with cells of B. dermatitidis or twice with cells of Coccidioides immitis and once with cells of B. dermatitidis resulted in a good staining fluorescent antibody reagent, specific for yeast phase cells of H. capsulatum. Attempts to define the specific labeled antibody by the Ouchterlony procedure were unsuccessful. The specific conjugate did not give a complement fixation titer with yeast phase cells of B. dermatitidis or with coccidioidin. It did, however, show a 1:16 complement fixation titer with homologous yeast phase cells and a weaker reaction with histoplasmin.

Animals↗
PubMed1966

Occurrence of serotypes among Histoplasma capsulatum strains.

Kaufman, Leo (Communicable Disease Center, Atlanta, Ga.), and Sharon Blumer. Occurrence of serotypes among Histoplasma capsulatum strains. J. Bacteriol. 91:1434-1439. 1966.-Extensive studies with a fluorescent antibody specific for the yeast form of Histoplasma capsulatum indicated that, although most strains of H. capsulatum stained intensely, others stained weakly and some did not stain. These observations suggested that antigenic variants of the fungus existed. To test this hypothesis, reciprocal cross-staining and adsorption procedures were performed with fluorescein-labeled antiglobulins to four strains of H. capsulatum. Fifty-six strains of H. capsulatum and 11 strains of H. duboisii were studied. The data indicate that at least five serotypes of H. capsulatum occur. One is closely related antigenically to H. duboisii and Blastomyces dermatitidis.

Adsorption↗
PubMed1966

Antigenic properties of the cell wall and other fractions of the yeast form of Histoplasma capsulatum.

Pine, Leo (Communicable Disease Center, Atlanta, Ga.), Clarence J. Boone, and Dave McLaughlin. Antigenic properties of the cell wall and other fractions of the yeast form of Histoplasma capsulatum. J. Bacteriol. 91:2158-2168. 1966.-Yeast-form cells of Histoplasma capsulatum were fractionated in an attempt to obtain complement-fixing antigens with greater specificity than those of the currently used whole yeast form. No specific fraction was isolated. Rupture of the whole cell produced soluble and insoluble highly antigenic fractions. The soluble fractions rapidly lost antigenicity. Marked reduction of activity of some particulate fractions was also observed. The purified cell wall, stripped of its protein components, was antigenic, relatively stable, and demonstrated low cross-reactivity with heterologous sera. All fractions cross-reacted with sera from cases of North American blastomycosis to a greater degree than did the whole yeast-form antigen of H. capsulatum. The production of certain cellular fractions varied with the strains used. In complement-fixation tests, insignificant differences in specificity and antigenicity were found with whole-cell antigens from 13 H. capsulatum strains as well as with purified cell wall fractions prepared from 2 of these strains.

Antigens↗
PubMed1967

Serological response of rhesus monkeys to histoplasma, Blastomyces, and Coccidioides antigens.

Fifteen adult rhesus monkeys were inoculated with nonviable Histoplasma capsulatum, Blastomyces dermatitidis, or Coccidioides immitis. Antibody assays were made periodically during a 2-year period by use of a complement-fixation (CF) test employing four antigens and a latex-agglutination test. Selected sera were also studied in an immunodiffusion test and a coccidioidin-precipitin test. The serological patterns obtained with the anti-Histoplasma, anti-Blastomyces, and anti-Coccidioides monkey sera were comparable to those of sera from patients with diseases caused by the respective organisms. Rhesus monkeys should provide a good laboratory model for additional studies, including the influence of multiple antigenic stimuli on serologic response and patterns. Monkeys could also be used for the production of antisera required for studies to improve the specificity of the currently available CF antigens.

Animals↗
PubMed1968

Cell wall composition and serological reactivity of Histoplasma capsulatum serotypes and related species.

The composition of the cell walls of strains of Histoplasma capsulatum that were reactive in the complement-fixation test and that reacted with fluorescein-tagged specific anti-H. capsulatum serum were compared with the cell walls of H. capsulatum and Histoplasma duboisii that did not react in these serological tests. The cell walls of the serologically reactive strains of H. capsulatum were much more susceptible to the action of proteinases and to chitinase than were the serologically nonreactive strains, but were less susceptible to hydrolysis by 3% NaOH or 2 n H(2)SO(4). The walls of the serologically reactive strains had higher chitin, amino acid, and hexosamine contents, but they were lower in a "lactic acid" component that was released by alkaline hydrolysis of the nonreactive strains. The cell walls of strains of H. duboisii were similar to the walls of the serologically nonreactive strains of H. capsulatum. Chemical analyses of the cell walls of the various strains clearly support the serological typing of H. capsulatum and H. duboisii strains reported by Kaufman and Blumer.

Animals↗
PubMed1980

Evaluation of the exoantigen test for identification of Histoplasma species and Coccidioides immitis cultures.

Recently it was demonstrated that certain fungal pathogens could be rapidly and accurately identified on the basis of their exoantigens. Mycelial-form cultures of the Histoplasma species consistently appear to produce either H or M antigens, or both, whereas cultures of Coccidioides immitis produce tube precipitinogen, heat-labile precipitinogen, or heat-labile F antigens. Three laboratories each evaluated 48 cultures by the exoantigen procedure for the identification of Histoplasma spp. and C. immitis. One hundred forty-four cultures were tested, and 143 (99.3%) were correctly identified as Histoplama spp. or C. immitis, or neither. The simple and rapid exoantigen test appears to be a sensitive and specific method for identification of these fungi.

Antigens, Fungal↗
PubMed1981

Radioimmunoassays that use 125I-labeled protein A for determination of Histoplasma capsulatum-specific immunoglobulin G, A, and M class antibodies in histoplasmosis.

A radioimmunoassay for determination of human immunoglobulin G, A, and M class antibodies to Histoplasma capsulatum is reported. Yeast-phase antigen from H. capsulatum was adsorbed onto polyvinyl chloride microtiter plates as the solid phase. Human antibodies were allowed to react with this antigen, followed by addition of rabbit anti-human alpha- or mu-heavy chain sera. 125I-labeled staphylococcal protein A was then added and allowed to bind the human and rabbit immunoglobulin G. With this technique, it is possible to evaluate individual human serum samples for antigen-specific classes of antibodies. This assay may be useful for monitoring the immune response in histoplasma infections.

Antibodies, Fungal↗
PubMed1997

Comparison of radioimmunoassay and enzyme-linked immunoassay methods for detection of Histoplasma capsulatum var. capsulatum antigen.

The purpose of this study was to compare the conventional radioimmunoassay (RIA) to an enzyme-linked immunoassay (EIA) for the measurement of Histoplasma antigen in banked urine specimens. A correlation between the two methods would allow the EIA to be used as a nonradioactive alternative to the established 125I RIA. The study used stored urine from patients diagnosed with histoplasmosis during an outbreak in Indianapolis which began in 1988. Control specimens from healthy adults, patients with other fungal infections, urinary tract infections, or nonfungal pneumonia were also tested. Both the RIA and EIA were run concurrently. The RIA system measured antigen levels of 0.4 to 27.0 RIA units, while the EIA measured antigen levels of 0.6 to 20.1 units. Both the EIA and RIA detected measurable antigen levels in urine from 50 of 56 patients (89%) with disseminated disease and 11 of 30 patients (37%) with self-limiting disease. One of 96 control specimens, from a patient with paracoccidioidomycosis, was positive with both systems. Antigen levels measured by EIA correlated well with those measured by the established RIA method (correlation coefficient, 0.974). The EIA is an acceptable alternative to the RIA for measuring Histoplasma antigen levels in urine specimens.

Adult↗