Biomedical subjects

C W Hallahan

Publications and source records attributed to C W Hallahan.

16 recordsLinked to original sources

PubMed2000

CD40 ligand trimer and IL-12 enhance peripheral blood mononuclear cells and CD4+ T cell proliferation and production of IFN-gamma in response to p24 antigen in HIV-infected individuals: potential contribution of anergy to HIV-specific unresponsiveness.

It has been suggested that CD4+ T cell proliferative responses to HIV p24 Ag may be important in the control of HIV infection. However, these responses are minimal or absent in many HIV-infected individuals. Furthermore, while in vitro and in vivo responses to non-HIV recall Ags improve upon administration of highly active antiretroviral therapy, there does not appear to be a commensurate enhancement of HIV-specific immune responses. It is possible that CD4+ p24-specific T cells are deleted early in the course of infection. However, it is also possible that a discrete unresponsiveness, or anergy, contributes to the lack of proliferation to p24. To evaluate the possible contribution of unresponsiveness to the lack of CD4+ T cell proliferation to p24 in HIV-infected individuals, we attempted to overcome unresponsiveness. CD40 ligand trimer (CD40LT) and IL-12 significantly increased PBMC and CD4+ T cell proliferative responses to p24 Ag in HIV-infected, but not uninfected, individuals. No increase in proliferative response to CMV Ag was observed. CD40LT exerted its effect through B7-CD28-dependent and IL-12- and IL-15-independent mechanisms. Finally, the increase in proliferation with CD40LT and IL-12 was associated with an augmented production of IFN-gamma in most, but not all, individuals. These data suggest the possible contribution of HIV-specific unresponsiveness to the lack of CD4+ T cell proliferation to p24 Ag in HIV-infected individuals and that clonal deletion alone does not explain this phenomenon. They also indicate the potential for CD40LT and IL-12 as immune-based therapies for HIV infection.

Adjuvants, Immunologic↗

PubMed2000

Maintenance of large numbers of virus-specific CD8+ T cells in HIV-infected progressors and long-term nonprogressors.

The virus-specific CD8+ T cell responses of 21 HIV-infected patients were studied including a unique cohort of long-term nonprogressors with low levels of plasma viral RNA and strong proliferative responses to HIV Ags. HIV-specific CD8+ T cell responses were studied by a combination of standard cytotoxic T cell (CTL) assays, MHC tetramers, and TCR repertoire analysis. The frequencies of CD8+ T cells specific to the majority of HIV gene products were measured by flow cytometric detection of intracellular IFN-gamma in response to HIV-vaccinia recombinant-infected autologous B cells. Very high frequencies (0.8-18.0%) of circulating CD8+ T cells were found to be HIV specific. High frequencies of HIV-specific CD8+ T cells were not limited to long-term nonprogressors with restriction of plasma virus. No correlation was found between the frequency of HIV-specific CD8+ T cells and levels of plasma viremia. In each case, the vast majority of cells (up to 17.2%) responded to gag-pol. Repertoire analysis showed these large numbers of Ag-specific cells were scattered throughout the repertoire and in the majority of cases not contained within large monoclonal expansions. These data demonstrate that high numbers of HIV-specific CD8+ T cells exist even in patients with high-level viremia and progressive disease. Further, they suggest that other qualitative parameters of the CD8+ T cell response may differentiate some patients with very low levels of plasma virus and nonprogressive disease.

Adult↗

PubMed2000

HLA B*5701 is highly associated with restriction of virus replication in a subgroup of HIV-infected long term nonprogressors.

