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A radioimmunoassay for Histoplasma capsulatum variety capsulatum antigen is an important test for making the rapid diagnosis of disseminated histoplasmosis. However, the performance of this test is restricted to one laboratory because it has not been possible to make large quantities of high quality rabbit polyclonal antibody used in the test. Since monoclonal antibodies are usually produced more reliably, we attempted to make murine monoclonal antibodies against H. capsulatum var. capsulatum antigen to substitute for the rabbit polyclonal antibody in the assay. Two monoclonal antibodies, MHPA 1 and MHPA 2, were made from mice immunized with H. capsulatum antigen from the urine of two patients with disseminated histoplasmosis. MHPA 1 was IgG1, and MHPA 2 was IgM. In enzyme immunoassays, neither monoclonal antibody reacted with a panel of H. capsulatum antigens, but the polyclonal antibody did. Both monoclonal antibodies detected urinary H. capsulatum antigen in small percentages of patients with disseminated histoplasmosis who had positive radioimmunoassay results, 12.5% for MHPA 1 and 2.1% for MHPA 2. They did not detect H. capsulatum antigen in patients without histoplasmosis. These data suggest that H. capsulatum var. capsulatum antigen may have multiple epitopes. We conclude that these monoclonal antibodies react with H. capsulatum antigen, but they are unsuitable for replacing the rabbit polyclonal antibody used in the radioimmunoassay for the antigen.

purpose: The purpose of this study was to establish the effect of induction and maintenance treatment with amphotericin B on levels of Histoplasma capsulatum var. capsulatum polysaccharide antigen (HPA) in the urine and blood of patients with acquired immunodeficiency syndrome (AIDS) and disseminated histoplasmosis. patients and methods: This was a retrospective study of the effect of amphotericin B treatment on levels of HPA in the urine or serum from 70 patients with AIDS and disseminated histoplasmosis. All patients received initial intensive induction treatment with amphotericin B, and a subset continued to receive amphotericin B at less frequent intervals for maintenance therapy to prevent relapse. Treatment regimens varied in intensity and duration and specimens were obtained at irregular intervals. Urine and serum specimens were stored and retested for HPA in the same radioimmunoassay. results: HPA levels in serum decreased by at least 2 units during induction therapy in all 19 (100%) patients with initial levels of greater than or equal to 2.6 units and reverted to negative in 40.9% of those with initial levels of greater than or equal to 1.0 unit. HPA in urine decreased by at least 2 units in 84.8% and reverted to negative in 17.3% of patients. During induction treatment, HPA cleared more rapidly from serum than from urine. During maintenance treatment, HPA levels in serum decreased by at least 2 units in 100% and became negative in 66.7%. HPA in urine decreased by at least 2 units in 54.5% and reverted to negative in 20.0%. Rates of clearance of HPA from the serum and urine were similar, 0.01 unit/week compared with −0.04 unit/week, respectively, but less than rates during induction treatment. conclusions: Successful therapy of histoplasmosis with amphotericin B is associated with reduction of HPA in body fluids. Periodic measurement of HPA levels offers a method for monitoring the response to therapy and for comparing new treatments for histoplasmosis.

We sought to determine whether measurement of Histoplasma capsulatum var. capsulatum antigen concentration in tissues and blood provided a marker for antifungal effect of itraconazole in a nonlethal murine model of histoplasmosis. Treatment with itraconazole (Sporanox), in cyclodextrin, was evaluated in a pulmonary model of histoplasmosis. Mice infected with 4.0 × 107 yeast-phase organisms by endotracheal inoculation were treated with itraconazole, 1.5 mg twice daily by gavage, for 10 consecutive days, beginning on day 4 of infection. All mice were sacrificed on day 15 of infection. Blood, spleen, and lung tissues were removed for culture and quantification of antigen. Numbers of organisms were significantly lower in spleens from the treated group: 20.8 ± 41.8 vs. 65.8 ± 39.1 in the control group, P = 0.017. Numbers of organisms in lung were 9.6 ± 27.3 colonyforming units in treated versus 24.2 ± 36.3 in control animals, P = 0.267. Antigen concentrations in spleen tissue and serum were lower in treated versus control mice: spleen, 1.8 ± .6 units in treated versus 11.0 ± 2.3 in controls, P < 0.001; serum, 0.8 ± 0.2 units in treated versus 2.2 ± 1.0 units in controls, P < 0.001. Lung antigen concentrations were similar in the two groups, 19.2 ± 1.4 units in treated compared to 17.9 ± 3.0 units in control mice, P = 0.142. The cyclodextrin formulation of itraconazole (Sporanox) demonstrated antifungal activity in experimental histoplasmosis. Antigen detection was a useful marker for antifungal effect. © 1994 Wiley-Liss, inc.

