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Cerebrospinal fluid antibodies detected by ELISA against a 33-kDa antigen from spherules of Coccidioides immitis in patients with coccidioidal meningitis. The National Institute of Allergy and Infectious Diseases Mycoses Study Group.

Antibodies against a 33-kDa antigen from Coccidioides immitis were detected by ELISA in patients' cerebrospinal fluid (CSF). Anti-33-kDa antibodies were detected at dilutions > 1:80 in only 1 (1.4%) of 73 patients without coccidioidal meningitis but in 74 (71.8%) of 103 with meningitis. Anti-33-kDa antibodies were detected in 53 (91.4%) of 58 patients whose anti-coccidioidal complement-fixing (CF) antibodies were detectable and in 21 (46.7%) of 45 patients whose CSF was negative by CF test (positive predictive value, 99%; negative predictive value, 71%; sensitivity, 72%; specificity, 99%). Anti-33-kDa antibodies, among which IgG1 was the dominant subclass, increased when infections worsened and decreased when patients' conditions improved. Antibody concentration appeared to be independent of most baseline findings, although only 1 of 5 patients coinfected with human immunodeficiency virus had initially detectable antibodies. Measurement of anti-33-kDa antibodies is a sensitive indicator of coccidioidal meningitis and of its clinical course.

Antibodies, Fungal

Relationship of progesterone- and estradiol-binding proteins in Coccidioides immitis to coccidioidal dissemination in pregnancy.

Pregnancy is a major risk factor for coccidioidal dissemination. Because rates of Coccidioides immitis growth and endospore release are stimulated in vitro by levels of unbound progesterone and 17 beta-estradiol that are achievable, in vivo, in the sera of pregnant women (i.e., 10(-9) to 10(-8) M), a specific-hormone-binding system in C. immitis was sought. Fungal cytosols were incubated with tritiated steroids plus or minus radioinert steroids to identify specific binding systems. All five strains of C. immitis tested exhibited specific saturable binding for progestin, estrogen, androgen, and (to a lesser extent) corticosterone and glucocorticoid hormone classes. Only low or inconsistent estrogen or androgen binding was found in Blastomyces dermatitidis and Torulopsis glabrata. Cryptococcus neoformans, Paracoccidioides brasiliensis, and non-albicans Candida species showed no binding. Scatchard analysis of progestin and estrogen binding in C. immitis revealed a high-capacity, low-affinity binding system that was unaffected by RNase and DNase, but 40 to 60% degraded by trypsin or heating. Ammonium sulfate precipitation resolved a high-affinity, low-capacity binding system (Kd = 1.24 X 10(-9) to 3.60 X 10(-8) M; number of binding sites = 0.014 to 0.20 pmol/mg of protein). The Kd of this system is sufficient to compete for unbound hormone in the sera of pregnant women. The high-capacity, low-affinity system may serve as a repository for hormone before its attachment to the specific binder. These studies suggest that the effects of nanomolar concentrations of sex hormones on C. immitis may be mediated by a specific cytosol protein-binding system and that stimulatory events observed in vitro may have relevance for the mechanism of coccidioidal dissemination in pregnancy.

Alpha-Globulins

Reactivity of alkali-soluble, water-soluble cell wall antigen of Coccidioides immitis with anti-Coccidioides immunoglobulin M precipitin antibody.

