Biomedical subjects

Dean Follmann

Publications and source records attributed to Dean Follmann.

At least 19 recordsLinked to original sources

PubMed2007

Statistical methods for active extension trials.

This paper develops methods of analysis for active extension clinical trials. Under this design, patients are randomized to treatment or placebo for a period of time (period 1), and then all patients receive treatment for an additional period of time (period 2). We assume a continuous outcome is measured at baseline and at the end of the two consecutive periods. If only period 1 data is available, classic estimators of the treatment effect include the change score, analysis of covariance, and maximum likelihood (ML). We show how to extend these estimators by incorporating period 2 data which we refer to as the period 2 estimators. Under the assumption that the mean responses for treatment and placebo arms are the same at the end of period 2, the new estimators are unbiased and more efficient than estimators that ignore period 2 data. If this assumption is not met, the period 2 tests may be more powerful than period 1 tests, but the estimators are biased downward (upward) if the treatment effect during period 2 is larger (smaller) in treatment arm than the placebo arm. In general, the proposed period 2 procedure can provide an efficient way to supplement but not supplant the usual period 1 analysis.

Analysis of Variance↗

PubMed2007

Endpoints and regulatory issues in HIV vaccine clinical trials: lessons from a workshop.

A successful HIV vaccine would have a substantial impact on acquisition of infection, progression of disease among the infected, or infectiousness of the infected. Current vaccine candidates are anticipated to have their major effect on viremia, however, with the expectation that this would induce or be concordant with a reduced rate of AIDS, death, or infectiousness. Although direct assessment of disease progression or infectiousness may be impractical, available potential surrogates for these endpoints may be misleading. This article summarizes the proceedings of a National Institute of Allergy and Infectious Disease-sponsored workshop to explore the use of surrogate endpoints for licensure of an HIV vaccine. Early, medium, and late endpoints were discussed, along with challenges such as surrogate validity, the confounding effect of antiretroviral therapy initiation, and potential selection bias in the vaccine and placebo recipients who become infected. Results from 5 hypothetic HIV vaccine clinical trials with ambiguously successful results were presented to an expert panel for interpretation and discussion of next steps. Key recommendations included assessing magnitude and durability of surrogate effects, generalization across populations, and directed improvement of vaccines. Use of acquisition and a postinfection surrogate as coprimary endpoints was supported, along with use of composite endpoints and exploration of heterogeneity in vaccine efficacy by characteristics of the host and virus.

AIDS Vaccines↗

PubMed2006

Characterization of the defective interaction between a subset of natural killer cells and dendritic cells in HIV-1 infection.

In this study, we demonstrate that the in vitro interactions between a CD56(neg)/CD16(pos) (CD56(neg)) subset of natural killer (NK) cells and autologous dendritic cells (DCs) from HIV-1-infected viremic but not aviremic individuals are markedly impaired and likely interfere with the development of an effective immune response. Among the defective interactions are abnormalities in the process of reciprocal NK-DC activation and maturation as well as a defect in the NK cell-mediated editing or elimination of immature DCs (iDCs). Notably, the lysis of mature DCs (mDCs) by autologous NK cells was highly impaired even after the complete masking of major histocompatibility complex I molecules, suggesting that the defective elimination of autologous iDCs is at the level of activating NK cell receptors. In this regard, the markedly impaired expression/secretion and function of NKp30 and TNF-related apoptosis-inducing ligand, particularly among the CD56(neg) NK cell subset, largely accounts for the highly defective NK cell-mediated lysis of autologous iDCs. Moreover, mDCs generated from HIV-1 viremic but not aviremic patients are substantially impaired in their ability to secrete interleukin (IL)-10 and -12 and to prime the proliferation of neighboring autologous NK cells, which, in turn, fail to secrete adequate amounts of interferon-gamma.

Adult↗

PubMed2006

Augmented designs to assess immune response in vaccine trials.