A unique cohort of HIV-1-infected long term nonprogressors (LTNP) with normal CD4(+) T cell counts and <50 copies/ml of plasma were prospectively recruited for study. HLA typing revealed a dramatic association between the HLA B*5701 class I allele and nonprogressive infection [85% (11 of 13) vs. 9.5% (19 of 200) in progressors; P < 0. 001]. Antigen-specific CD8(+) T cells were enumerated by flow cytometric detection of intracellular IFN-gamma in response to HIV antigens and HLA B*57-gag tetramer staining. No quantitative differences in the total HIV-specific CD8(+) T cell responses were observed between B*57(+) LTNP and five B*57(+) progressors (P = 0.4). Although similar frequencies of peptide specific CD8(+) T cells were also found, the gag-specific CD8(+) T cell response in the LTNP group was highly focused on peptides previously shown to be B*57-restricted. These findings indicate that, within this phenotypically and genotypically distinct cohort, a host immune factor is highly associated with restriction of virus replication and nonprogressive disease. They also strongly suggest a mechanism of virus specific immunity that directly operates through the B*5701 molecule. Further characterization of qualitative differences in the virus-specific responses that distinguish HLA B*57(+) LTNP from progressors may ultimately define mechanisms of effective immune mediated restriction of virus replication.

Alleles↗

PubMed2000

Resistance to replication of human immunodeficiency virus challenge in SCID-Hu mice engrafted with peripheral blood mononuclear cells of nonprogressors is mediated by CD8(+) T cells and associated with a proliferative response to p24 antigen.

High levels of resistance to challenge with human immunodeficiency virus type 1 SF162 were observed in animals engrafted with peripheral blood mononuclear cells of four long-term nonprogressors (LTNPs). Resistance was abrogated by depletion of CD8(+) T cells in vivo and was observed only in LTNPs with proliferative responses to p24. In a subgroup of nonprogressors, CD8(+) T cells mediated restriction of challenge viruses, and this response was associated with strong proliferative responses to p24 antigen.

Animals↗

PubMed1999

Effect of interleukin-2 on the pool of latently infected, resting CD4+ T cells in HIV-1-infected patients receiving highly active anti-retroviral therapy.

The size of the pool of resting CD4+ T cells containing replication-competent HIV in the blood of patients receiving intermittent interleukin (IL)-2 plus highly active anti-retroviral therapy (HAART) was significantly lower than that of patients receiving HAART alone. Virus could not be isolated from the peripheral blood CD4+ T cells in three patients receiving IL-2 plus HAART, despite the fact that large numbers of resting CD4+ T cells were cultured. Lymph node biopsies were done in two of these three patients and virus could not be isolated. These results indicate that the intermittent administration of IL-2 with continuous HAART may lead to a substantial reduction in the pool of resting CD4+ T cells that contain replication-competent HIV.

Anti-HIV Agents↗

PubMed1999

Both memory and CD45RA+/CD62L+ naive CD4(+) T cells are infected in human immunodeficiency virus type 1-infected individuals.

Cellular activation is critical for the propagation of human immunodeficiency virus type 1 (HIV-1) infection. It has been suggested that truly naive CD4(+) T cells are resistant to productive HIV-1 infection because of their constitutive resting state. Memory and naive CD4(+) T-cell subsets from 11 HIV-1-infected individuals were isolated ex vivo by a combination of magnetic bead depletion and fluorescence-activated cell sorting techniques with stringent criteria of combined expression of CD45RA and CD62L to identify naive CD4(+) T-cell subsets. In all patients HIV-1 provirus could be detected within naive CD45RA+/CD62L+ CD4(+) T cells; in addition, replication-competent HIV-1 was isolated from these cells upon CD4(+) T-cell stimulation in tissue cultures. Memory CD4(+) T cells had a median of fourfold more replication-competent virus and a median of sixfold more provirus than naive CD4(+) T cells. Overall, there was a median of 16-fold more integrated provirus identified in memory CD4(+) T cells than in naive CD4(+) T cells within a given patient. Interestingly, there was a trend toward equalization of viral loads in memory and naive CD4(+) T-cell subsets in those patients who harbored CXCR4-using (syncytium-inducing) viruses. Within any given patient, there was no selective usage of a particular coreceptor by virus isolated from memory versus naive CD4(+) T cells. Our findings suggest that naive CD4(+) T cells may be a significant viral reservoir for HIV, particularly in those patients harboring CXCR4-using viruses.