The alkali-soluble, water-soluble cell wall antigen of Coccidioides immitis (C-ASWS) mycelia and spherules was shown to react with anti-Coccidioides immunoglobulin M (IgM) precipitin antibody, both in the classical tube precipitin test and in the immunodiffusion assay for tube precipitin antibody (IDTP). The reactions obtained between C-ASWS and reference IgM precipitin antibody were identical to the reaction obtained when reference coccidioidin (CDN) was used. Definitive proof that C-ASWS extracts contain antigenic determinants that are reactive with IgM tube precipitin antibody was obtained by solid-phase immunoadsorption. Elution of reference IDTP antiserum over a column containing mycelium C-ASWS coupled to Sepharose 4B completely adsorbed precipitin antibody; i.e., reactivity in the IDTP was demonstrable in the column eluate but not in the column effluent fraction. The antigenic composition of C-ASWS extracts was evaluated and compared with that of CDN by two-dimensional immunoelectrophoresis against burro anti-CDN. The results established that both mycelium and spherule C-ASWS contain antigenic determinants in common with only one antigen present in CDN. The latter, designated antigen 2, is a large polymer which is predominant among the antigenic components in CDN. On a dry weight comparison, antigen 2 determinants were most concentrated in spherule C-ASWS, followed by mycelium C-ASWS and reference IDTP antigen. The finding that C-ASWS extracts are reactive with IgM tube precipitin antibody and are antigenically identical to antigen 2 in CDN suggests that antigen 2 is the biologically active component of CDN in tube precipitin assays.

Cell Wall

Detection of coccidioidal antibodies by 33-kDa spherule antigen, Coccidioides EIA, and standard serologic tests in sera from patients evaluated for coccidioidomycosis.

During a 9-month study of patients being evaluated for coccidioidomycosis, 1 or more serum samples were obtained from 138 patients with an illness suggestive of recent infection. In this group, standard immunodiffusion tests of unconcentrated sera were positive for 25; 49 additional patients had at least 1 reactive test result by newer enzyme-linked serologic tests. At least 11 of these 49 patients had coccidioidomycosis as determined by culture or subsequent standard serologic tests. Patients with coccidioidomycosis identified only by newer tests had fewer or milder clinical abnormalities than did patients in whom the disease was detected by standard tests. For 31 other patients with illness of a chronic or undetermined duration, newer tests detected only 10 more than the 18 identified by standard tests, suggesting that later in the course of illness, standard testing gains in sensitivity for coccidioidal infection.

Antibodies, Fungal

Stability of hybridization activity of Coccidioides immitis in live and heat-killed frozen cultures tested by AccuProbe Coccidioides immitis culture identification test.

Frozen hyphal suspensions of Coccidioides immitis were evaluated for suitability as positive control cultures in the AccuProbe C. immitis culture identification test. The genetic probe hybridization activity of heat-killed and viable frozen cultures, stored at -20 and -70 degrees C and tested over a 10-month period, was compared to that of a freshly grown culture, and the results were evaluated based upon the manufacturer's established positive and negative photometric light unit (PLU) cutoff values. All C. immitis suspensions produced positive hybridization values well above the positive and negative cutoff values, and no significant decrease in hybridization activity was observed with the frozen cultures after 10 months of storage. The frozen, heat-killed suspensions produced PLU values with less variability (coefficient of variation, 8% over 10 months than the fresh or frozen viable cultures and were deemed the most stable and sale form of positive control material to use.

Coccidioides

Coccidioidal antigen reactive CD4+ T-lymphocytes in the cerebrospinal fluid in coccidioides immitis meningitis.

CSF lymphocytes from patients with Coccidioides immitis meningitis exhibited a significant antigen-specific response to in vitro stimulation with C. immitis antigens. In some patients, lesser responses to control antigens (Candida and PPD) were also detected. Antigen-specific responses by CSF lymphocytes were seen early in the course of this disease as well as several years after patients had entered remission. When compared to CSF cells, the response of autologous peripheral blood mononuclear cells was similar but of a much smaller magnitude and at times undetectable. Fluorescence activated cell sorting revealed an increased percentage of CD3+ (T-cells), CD4+ (helper/inducer) and CD3+/HLA-DR+ (activated T-cell) cells in the CSF of C. immitis meningitis patients compared to their blood. Most of the antigen-specific proliferative response resided in the CD4+ lymphocyte subset. CSF T-cell proliferation assays may have a role in the diagnosis of C. immitis meningitis.

Adolescent

Suppression of T-lymphocyte response by Coccidioides immitis antigen.