This article introduces methods for use in vaccine clinical trials to help determine whether the immune response to a vaccine is actually causing a reduction in the infection rate. This is not easy because immune response to the (say HIV) vaccine is only observed in the HIV vaccine arm. If we knew what the HIV-specific immune response in placebo recipients would have been, had they been vaccinated, this immune response could be treated essentially like a baseline covariate and an interaction with treatment could be evaluated. Relatedly, the rate of infection by this baseline covariate could be compared between the two groups and a causative role of immune response would be supported if infection risk decreased with increasing HIV immune response only in the vaccine group. We introduce two methods for inferring this HIV-specific immune response. The first involves vaccinating everyone before baseline with an irrelevant vaccine, for example, rabies. Randomization ensures that the relationship between the immune responses to the rabies and HIV vaccines observed in the vaccine group is the same as what would have been seen in the placebo group. We infer a placebo volunteer's response to the HIV vaccine using their rabies response and a prediction model from the vaccine group. The second method entails vaccinating all uninfected placebo patients at the closeout of the trial with the HIV vaccine and recording immune response. We pretend this immune response at closeout is what they would have had at baseline. We can then infer what the distribution of immune response among placebo infecteds would have been. Such designs may help elucidate the role of immune response in preventing infections. More pointedly, they could be helpful in the decision to improve or abandon an HIV vaccine with mediocre performance in a phase III trial.

AIDS Vaccines↗

PubMed2005

Compromised B cell responses to influenza vaccination in HIV-infected individuals.

BACKGROUND: Yearly influenza vaccination, although recommended for human immunodeficiency virus (HIV)-infected individuals, has not received thorough evaluation in the era of antiretroviral therapy. We assessed the impact of HIV disease on B cell responses to influenza vaccination. METHODS: Sixty-four HIV-infected and 17 HIV-negative individuals received the 2003-2004 trivalent inactivated influenza vaccine. Frequencies of influenza-specific antibody-secreting cells (ASCs) were measured by enzyme-linked immunospot (ELISPOT) assay, and antibody responses were measured by hemagglutination-inhibition (HI) assay. Memory responses to influenza were measured by ELISPOT assay after polyclonal activation of B cells in vitro. RESULTS: Prevaccination HI titers were significantly higher in HIV-negative than in HIV-infected individuals. Peak HI titers and influenza-specific ASC frequencies were directly correlated with CD4+ T cell counts in HIV-infected individuals. Influenza-specific memory B cell responses were significantly lower in HIV-infected than in HIV-negative individuals and were directly correlated with CD4+ T cell counts. CONCLUSIONS: HIV infection is associated with a weak antibody response to influenza vaccination that is compounded by a poor memory B cell response. CD4+ T cell count is a critical determinant of responsiveness to influenza vaccination, and the contribution of plasma HIV RNA level is suggestive and warrants further investigation.

B-Lymphocytes↗

PubMed2005

Correlation between immunologic responses to a recombinant glycoprotein 120 vaccine and incidence of HIV-1 infection in a phase 3 HIV-1 preventive vaccine trial.

BACKGROUND: An objective of the first efficacy trial of a candidate vaccine containing recombinant human immunodeficiency virus (HIV) type 1 envelope glycoprotein 120 (rgp120) antigens was to assess correlations between antibody responses to rgp120 and the incidence of HIV-1 infection. METHODS: Within the randomized trial (for vaccinees, n=3598; for placebo recipients, n=1805), binding and neutralizing antibody responses to rgp120 were quantitated. A case-cohort design was used to study correlations between antibody levels and HIV-1 incidence. RESULTS: Peak antibody levels were significantly inversely correlated with HIV-1 incidence. The relative risk (RR) of infection was 0.63 (95% confidence interval, 0.45-0.89) per log(10) higher neutralization titer against HIV-1(MN), and the RRs of infection for second-, third-, and fourth-quartile responses of antibody blocking of gp120 binding to soluble CD4 versus first-quartile responses (the lowest responses) were 0.35, 0.28, and 0.22, respectively. CONCLUSIONS: Despite inducing a complex, robust immune response, the vaccine was unable to reduce the incidence of HIV-1. Two interpretations of the correlative results are that the levels of antibodies (i) caused both an increased (low responders) and decreased (high responders) risk of HIV-1 acquisition or (ii) represented a correlate of susceptibility to HIV-1 but had no causal effect on susceptibility. Although the data cannot definitively discriminate between these 2 explanations, (ii) appears to be more likely.

