Prevalence and predictors of airflow obstruction in an HIV tertiary care clinic in Montreal, Canada: a cross-sectional study.

OBJECTIVES: The reported prevalence of chronic obstructive pulmonary disease (COPD) in people living with HIV (PLWHIV) varies widely. Our objective was to estimate the prevalence of airflow obstruction and COPD in unselected PLWHIV and identify characteristics that increase the risk of nonreversible airflow obstruction in order to guide case finding strategies for COPD. METHODS: All adults attending the Chronic Viral Illness Service were invited to participate in the study, regardless of smoking status or history of known COPD/asthma. Individuals underwent spirometric testing both before and after use of a salbutamol bronchodilator. Airflow obstruction was defined as forced expiratory volume in 1 s (FEV1 )/forced vital capacity (FVC) < 0.7 post-bronchodilation, whereas COPD was defined as FEV1 /FVC < 0.7 post-bronchodilation and Medical Research Council (MRC) score > 2. Multivariate logistic regression was used to evaluate risk factors associated with airflow obstruction, reported as adjusted odds ratios (aORs). RESULTS: Five hundred and three participants successfully completed spirometry testing. The median (Q1; Q3) age was 52 (44; 58) years. The median (Q1; Q3) CD4 count was 598 (438; 784) cells/µL and the median (Q1; Q3) nadir CD4 count was 224 (121; 351) cells/µL. There were 119 (24%) current smokers and 145 (29%) former smokers. Among those screened, 54 (11%) had airflow obstruction whereas three (1%) of the participants had COPD. Factors that were associated with airflow obstruction included a history of smoking [aOR 2.2; 95% confidence interval (CI) 1.1; 4.7], older age (aOR 1.6; 95% CI 1.2; 2.2), and lower CD4 count (aOR 0.8; 95% CI 0.7; 1.0). CONCLUSIONS: Airflow obstruction was relatively uncommon. Our findings suggest that PLWHIV who are ≥50 years old, smokers and those with nadir CD4 counts ≤ 200 cells/µL could be targeted to undergo spirometry to diagnose chronic airflow obstruction.

Quality of initial HIV care in Canada: extension of a composite programmatic assessment tool for HIV therapy.

OBJECTIVES: To document the quality of initial HIV care in Canada using the Programmatic Compliance Score (PCS), to explore the association of the PCS with mortality, and to identify factors associated with higher quality of care. METHODS: We analysed data from the Canadian Observational Cohort Collaboration (CANOC), a multisite Canadian cohort of HIV-positive adults initiating combination antiretroviral therapy (ART) from 2000 to 2011. PCS indicators of noncompliance with HIV treatment guidelines include: fewer than three CD4 count tests in the first year of ART; fewer than three viral load tests in the first year of ART; no drug resistance testing before initiation; baseline CD4 count < 200 cells/mm3 ; starting a nonrecommended ART regimen; and not achieving viral suppression within 6 months of initiation. Indicators are summed for a score from 0 to 6; higher scores indicate poorer care. Cox regression was used to assess the association between PCS and mortality and ordinal logistic regression was used to explore factors associated with higher quality of care. RESULTS: Of the 7460 participants (18% female), the median score was 1.0 (Q1-Q3 1.0-2.0); 21% scored 0 and 8% scored ≥ 4. In multivariable analysis, compared with a score of 0, poorer PCS was associated with mortality for scores > 1 [score = 2: adjusted hazard ratio (AHR) 1.64; 95% confidence interval (CI) 1.13-2.36; score = 3: AHR 2.02; 95% CI 1.38-2.97; score ≥ 4: AHR 2.14; 95% CI 1.43-3.21], after adjustments for age, sex, province, ART start year, hepatitis C virus (HCV) coinfection, and baseline viral load. Women, individuals with HCV coinfection, younger people, and individuals starting ART earlier (2000-2003) had poorer scores. CONCLUSIONS: Our findings further validate the PCS as a predictor of all-cause mortality. Disparities identified suggest that further efforts are needed to ensure that care is equitably accessible.