Adult↗

PubMed1996

Cyclophosphamide-induced cystitis and bladder cancer in patients with Wegener granulomatosis.

OBJECTIVE: To describe the incidence of, clinical manifestations of, and risk factors for cyclophosphamide-induced urinary bladder toxicity in patients treated for nonmalignant disease. DESIGN: Retrospective analysis of patients followed at the National Institutes of Allergy and Infectious Diseases from 1967 to 1993. SETTING: The Warren G. Magnuson Clinical Center of the National Institutes of Health (NIH). PATIENTS: 145 patients who received cyclophosphamide for the treatment of Wegener granulomatosis and were followed for 0.5 to 27 years (median, 8.5 years), for a total of 1333 patient-years. MEASUREMENTS: Clinical characteristics, cystoscopic findings, results of cytologic examination of urine, surgical pathology, and total dose and duration of cyclophosphamide therapy were recorded and analyzed using a computer-based information retrieval system. RESULTS: Nonglomerular hematuria occurred in 73 of 145 patients treated with cyclophosphamide (50%). Sixty of the 73 patients with nonglomerular hematuria (82%) had cystoscopy at the NIH. Forty-two of the 60 patients (70%) who had cystoscopy had macroscopic changes consistent with cyclophosphamide-induced bladder injury. Seven patients (5%) developed transitional-cell carcinoma of the urinary bladder. In 6 of these 7 patients, the total cumulative cyclophosphamide dose exceeded 100 g, and the cumulative duration of cyclophosphamide therapy exceeded 2.7 years. Before they were given a diagnosis of bladder cancer, all 7 patients had had one or more episodes of microscopic or gross nonglomerular hematuria. In contrast, none of the 72 patients who had never had nonglomerular hematuria developed bladder cancer. Cox proportional hazards regression analysis showed that only microscopic nonglomerular hematuria was a significant risk factor for the development of bladder cancer (P < 0.01). CONCLUSION: Long-term oral cyclophosphamide therapy is associated with substantial urotoxicity, including the development of transitional-cell carcinoma of the urinary bladder. In this cohort of patients, the estimated incidence of bladder cancer after the first exposure to cyclophosphamide was 5% at 10 years and 16% at 15 years. Nonglomerular hematuria was a frequent manifestation of cyclophosphamide-induced cystitis, and it identified a subgroup of patients at high risk for the development of bladder cancer.

Aged↗

PubMed1996

Clinical features and therapeutic management of subglottic stenosis in patients with Wegener's granulomatosis.

OBJECTIVE: To determine the clinical features and optimal treatment of subglottic stenosis (SGS) in patients with-Wegener's granulomatosis (WG). METHODS: Review of 43 patients with SGS and treatment of 20 patients with intratracheal dilation-glucocorticoid injection therapy. RESULTS: SGS developed in 43 of 189 patients with WG who were followed up at the National Institutes of Health Clinical Center. The diagnosis of SGS occurred in the absence of other features of active. WG in 21 of 43 patients (49%). In 21 patients (49%), SGS began while the patient was receiving systemic immunosuppressive therapy for disease activity involving other sites. Tracheostomy was required in 10 of 18 patients (56%) who were treated with systemic immunosuppressive therapy. In 20 patients treated with intratracheal therapy, none required tracheostomy and 6 with previous tracheostomies were decannulated. CONCLUSION: SGS often occurs independently of other features of active WG and is frequently unresponsive to systemic immunosuppressive therapy. Intratracheal dilation-injection therapy provides a safe and effective treatment for WG-associated SGS and, in the absence of major organ disease activity, should be used without concomitant systemic immunosuppressive agents.

Adult↗

PubMed1995

An analysis of forty-two Wegener's granulomatosis patients treated with methotrexate and prednisone.