AIDS Vaccines↗

PubMed2004

IL-2-induced CD4+ T-cell expansion in HIV-infected patients is associated with long-term decreases in T-cell proliferation.

Administration of interleukin 2 (IL-2) leads to selective and sustained CD4+ T-cell expansions in patients infected with HIV. It has been hypothesized that persistent CD4+ T-cell proliferation is the primary mechanism maintaining these expansions. T-cell proliferation was studied by ex vivo bromodeoxyuridine (BrdU) incorporation and intracellular Ki67 staining in HIV-infected patients treated with antiretroviral therapy (ART) with or without IL-2. In contrast to the tested hypothesis, HIV-infected patients treated with IL-2 had lower CD4+ T-cell proliferation compared to patients treated with ART alone. Independently of viral load changes, administration of IL-2 led to a decrease in basal CD4+ T-cell proliferation. Total numbers of CD4+ T cells with naive and recall, but not effector, memory phenotype were increased. The degree of CD4+ T-cell expansion correlated with the decreases in proliferation and a strong association was seen between these decreases and the expansion of the CD4+/CD25+ subset. Intermittent IL-2 in HIV-infected patients leads to expansions of CD4+/CD25+ T cells with naive and recall memory phenotypes that strongly correlate with decreases in proliferation. These data suggest that decreased T-cell proliferation is central in the CD4+ T-cell expansions induced by IL-2.

Anti-HIV Agents↗

PubMed2004

Persisting posttransplantation cytomegalovirus antigenemia correlates with poor lymphocyte proliferation to cytomegalovirus antigen and predicts for increased late relapse and treatment failure.

Numerous clinical studies link cytomegalovirus (CMV) infection with incomplete posttransplantation T-cell recovery. We hypothesized that the inability of transplant recipients to handle CMV reactivation might correlate with a defective graft-versus-leukemia response and increased posttransplantation morbidity. Between May 1995 and August 2001, 82 patients who were CMV seropositive and survived the first 100 days after transplantation were identified for a day 100 landmark analysis of the effect of CMV reactivation patterns on eventual transplantation outcome. All patients underwent a myeloablative HLA-identical sibling donor T cell-depleted stem cell transplantation with scheduled donor T-cell add-back on day 45. Median follow-up was 1032 days. Forty-two patients who had either no reactivation or only 1 positive test with quick clearance were designated as a CMV immune competent group. Forty patients designated as CMV immune deficient (ID) had at least 2 positive tests. Apart from younger age (33 versus 38 years; P =.05) in the ID group, the 2 groups were balanced for clinical characteristics. In multivariate analysis, ID patients had a significantly higher incidence of leukemia relapse (58% versus 21%; P =.03) and worse disease-free survival (31% versus 66%; P =.04). There was no significant difference in week 1 to 14 posttransplantation lymphocyte counts between the 2 groups. In 67 patients tested 3 to 6 months after transplantation, a proliferative response to CMV antigen (stimulation index > or =2) occurred in 27 of 36 immune competent patients compared with 15 of 31 ID patients (P =.006). These results show that recurrent CMV reactivation in the first 100 days after transplantation predicts for reduced disease-free survival and increased leukemic relapse beyond 100 days and correlates with inferior proliferative responses to CMV. The higher relapse rate may reflect poor immune reconstitution in ID patients or an adverse effect of prolonged antiviral treatment.

Adolescent↗

PubMed2004

Dynamics of intermittent viremia during highly active antiretroviral therapy in patients who initiate therapy during chronic versus acute and early human immunodeficiency virus type 1 infection.