Intravenous injection of BALB/c mice with coccidioidin or an alkali-soluble cell wall extract of Coccidioides immitis mycelia resulted in the induction of a splenic cell population(s) that suppressed delayed-type hypersensitivity response to coccidioidal antigen. To determine whether the levels of C. immitis antigen produced during the course of active coccidioidal disease might also cause suppression of T-lymphocyte response, BALB/c mice were infected by intranasal instillation of arthroconidia, and 2 weeks later, their sera were evaluated for suppression of T-lymphocyte response in syngeneic recipients. Intravenous transfer of sera, which were shown to contain high levels of coccidioidal antigen by an enzyme-linked immunoadsorbent assay, suppressed the delayed-type hypersensitivity response of recipients to immunization with coccidioidin. Solid-phase immunoadsorption of the sera with goat antibodies to C. immitis antigens removed the suppressive component(s). To determine whether the suppressive effect of circulating coccidioidal antigen(s) was associated with the activation of a splenic suppressor cell(s), as was observed in mice injected intravenously with coccidioidal antigen, spleen cell lysates were prepared from infected donors, and after filtration to remove viable fungi, the lysates were transferred to syngeneic mice. Recipients of lysates from infected but not noninfected donors were suppressed in their response to immunization with coccidioidin. Collectively, these results provide evidence that depressed T-cell responses observed in coccidioidomycosis are associated with, and may be attributable to, the activation of a suppressor cell or factor by circulating C. immitis antigens.

Animals

Experimental induction of anergy to coccidioidin by antigens of Coccidioides immitis.

Failure to react to coccidioidin (anergy) often occurs in patients with disseminated coccidioidomycosis. One possible reason may be desensitization by excessive amounts of antigen. This was studied experimentally by injection of soluble and hyphal antigens of Coccidioides immitis into coccidioidin- and tuberculin-sensitive guinea pigs. Guinea pigs sensitized by injection of killed hyphal cells of C. immitis in complete Freund adjuvant were subsequently injected daily either with soluble coccidioidal antigen administered intraperitoneally or with hyphal antigen administered either subcutaneously or intraperitoneally. Gradual loss of cutaneous reactivity to coccidioidin occurred, but the reactivity to tuberculin remained unimpaired. The rapidity of desensitization was roughly proportional to the dose of antigen with desensitization occurring as early as 6 days after beginning injections. This anergic state was temporary, and reactivity returned several days after discontinuing injection of antigen. Injection of coccidioidal antigen led to production of coccidioidal complement-fixing antibody, but there was no consistent relationship between the antibody titer and state of cutaneous reactivity to coccidioidin. Peritoneal exudate or pulmonary alveolar cells from desensitized animals migrated freely in the presence of coccidioidin but were inhibited in the presence of tuberculin. Heat treatment did not impair the capacity of the soluble or hyphal antigen to induce anergy, thus suggesting that the antigen active in complement fixation was perhaps not involved in desensitization. Polysaccharide obtained by ethanol precipitation of dialyzed coccidioidin failed to induce anergy. Dialysis of the soluble coccidioidal antigen caused the loss of the desensitizing activity. Thus, specific desensitization could be induced by administration of large doses of coccidioidal antigen but dialyzable components appear important in this desensitization.

Animals

Use of a recombinant Coccidioides immitis complement fixation antigen-chitinase in conventional serological assays.

The coccidioidal complement fixation (CF) antigen has been cloned previously, and the fusion protein has been expressed in Escherichia coli. The recombinant CF (rCF) antigen was affinity purified by adsorption-desorption to chitin, and its reactivity was studied by using sera containing coccidioidal antibodies. The affinity-purified rCF antigen formed a line of identity with an immunodiffusion (ID) CF reference antigen (coccidioidin) derived from mycelial-phase Coccidioides immitis and was reactive with human, canine, and equine sera containing coccidioidal antibody. The affinity-purified rCF antigen yielded no detectable reaction with Blastomyces of Histoplasma antiserum by ID. The affinity-purified rCF antigen fixed complement with positive human sera and, even when used at lower concentrations, yielded titers comparable to those obtained with the coccidioidin. The reactivity of the affinity-purified rCF antigen was further evaluated by enzyme immunoassay, in which it manifested good sensitivity (96.9%) and specificity (100%) when evaluated with 43 human patients' sera. Thus, the affinity-purified rCF antigen has yielded reactions comparable to those of crude coccidioidal antigens in conventional CF, IDCF, and enzyme immunoassay.