To assess the accuracy of Histoplasma capsulatum variety capsulatum polysaccharide antigen testing for the identification of histoplasmosis relapse in patients with the acquired immunodeficiency syndrome (AIDS).A retrospective study using stored specimens.A referral center and several private hospitals.Twenty episodes of histoplasmosis relapse were evaluated in 17 patients with AIDS from November 1987 to August 1990. Controls included 30 patients with AIDS and histoplasmosis who did not have a relapse during maintenance therapy and who were initially tested during the same week as the patients with relapse. A second control group included seven patients with AIDS and histoplasmosis who were evaluated for relapse on 23 occasions; relapse, however, was excluded on each occasion.To avoid interassay variability, specimens were tested for H.c. var. capsulatum polysaccharide antigen with the same radioimmunoassay.The change in the H.c. var. capsulatum polysaccharide antigen level during successful as opposed to unsuccessful maintenance therapy for the prevention of histoplasmosis relapse.For the 20 episodes of relapse (17 patients), H.c. var. capsulatum antigen levels increased by at least 2 radioimmunoassay units in 12 of 14 serum specimens tested (85.7%; 95% Cl, 57.2% to 98.2%) and in 17 of 18 urine specimens tested (94.4%; Cl, 72.7% to 99.9%). Antigen levels increased in the urine or serum in 1 of 83 specimens (1.2%; CI, 0.03% to 6.6%) obtained on 56 occasions (1.8%; CI, 0.04% to 9.6%) from controls (specificity, 98.2%; CI, 90.4% to 99.96%). In three cases of relapse, antigen levels increased before clinical relapse, antigen levels increased before clinical relapse was suspected. Complement fixation titers increased by at least 2 dilutions in 4 of 11 cases (36.4%; CI, 10.9% to 69.2%) but in 0 of 9 control patients (CI, 0% to 28.3%).An increase in H.c. var. capsulatum polysaccharide antigen levels of 2 units or more strongly suggests histoplasmosis relapse. The presence of increasing titers of anti-H.c. var. capsulatum antibodies by complement fixation is less accurate for the diagnosis of relapse.

We sought to determine if Histoplasma capsulatum polysaccharide antigen (HPA) levels correlate with the extent of infection in murine of histoplasmosis. Separate groups of mice were inoculated intratracheally with varying numbers of H. capsulatum yeast cells. After 1 week, HPA levels and fungal burden (quantitative culture of lung and spleen and histopathologic stain of lung) were determined in lung and spleen, and HPA levels in serum. HPA levels, cultures and histopathological stain results of lung and spleen tissue showed a direct correlation with increasing inoculum size. HPA levels in serum also correlated with the size of inoculum. H. capsulatum antigen in lung correlated with silver stain scores of lung tissue, (R = 0.948, P less than 0.001) and with quantitative culture scores of lung, (R = 0.929, P less than 0.001). HPA levels in spleen tissue also correlated with spleen culture scores, (R = 0.724, P less than 0.001). These results indicate that determination of HPA level in serum and tissue may be a useful test in evaluating the severity of diseases as well as efficacy of antifungal therapy in histoplasmosis.