The meaning of viral blips in human immunodeficiency virus type 1 (HIV-1)-infected patients treated with seemingly effective highly active antiretroviral therapy (HAART) is still controversial and under investigation. Blips might represent low-level ongoing viral replication in the presence of drug or simply release of virions from the latent reservoir. Patients treated early during HIV-1 infection are more likely to have a lower total body viral burden, a homogenous viral population, and preserved HIV-1-specific immune responses. Consequently, viral blips may be less frequent in them than in patients treated during chronic infection. To test this hypothesis, we compared the occurrence of viral blips in 76 acutely infected patients (primary HIV infection [PHI] group) who started therapy within 6 months of the onset of symptoms with that in 47 patients who started HAART therapy during chronic infection (chronic HIV infection [CHI] group). Viral blip frequency was approximately twofold higher in CHI patients (0.122 +/- 0.12/viral load [VL] sample, mean +/- standard deviation) than in PHI patients (0.066 +/- 0.09/VL sample). However, in both groups, viral blip frequency did not increase with longer periods of observation. Also, no difference in viral blip frequency was observed between treatment subgroups, and the occurrence of a blip was not associated with a recent change in CD4(+) T-cell count. Finally, in PHI patients the VL set point was a significant predictor of blip frequency during treatment.

Anti-HIV Agents↗

PubMed2003

A statistical method for adjusting covariates in linkage analysis with sib pairs.

BACKGROUND: We propose a statistical method that includes the use of longitudinal regression models and estimation procedures for adjusting for covariate effects in applying the Haseman-Elston (HE) method for linkage analysis. Our methodology, which uses the covariate adjusted trait, contains three steps: a) modelling the covariate-adjusted population means of quantitative traits through regression; b) estimating the value of covariate-adjusted quantitative traits; and c) evaluating the linkage between the adjusted trait values and the markers based on alleles shared identically by descent. RESULTS: We applied our adjusted HE method and the standard HE method in S.A.G.E. to the sib-pair subset of the Framingham Heart Study distributed by Genetic Analysis Workshop 13 with systolic blood pressure as the quantitative trait. Both methods gave similar patterns for the LOD scores, and exhibited highest multipoint LOD scores near location 70 cM of chromosome 12. CONCLUSION: The adjusted HE method has two major advantages over the standard HE method used in S.A.G.E.: a) it has the capability to handle longitudinal data; b) it provides a more natural approach for adjusting the repeatedly measured covariates from each subject.

Age Factors↗

PubMed2003

The effect of diabetes on outcomes of patients with advanced heart failure in the BEST trial.

OBJECTIVES: This was a retrospective analysis to determine the effect of diabetes on outcome in patients with advanced heart failure (HF), and to determine the effect of beta-blockade in patients with HF with and without diabetes mellitus. BACKGROUND: In chronic HF the impact on clinical outcomes and therapeutic response of the prevalent comorbid condition diabetes mellitus has not been extensively investigated. METHODS: We assessed the impact of diabetes on prognosis and effectiveness of beta-blocker therapy with bucindolol in patients with HF enrolled in the Beta-Blocker Evaluation of Survival Trial (BEST). We conducted a retrospective analysis to examine the prognosis of patients with advanced HF with and without diabetes, and the effect of beta-blocker therapy on mortality and HF progression or myocardial infarction (MI). The database was the 2,708 patients with advanced HF (36% with diabetes and 64% without diabetes) who were randomized to the beta-blocker bucindolol or placebo in BEST and followed for mortality, hospitalization, and MI for an average of two years. RESULTS: Patients with diabetes had more severe chronic HF and more coronary risk factors than patients without diabetes. Diabetes was independently associated with increased mortality in patients with ischemic cardiomyopathy (adjusted hazard ratio 1.33, 95% confidence interval 1.12 to 1.58, p = 0.001), but not in those with a nonischemic etiology (adjusted hazard ratio 0.98, 95% confidence interval 0.74 to 1.30, p = 0.89). Compared with patients without diabetes, in diabetic patients beta-blocker therapy was at least as effective in reducing death or HF hospitalizations, total hospitalizations, HF hospitalizations, and MI. Ventricular function and physiologic responses to beta-blockade were similar in patients with and without diabetes. CONCLUSIONS: Diabetes worsens prognosis in patients with advanced HF, but this worsening appears to be limited to patients with ischemic cardiomyopathy. In advanced HF beta-blockade is effective in reducing major clinical end points in patients with and without diabetes.