Animals

Development of dermal hypersensitivity to coccidioidal antigens associated with repeated skin testing.

Four antigens prepared from Coccidioides immitis were found to evoke no dermal reactions in 1,245 volunteers on first testing, but 2 months later, upon retesting, 18.6% of the subjects reacted to 1 or more of the antigens. In no subject did other findings indicate an intercurrent coccidioidal infection. Conversion of a skin test to reactive significantly (p less than 0.018) increased with subject age. No association was found with either years of residence within areas endemic for C. immitis or occupational exposure, associations that would be expected if conversion was due to latent hypersensitivity from a prior coccidioidal infection. Possible explanations for our findings include either boosting of immunity to a noncoccidioidal stimulus or primary sensitization from the skin testing itself. Until this phenomena is understood more fully, physicians should be reluctant to accept interval conversion of coccidioidal skin tests as a means of diagnosing recent coccidioidal infection.

Adolescent

Unusual manifestation of Coccidioides immitis infection.

Cavitary pulmonary disease secondary to coccidioidomycosis occurs in endemic areas of the southwestern United States. Significant hemoptysis requiring pulmonary resection may develop in patients with cavitary lesions. In rare instances hemoptysis may be due to the development of a fungus ball within the cavity, and such mycetomas may contain spherule and mycelial forms of Coccidioides immitis. A patient with a documented coccidioidal cavity who had hemoptysis is described in this report. Chest radiograph revealed a fungus ball within a left lower lobe cavity. The patient underwent left lower lobectomy and recovered without complications. Examination of the resected left lower lobe disclosed a cavity containing a fungus ball comprised of mycelial and spherule forms of Coccidioides immitis. A review of the literature found three reports of biphasic growth of this condition within a coccidioidomycosis cavity and two additional cases of radiographically diagnosed coccidioidal mycetoma. Discussion of the potentially contagious nature, the medical and surgical management, and the prognosis of coccidioidal mycetoma form the basis of this report.

Adult

Interaction of human peripheral blood mononuclear cells with Coccidioides immitis arthroconidia.

We explored the in vitro interaction of human peripheral blood mononuclear cells with the arthroconidial stage of the fungus Coccidioides immitis. Fresh peripheral blood monocytes in an adherent monolayer were capable of ingesting C. immitis. Further, peripheral blood monocytes from either skin-test-positive or skin-test-negative donors significantly decreased the in vitro growth of C. immitis when coccidioidal arthroconidia were incubated with monocytes. Peripheral blood mononuclear cells also reduced fungal incorporation of the chitin precursor N-acetyl glucosamine. Cell fractions consisting predominantly of monocytes were significantly more active in this regard than fractions containing predominantly lymphocytes. Moreover, this activity was independent of the coccidioidal skin-test status of the donor. We conclude that human fresh peripheral blood mononuclear cells are able to phagocytize C. immitis arthroconidia and have the ability to inhibit its growth in vitro. That these abilities are independent of the immune status of the donor supports the possibility that the peripheral blood monocyte may contribute to the early defense against initial coccidioidal infection.

Acetylglucosamine

Extraction of serologic and delayed hypersensitivity antigens from spherules of Coccidioides immitis.

We have used an aqueous toluene extraction procedure to obtain antigens from mature spherules of Coccidioides immitis. This extract contained many antigens as determined by immunoblotting and two-dimensional immunoelectrophoretic studies. These included antigens with specificity for tube precipitin-type antibodies having molecular weights greater than or equal to 100 KDa. The extract also displayed lymphocyte-transforming activity when tested on human peripheral blood mononuclear leukocytes from donors who react to coccidioidal skin tests but elicited no such stimulation of cells from persons whose coccidioidal skin tests were nonreactive. At high concentrations of the extract, lymphocyte transformation did not occur, a finding that could not be explained by nonspecific toxicity. When gel filtration was employed to separate antigens by size, tube precipitin-like activity and specific coccidioidal delayed-type hypersensitivity displayed overlap, although only the latter activity was apparent in lower molecular weight pools.