OBJECTIVE: To determine the efficacy of low-dose methotrexate (MTX) plus prednisone in the treatment of Wegener's granulomatosis (WG). METHODS: An open-label study of weekly low-dose MTX plus prednisone for the treatment of WG was performed. Forty-two patients who did not have immediately life-threatening disease were enrolled into the study. Outcome was determined by clinical characteristics and pathologic, laboratory, and radiographic findings. RESULTS: Weekly administration of MTX and prednisone resulted in remission of disease in 30 of the 42 patients (71%). The median time to remission was 4.2 months. The estimated median time to relapse for all patients in whom remission was achieved was 29 months. Eight patients who had relapses were treated with a second course of MTX plus prednisone, and a second remission was induced in 6 of the 8 (75%). CONCLUSION: Weekly low-dose MTX was shown in this study to be an acceptable alternative form of therapy for selected patients with WG who do not have immediately life-threatening disease or who have developed serious cyclophosphamide-associated toxicity.

Administration, Oral↗

PubMed1995

Cutaneous pathology in Wegener's granulomatosis. A clinicopathologic study of 75 biopsies in 46 patients.

While no cutaneous lesion is specific for Wegener's granulomatosis (WG), several histopathologic entities, including leukocytoclastic vasculitis and necrotizing granulomatous inflammation, are characteristic. This report details the histopathologic features of 75 cutaneous biopsies from 46 patients with WG. Biopsies were subdivided into histologic groups that included leukocytoclastic vasculitis (31%), granulomatous inflammation (GI) (19%), nonspecific ulceration (4%), superficial dermal and epidermal necrosis without inflammation (2.7%), erythema nodosum (2.7%), granuloma annulare (1%), chronic inflammation (31%), and acute inflammatory lesions without vasculitis (9%). No convincing example of granulomatous vasculitis was observed. The histopathologic subgroups were correlated with clinical features, and the results were compared with those from a control group of 82 WG patients with no skin involvement. We found that the histopathologic subgroups of leukocytoclastic vasculitis and granulomatous inflammation correlated with different clinical courses. Patients with leukocytoclastic vasculitis developed WG at an earlier age (median age, 30 years) than did the control group (median age, 45 years). Leukocytoclastic vasculitis developed shortly after onset of WG (median, 15 months vs. 35 months for patients with nonspecific chronic inflammation). All lesions occurred during active disease. Active disease with leukocytoclastic vasculitis was associated with a mean erythrocyte sedimentation rate twice that of active disease in the same patient when leukocytoclastic vasculitis was absent. The patients with leukocytoclastic vasculitis had more rapidly progressive and widespread WG than patients with granulomatous skin lesions or patients without skin lesions. A marked excess of joint and musculoskeletal symptoms and renal disease was seen in patients with leukocytoclastic vasculitis. Patients with granulomatous inflammation also developed WG at an early age (median age, 30 years) when compared with the control group. Cutaneous granulomatous lesions also developed shortly after presentation (median, 12 months). Only 64% of granulomatous biopsies were from patients with active disease. These patients frequently had neither renal nor pulmonary manifestations of WG, and their disease progressed at a slower rate than that of the patients with leukocytoclastic vasculitis. These findings suggest that the cutaneous lesions characteristic of WG may correlate with the activity, distribution, and course of the disease.

Adolescent↗

PubMed1994

Takayasu arteritis.