Adrenergic beta-Antagonists↗

PubMed2003

Antithymocyte globulin and cyclosporine for severe aplastic anemia: association between hematologic response and long-term outcome.

CONTEXT: In most patients, aplastic anemia results from T-cell-mediated immune destruction of bone marrow. Aplastic anemia can be effectively treated by stem cell transplantation or immunosuppression. OBJECTIVE: To assess long-term outcomes after immunosuppressive therapy. DESIGN, SETTING, AND PATIENTS: Cohort of 122 patients (31 were < or =18 years and 91 were >18 years) with severe aplastic anemia, as determined by bone marrow cellularity and blood cell count criteria, were enrolled in a single-arm interventional research protocol from 1991 to 1998 at a federal government research hospital. INTERVENTIONS: A dose of 40 mg/kg per day of antithymocyte globulin administered for 4 days, 10 to 12 mg/kg per day of cyclosporine for 6 months (adjusted for blood levels), and a short course of corticosteroids (1 mg/d of methylprednisolone for about 2 weeks). MAIN OUTCOME MEASURES: Survival, improvement of pancytopenia and transfusion-independence, relapse, and evolution to other hematologic diseases. RESULTS: Response rates were 60% at 3 months after initiation of treatment, 61% at 6 months, and 58% at 1 year. The blood cell counts of patients who responded no longer satisfied severity criteria and they were transfusion-independent. Overall actuarial survival at 7 years was 55%. Survival was associated with early satisfaction of response criteria (86% vs 40% at 5 years; P<.001) and by blood counts at 3 months (reticulocyte count or platelet count of >50 x 10(3)/ microL predicted survival at 5 years of 90% [64/71] vs 42% [12/34] for patients with less robust recovery [P<.001 by log-rank test]). There were no deaths among responders more than 3 years after treatment. Relapse was common, but severe pancytopenia usually did not recur. Relapse did not influence survival. Thirteen patients showed evolution to other hematologic diseases, including monosomy 7. CONCLUSIONS: Approximately half of patients with severe aplastic anemia treated with antithymocyte globulin and cyclosporine have durable recovery and excellent long-term survival. These outcomes were related to the quality of hematologic recovery.

Adolescent↗

PubMed2003

T-cell large granular lymphocyte leukemia is characterized by massive TCRBV-restricted clonal CD8 expansion and a generalized overexpression of the effector cell marker CD57.

INTRODUCTION: Large granular lymphocyte leukemia (LGL) is a clonal lymphoproliferative disease of CD8+ T cells expressing the CD57 activation marker. It is, however, unknown whether the CD57+ population represents the LGL clone or not. We previously demonstrated that the clone can be found in both CD8+CD57+ and CD8+CD57- cells, indicating that the LGL clone also resides in the CD57- fraction. MATERIALS AND METHODS: Here, we quantified the extent of the clonal CD8 expansion in LGL using T-cell receptor Vbeta (TCRBV)-specific monoclonal antibodies, and determined whether the CD4 population also contained skews. Furthermore, dominant TCRBV populations were assessed for clonal status using T-cell receptor-gamma (TCRG) PCR on genomic DNA. RESULTS: We show that the dominant TCRBV in LGL contains CD57+ and CD57- cells. Molecular analysis of CD8+CD57+ and CD8+CD57- subfractions of the dominant TCRBV by TCRG PCR demonstrates that indeed both fractions are clonal, and that the clone is absent from the dominant TCRBV-negative population. Furthermore, we show that CD57 overexpression is not restricted to the LGL clone, but a general phenomenon in CD8 cells of LGL patients. CONCLUSION: We therefore conclude that the primary characteristic of LGL is a clonal expansion of CD8 cells, with a concomitant upregulation of CD57 on this clone and uninvolved cells.

Adult↗

PubMed2003

G-CSF-induced spleen size changes in peripheral blood progenitor cell donors.