Animals

Delayed-type hypersensitivity responses to a cell wall fraction of the mycelial phase of Coccidioides immitis.

A skin test-active fraction was isolated from the mycelial-phase cell walls of Coccidioides immitis. This alkali-soluble, water-soluble antigen (C-ASWS) elicited positive reactions in 22 of 24 (92%) of the Coccidioides-sensitized guinea pigs whereas only 14 (54%) of the same guinea pigs reacted to commercial coccidioidin (BioCox). None of the 21 Histoplasma-sensitized guinea pigs cross-reacted with the C-ASWS antigen. Footpad tests in mice actively infected with Coccidioides further established the efficacy of the C-ASWS antigen in eliciting a delayed-type hypersensitivity response. One-microgram doses of C-ASWS produced reactions comparable to 100-mug doses of nondialyzable coccidioidin (Smith's lot 64 D4). The C-ASWS fractions isolated from three different C. immitis strains showed similar reactivity in terms of the number of positive reactions produced in Coccidioides-sensitized guinea pigs. However, the induration responses (diameter in millimeters) elicited by the C-ASWS fraction of one strain were significantly less than those elicited by the C-ASWS fractions of the other two C. immitis strains.

Administration, Intranasal

An immunoreactive apoglycoprotein purified from Coccidioides immitis.

Deglycosylation of glycoproteins in a lysate of spherules of Coccidioides immitis has permitted purification and partial characterization of a proline-rich pronase-sensitive antigen. Moreover, soluble antigen specifically stimulated lymphocytes from persons with dermal delayed-type hypersensitivity to coccidioidal antigens. When related to reference coccidioidin by tandem two-dimensional immunoelectrophoresis, the antigen fused in the anodal region with a specific reference antigen (antigen 2). It did not show identity with coccidioidal antigens used in conventional serologic assays. Although immunoblots of the purified protein with monospecific rabbit antiserum showed a single antigen at 33 kDa, the parent spherule lysate bound the same antibody in a broad band between 70 and greater than 200 kDa, which could be explained by microheterogeneity of glycosylation. Immunoelectron microscopy using affinity-purified human antibodies localized the antigen to the cell wall and internal septa of spherules. These findings suggest that the apoglycoprotein may be important in human immune responses to coccidioidal infection.

Antigens, Fungal

Killing of Coccidioides immitis by human peripheral blood mononuclear cells.

The ability of human peripheral blood mononuclear cells (MNL) obtained from healthy donors to kill the fungus Coccidioides immitis was examined in vitro with an assay that uses a single fungal particle per well. MNL killed 25.0% +/- 3.5% of a coccidioidal arthroconidial target, compared with the 4.7% +/- 2.9% killed by polymorphonuclear leukocytes obtained from the same donors (P = 0.012). Arthroconidial killing by MNL was not dependent on donor delayed dermal hypersensitivity to spherulin. Killing of another fungal target, Candida glabrata, was not significantly different between MNL and polymorphonuclear leukocytes (P = 0.783). Depletion of monocytes from MNL with Sephadex G-10 resulted in a significant reduction in arthroconidial killing (21.4% +/- 13.6% versus 2.4% +/- 3.4%; P = 0.025), while enrichment of monocytes by Percoll density gradient centrifugation or plastic adherence resulted in significantly increased arthroconidial killing compared with that by MNL (P = 0.005 and 0.001, respectively). Killing of 96-h spherules by MNL was 7.3% +/- 3.1%, significantly less than the 21.4% +/- 2.8% killing of arthroconidia in the same experiments (P = 0.016). Incubation of MNL with human recombinant gamma interferon or tumor necrosis factor alpha did not result in increased MNL killing of coccidioidal arthroconidia under various conditions. These results suggest that MNL have an inherent ability to kill coccidioidal arthroconidia in vitro which is not dependent on prior host exposure to C. immitis. This activity appears to reside in peripheral blood monocytes.

Coccidioides