OBJECTIVE: To evaluate prospectively the clinical features, angiographic findings, and response to treatment of patients with Takayasu arteritis. DESIGN: 60 patients with Takayasu arteritis were studied at the National Institute of Allergy and Infectious Diseases between 1970 and 1990 and were followed for 6 months to 20 years (median follow-up, 5.3 years). MEASUREMENTS: Data on clinical features, angiographic and laboratory findings, disease course, and response to therapy were all recorded and stored in a computer-based retrieval system. SETTING: The Warren Magnuson Clinical Center of the National Institutes of Health. RESULTS: In our series of patients, Takayasu arteritis was more common in Asian persons compared with persons from other racial groups. Females (97%) were most frequently affected. The median age at disease onset was 25 years. Juveniles had a delay in diagnosis that was about four times that of adults. The clinical presentation ranged from asymptomatic to catastrophic with stroke. The most common clinical finding was a bruit. Hypertension was most often associated with renal artery stenosis. Only 33% of all patients had systemic symptoms on presentation. Sixty-eight percent of patients had extensive vascular disease; stenotic lesions were 3.6-fold more common than were aneurysms (98% compared with 27%). The erythrocyte sedimentation rate was not a consistently reliable surrogate marker of disease activity. Surgical bypass biopsy specimens from clinically inactive patients showed histologically active disease in 44% of patients. Although clinically significant palliation usually occurred after angioplasty or bypass of severely stenotic vessels, restenosis was common. Medical therapy was required for 80% of patients, whereas 20% had monophasic self-limiting disease. Immunosuppressive treatment with glucocorticoids alone or in combination with a cytotoxic agent failed to induce remission in one fourth of patients; about half of those who achieved remission later relapsed. CONCLUSIONS: In North America, Takayasu arteritis is a rare disease. It is heterogeneous in presentation, progression, and response to therapy. Current laboratory markers of disease activity are insufficiently reliable to guide management. Most patients require repeated and, at times, prolonged courses of therapy. Although mortality was low, substantial morbidity occurred in most patients.

Adolescent↗

PubMed1993

Limited prognostic value of changes in antineutrophil cytoplasmic antibody titer in patients with Wegener's granulomatosis.

OBJECTIVE: To assess the correlation and prognostic value of antineutrophil cytoplasmic antibody (cANCA) titers with disease activity in patients with Wegener's granulomatosis (WG). METHODS: One hundred six patients with WG had serum ANCA determinations; 72 had serial titers obtained routinely at 1-3-month intervals. One hundred twelve subjects (19 of whom were healthy donors) served as controls. All serum samples were tested for cANCA by an indirect immunofluorescence technique. A prospective analysis of disease activity and cANCA values was performed. Disease activity was assessed according to clinical, laboratory, radiographic, and histopathologic findings. RESULTS: Positivity for cANCA was a sensitive (88%) marker of active WG. However, changes in serial titers temporally correlated with a change in disease status in only 64% of patients. Furthermore, an increase in the cANCA titer preceded clinical exacerbation of disease in only 24% of patients who had been in remission or had low-grade, smoldering disease. CONCLUSION: A rise in cANCA titer alone should not be considered adequate evidence of an impending clinical exacerbation, and therefore does not justify initiating or increasing immunosuppressive therapy.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1993

Limited prognostic value of changes in antineutrophil cytoplasmic antibody titers in patients with Wegener's granulomatosis.

One hundred and six patients with Wegener's granulomatosis (WG) were studied for the presence of antineutrophil cytoplasmic antibodies (ANCA). In 53 patients serial ANCA determinations were obtained. C-ANCA positivity was a sensitive (88%) marker of active WG. However, changes in serial titers were temporally concordant with a change in disease status in only 55% of patients. Furthermore, a rise in c-ANCA titer preceded clinical exacerbation of disease in only 24% of patients who had been in remission or had low grade, smoldering disease. A rise in c-ANCA titer alone should not be considered a priori evidence of impending relapse, and does not justify modification of immunosuppressive therapy.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1993

Wegener granulomatosis in children and adolescents: clinical presentation and outcome.