BACKGROUND: PBPC donors given G-CSF experience splenic enlargement and, rarely, spontaneous rupture of the spleen. This study evaluated the incidence and time course of splenic enlargement in PBPC concentrate donors and assessed factors affecting size changes. STUDY DESIGN AND METHODS: Twenty healthy adults were given G-CSF (10 microg/kg/day) for 5 days and a PBPC concentrate was collected by apheresis. Ultrasound was used to assess craniocaudal spleen length before giving G-CSF, on the day of apheresis and 3 or 4 days after apheresis. The effects of donor age, gender, race, and changes in blood chemistries, blood counts, and CD34+ cell counts on spleen length change were assessed. RESULTS: Spleen length increased in 19 of 20 donors. Mean length changed from 10.9 +/- 2.0 cm before G-CSF to 12.3 +/- 2.1 cm on the day of apheresis (p < 0.001). The mean increase in length was 1.5 +/- 0.9 cm or 13.8 +/- 9.1 percent. Spleen length increased 20 percent or more in six subjects. The spleen length fell to 11.3 +/- 1.8 cm (p < 0.001) 3 or 4 days after apheresis, but it remained greater than baseline levels (p = 0.03). Spleen length change was not affected by donor gender, race, or age. There was no relationship between changes in spleen length and 1) baseline and apheresis-day blood counts and chemistries, or 2) changes in blood counts and chemistries. CONCLUSIONS: Spleen size increases in almost all PBPC donors. Enlargement is transient but may be marked in some donors and may place them at risk for splenic rupture.

Adult↗

PubMed2003

A comparative analysis of the results from 4 trials of beta-blocker therapy for heart failure: BEST, CIBIS-II, MERIT-HF, and COPERNICUS.

BACKGROUND: Recent large randomized, controlled trials (BEST [Beta-blocker Evaluation of Survival Trial], CIBIS-II [Cardiac Insufficiency Bisoprolol Trial II], COPERNICUS [Carvedilol Prospective Randomized Cumulative Survival Study], and MERIT-HF [Metoprolol Randomized Intervention Trial in Congestive Heart Failure]) have addressed the usefulness of beta-blockade in the treatment of advanced heart failure. CIBIS-II, COPERNICUS, and MERIT-HF have shown that beta-blocker treatment with bisoprolol, carvedilol, and metoprolol XL, respectively, reduce mortality in advanced heart failure patients, whereas BEST found a statistically nonsignificant trend toward reduced mortality with bucindolol. We conducted a post hoc analysis to determine whether the response to beta-blockade in BEST could be related to differences in the clinical and demographic characteristics of the study populations. We generated a sample from BEST to resemble the patient cohorts studied in CIBIS-II and MERIT-HF to find out whether the response to beta-blocker therapy was similar to that reported in the other trials. These findings are further compared with COPERNICUS, which entered patients with more severe heart failure. METHODS: To achieve conformity with the entry criteria for CIBIS-II and MERIT-HF, the BEST study population was adjusted to exclude patients with systolic blood pressure <100 mm Hg, heart rate <60 bpm, and age >80 years (exclusion criteria employed in those trials). The BEST comparison subgroup (BCG) was further modified to more closely reflect the racial demographics reported for patients enrolled in CIBIS-II and MERIT-HF. The association of beta-blocker therapy with overall survival and survival free of cardiac death, sudden cardiac death, and progressive pump failure in the BCG was assessed. RESULTS: In the BCG subgroup, bucindolol treatment was associated with significantly lower risk of death from all causes (hazard ratio (HR)=0.77 [95% CI=0.65, 0.92]), cardiovascular death (HR=0.71 [0.58, 0.86]), sudden death (HR=0.77 [0.59, 0.999]), and pump failure death (HR=0.64 [0.45, 0.91]). CONCLUSIONS: Although not excluding the possibility of differences resulting from chance alone or to different properties among beta-blockers, this study suggests the possibility that different heart failure population subgroups may have different responses to beta-blocker therapy.

Adolescent↗

PubMed2003

Multiple outputation: inference for complex clustered data by averaging analyses from independent data.