Purpose Disseminated histoplasmosis is a serious and often rapidly progressive, opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS), supporting the importance of rapid diagnostic tests. We investigated Histoplasma capsulatum polysaccharide antigen (HPA) detection, a promising new method for rapid diagnosis of histoplasmosis. Patients and methods Sixty-one cases of disseminated histoplasmosis in patients with AIDS form the basis of this report. Control cases were patients with AIDS who had other opportunistic infections and whose cultures were negative for H. capsulatum. A slightly modified radioimmunoassay procedure was used to measure the levels of HPA in urine and blood specimens. Results High levels of HPA were detected in the urine of 59 of 61 (96.7%) and the blood of 37 of 47 (78.7%) patients with AIDS complicated by disseminated histoplasmosis. Treatment with amphotericin B reduced levels of HPA in the urine in 19 of 21 (90.5%) and the serum of all 10 patients tested. HPA levels increased in the urine in all eight and in the serum in all five patients with culture-proven relapse. Conclusion In conclusion, HPA detection offers a rapid method for diagnosing disseminated histoplasmosis. Additional experience is required to establish the role of this test in monitoring the effects of treatment and in identifying relapse in patients with AIDS.

Detection of a Histoplasma capsulatum polysaccharide antigen (HPA) has proved a useful approach to diagnosis of histoplasmosis. Two sandwich enzyme-linked immunosorbent assays (ELISAs) using alkaline phosphatase (AP)- or horseradish peroxidase (HRP)conjugated antibodies were compared with solid-phase radioimmunoassay (RIA) for detection of HPA. The AP-ELISA and HRP-ELISA were each positive in 17 (89.5^o) of 19 urine specimens from patients with disseminated histoplasmosis, while the RIA was positive in 18 (94.7^0) of 19. Specimens from patients with nondisseminated histoplasmosis were positive by AP-ELISA in 8 of 32, by HRP-ELISA in 4 of 25, and by RIA in 12 of 25. Of control specimens from patients with other fungal infections, the APELISA was negative in 22 (91.7970) of 24, the HRP-ELISA in 23 (95.8^o) of 24, and the RIA in 23 (95.8^o) of 24. Reproducibilities of the AP-ELISA and HRP-ELISA were 95.1^0 and 95.1^0, respectively. Thus, AP-ELISA and HRP-ELISA appear less sensitive than RIA and may be falsely negative in specimens containing low levels of HPA.

To assess the efficacy and safety of itraconazole in preventing relapse of histoplasmosis after induction therapy with amphotericin B in patients with the acquired immunodeficiency syndrome (AIDS) and disseminated histoplasmosis.A prospective, multicenter, open-label clinical trial, with follow-up for at least 52 weeks.Tertiary care hospitals participating in a clinical investigation sponsored by the National Institutes of Allergy and Infectious Diseases (AIDS Clinical Trial Group and Mycoses Study Group).Forty-two patients with AIDS who had successfully completed induction therapy for disseminated histoplasmosis amphotericin B, at least 15 mg/kg body weight given over 4 to 12 weeks.Itraconazole, 200 mg given orally twice daily.Response to therapy, specifically prevention of histoplasmosis relapse, was the main outcome measure. Secondary end points were survival and the effect of therapy on Histoplasma capsulatum variety capsulatum antigen levels in urine and serum. Plasma itraconazole concentrations were measured to document drug absorption and compliance with therapy.The median follow-up was 109 weeks, and median survival was 98 weeks. Two relapses occurred (5%; 95% CI, 0.5% to 16%), one in a patient withdrawn from the study 18 weeks earlier and one in a patient who did not comply with the study therapy. Patients with elevated antigen levels at study entry showed clearance of antigen from urine and serum; urine specimens became negative in 43% of patients (CI, 26% to 59%), and serum specimens became negative in 75% of patients (CI, 56% to 94%). Only one patient discontinued treatment because of itraconazole toxicity (hypokalemia).Itraconazole, 200 mg twice daily, is safe and effective in preventing relapse of disseminated histoplasmosis in patients with AIDS. Antigen clearance from blood and urine correlates with clinical efficacy.