We prospectively studied and compared clinical features, treatment, course of illness, and long-term morbidity and mortality rates for Wegener granulomatosis in 23 childhood-onset patients with those of 135 adult-onset patients who were studied concurrently. Treatment was usually provided with glucocorticoids and cyclophosphamide. The mean follow-up period was 8.7 years for childhood-onset and 7.6 years for adult-onset Wegener granulomatosis. Most aspects of Wegener granulomatosis were similar in childhood-onset and adult-onset patients. Permanent morbidity from disease occurred in 86% of both groups. However, some features were significantly different. Wegener granulomatosis in childhood-onset patients was complicated five times more often by subglottic stenosis and twice as often by nasal deformity. Treatment-related permanent morbidity occurred in 22% of childhood-onset patients and 45% of adult-onset patients. After similar periods of cyclophosphamide therapy and follow-up, cyclophosphamide-related malignancies were less likely (0% vs 11%) to have developed in childhood-onset patients. Although 89% of patients treated with glucocorticoids and cyclophosphamide had remission, prolonged delay in achieving remission and relapses led in both patient groups to freedom from active disease for approximately 50% of the total patient-years. As a result, morbidity was substantial and has led to comparative studies of alternative therapies.

Adolescent↗

PubMed1992

Wegener granulomatosis: an analysis of 158 patients.

OBJECTIVE: To prospectively study the clinical features, pathophysiology, treatment and prognosis of Wegener granulomatosis. DESIGN: Of the 180 patients with Wegener granulomatosis referred to the National Institute of Allergy and Infectious Diseases during the past 24 years, 158 have been followed for 6 months to 24 years (a total of 1229 patient-years). MEASUREMENTS: Characteristics of clinical presentation, surgical pathology, course of illness, laboratory and radiographic findings, and the results of medical and surgical treatment have been recorded in a computer-based information retrieval system. SETTING: The Warren Magnuson Clinical Center of the National Institutes of Health. MAIN RESULTS: Men and women were equally represented; 97% of patients were white, and 85% were more than 19 years of age. The mean period of follow-up was 8 years. One hundred and thirty-three patients (84%) received "standard" therapy with daily low-dose cyclophosphamide and glucocorticoids. Eight (5.0%) received only low-dose cyclophosphamide. Six (4.0%) never received cyclophosphamide and were treated with other cytotoxic agents and glucocorticoids. Ten patients (6.0%) were treated with only glucocorticoids. Ninety-one percent of patients experienced marked improvement, and 75% achieved complete remission. Fifty percent of remissions were associated with one or more relapses. Of 99 patients followed for greater than 5 years, 44% had remissions of greater than 5 years duration. Thirteen percent of patients died of Wegener granulomatosis, treatment-related causes, or both. Almost all patients had serious morbidity from irreversible features of their disease (86%) or side effects of treatment (42%). CONCLUSIONS: The course of Wegener granulomatosis has been dramatically improved by daily treatment with cyclophosphamide and glucocorticoids. Nonetheless, disease- and treatment-related morbidity is often profound. Alternative forms of therapy have not yet achieved the high rates of remission induction and successful maintenance that have been reported with daily cyclophosphamide treatment. Despite continued therapeutic success with cyclophosphamide, our long-term follow-up of patients with Wegener granulomatosis has led to increasing concerns about toxicity resulting from prolonged cyclophosphamide therapy and has encouraged investigation of other therapeutic regimens.

Adolescent↗

PubMedDate not supplied

Elucidation of the DNA synthetic cycle of Entamoeba spp. using flow cytometry and mathematical modeling.

We developed a method to study the DNA synthetic cycles of Entamoeba histolytica and Entamoeba invadens by flow cytometry (FCM) based on a preparative procedure to reduce both high levels of natural fluorescence and non-specific adsorption of fluorochromes. We modeled G1, S, and G2 phases as a series of overlapping Gaussian curves. Both E. histolytica and E. invadens displayed G1, S, and G2 proportions that are consistent with eukaryotic cell populations in exponential or stationary growth phase. Exponential phase E. histolytica populations contained a hypodiploid subset with a mass of about 20% less than the diploid value which we estimate by FCM to be 24 x 10(-14) g DNA/cell. Exponential phase E. invadens populations contained a hypodiploid subset with a mass of about 6% less than the diploid value which we estimate by FCM to be 30 x 10(-14) g DNA/cell.

Animals↗