This article applies a simple method for settings where one has clustered data, but statistical methods are only available for independent data. We assume the statistical method provides us with a normally distributed estimate, theta, and an estimate of its variance sigma. We randomly select a data point from each cluster and apply our statistical method to this independent data. We repeat this multiple times, and use the average of the associated theta's as our estimate. An estimate of the variance is given by the average of the sigma2's minus the sample variance of the theta's. We call this procedure multiple outputation, as all "excess" data within each cluster is thrown out multiple times. Hoffman, Sen, and Weinberg (2001, Biometrika 88, 1121-1134) introduced this approach for generalized linear models when the cluster size is related to outcome. In this article, we demonstrate the broad applicability of the approach. Applications to angular data, p-values, vector parameters, Bayesian inference, genetics data, and random cluster sizes are discussed. In addition, asymptotic normality of estimates based on all possible outputations, as well as a finite number of outputations, is proven given weak conditions. Multiple outputation provides a simple and broadly applicable method for analyzing clustered data. It is especially suited to settings where methods for clustered data are impractical, but can also be applied generally as a quick and simple tool.

Acute Disease↗

PubMed2002

Intracellular interferon-gamma in circulating and marrow T cells detected by flow cytometry and the response to immunosuppressive therapy in patients with aplastic anemia.

Immunosuppressive therapy leads to meaningful hematologic improvement in most patients with aplastic anemia (AA). Failure to respond and a later relapse could be due to deficient numbers of hematopoietic stem cells, inadequate treatment of the immune process, or a nonimmunologic etiology. Interferon-gamma (IFN-gamma) has been implicated in the pathophysiology of hematopoietic failure in AA. On the basis of previous findings showing overexpression of IFN-gamma in bone marrow (BM) and peripheral blood (PB) in this disease, we hypothesized that quantitation of IFN-gamma might be applied to predict and monitor responses to immunosuppressive therapy. We measured expression of IFN-gamma in lymphocytes obtained from 123 AA patients, using intracellular 2-color fluorescent staining and flow cytometry. Of 70 patients with severe AA, 36 (51%) demonstrated increased IFN-gamma in circulating T cells. IFN-gamma was detected in only 4 of 53 patients who had recovered from AA. IFN-gamma was not found in PB lymphocytes of patients with other hematologic diseases and heavy transfusion burdens or in healthy volunteers. Among 62 AA patients who were assessed before first treatment with immunosuppressive drugs, 27 of 28 (96%) with circulating IFN-gamma-containing T cells subsequently responded to therapy; in contrast, only 11 of 34 (32%) patients whose PB lacked IFN-gamma lymphocytes improved to transfusion independence. IFN-gamma-containing lymphocytes declined following treatment in all cases. Of 17 patients assessed during relapse, IFN-gamma was present in T cells prior to the blood count decline in 13, and 12 responded to reinstitution of immunosuppressive drugs. Of 30 BMs tested prior to first treatment, 20, all in responding patients, were positive for IFN-gamma, whereas the negative tests were obtained in 10 nonresponding patients. IFN-gamma is increased in the PB lymphocytes of many patients with AA, and these cells decline with therapy. The presence of intracellular IFN-gamma may predict response to immunosuppressive treatment and also the onset of relapse.

Anemia, Aplastic↗

PubMed2002

Molecular and flow cytometric characterization of the CD4 and CD8 T-cell repertoire in patients with myelodysplastic syndrome.

We studied 18 patients with myelodysplastic syndrome (MDS), measuring clonality and T-cell receptor Vbeta (TCRBV) expression of CD4 and CD8 T cells by polymerase chain reaction and by flow cytometric analysis of TCRBV families. The CD4 and CD8 T-cell repertoire in most MDS patients is characterized by an abnormal TCRBV-restricted expansion of T cells in CD4 and CD8 cells, and increased expression of the CD8 effector marker CD57 of multiple TCRBV in CD8 cells. Clonality analysis of CD4 and CD8 cells showed that seven of 10 patients analysed had a major clone in the CD8 cells but not in CD4 cells. Furthermore, in one patient we found that both the CD57- and CD57+ fraction contained the clone (which was absent from the TCRBV-negative fraction). These data suggest that, in MDS, multiple T-cell expansions can be found in both helper and cytotoxic T cells, and that, in the CD8 cells, T cells functionally differentiate in vivo from memory to effector T cells. Together, these data support the hypothesis of the involvement of T cells in the pathogenesis of MDS.

Adult↗