A tale of two countries: all-cause mortality among people living with HIV and receiving combination antiretroviral therapy in the UK and Canada.

OBJECTIVES: We sought to compare all-cause mortality of people living with HIV and accessing care in Canada and the UK. METHODS: Individuals from the Canadian Observational Cohort (CANOC) collaboration and UK Collaborative HIV Cohort (UK CHIC) study who were aged ≥ 18 years, had initiated antiretroviral therapy (ART) for the first time between 2000 and 2012 and who had acquired HIV through sexual transmission were included in the analysis. Cox regression was used to investigate the difference in mortality risk between the two cohort collaborations, accounting for loss to follow-up as a competing risk. RESULTS: A total of 19 960 participants were included in the analysis (CANOC, 4137; UK CHIC, 15 823). CANOC participants were more likely to be older [median age 39 years (interquartile range (IQR): 33, 46 years) vs. 36 years (IQR: 31, 43 years) for UK CHIC participants], to be male (86 vs. 73%, respectively), and to report men who have sex with men (MSM) sexual transmission risk (72 vs. 56%, respectively) (all P < 0.001). Overall, 762 deaths occurred during 98 798 person-years (PY) of follow-up, giving a crude mortality rate of 7.7 per 1000 PY [95% confidence interval (CI): 7.1, 8.3 per 1000 PY]. The crude mortality rates were 8.6 (95% CI: 7.4, 10.0) and 7.5 (95% CI: 6.9, 8.1) per 1000 PY among CANOC and UK CHIC study participants, respectively. No statistically significant difference in mortality risk was observed between the cohort collaborations in Cox regression accounting for loss to follow-up as a competing risk (adjusted hazard ratio 0.86; 95% CI: 0.72-1.03). CONCLUSIONS: Despite differences in national HIV care provision and treatment guidelines, mortality risk did not differ between CANOC and UK CHIC study participants who acquired HIV through sexual transmission.

Predictors of unstructured antiretroviral treatment interruption and resumption among HIV-positive individuals in Canada.

OBJECTIVES: Sustained optimal use of combination antiretroviral therapy (cART) has been shown to decrease morbidity, mortality and HIV transmission. However, incomplete adherence and treatment interruption (TI) remain challenges to the full realization of the promise of cART. We estimated trends and predictors of treatment interruption and resumption among individuals in the Canadian Observational Cohort (CANOC) collaboration. METHODS: cART-naïve individuals ≥ 18 years of age who initiated cART between 2000 and 2011 were included in the study. We defined TIs as ≥ 90 consecutive days off cART. We used descriptive analyses to study TI trends over time and Cox regression to identify factors predicting time to first TI and time to treatment resumption after a first TI. RESULTS: A total of 7633 participants were eligible for inclusion in the study, of whom 1860 (24.5%) experienced a TI. The prevalence of TI in the first calendar year of cART decreased by half over the study period. Our analyses highlighted a higher risk of TI among women [adjusted hazard ratio (aHR) 1.59; 95% confidence interval (CI) 1.33-1.92], younger individuals (aHR 1.27; 95% CI 1.15-1.37 per decade increase), earlier treatment initiators (CD4 count ≥ 350 vs. <200 cells/µL: aHR 1.46; 95% CI 1.17-1.81), Aboriginal participants (aHR 1.67; 95% CI 1.27-2.20), injecting drug users (aHR 1.43; 95% CI 1.09-1.89) and users of zidovudine vs. tenofovir in the initial cART regimen (aHR 2.47; 95% CI 1.92-3.20). Conversely, factors predicting treatment resumption were male sex, older age, and a CD4 cell count <200 cells/µL at cART initiation. CONCLUSIONS: Despite significant improvements in cART since its advent, our results demonstrate that TIs remain relatively prevalent. Strategies to support continuous HIV treatment are needed to maximize the benefits of cART.

Characteristics and determinants of T-cell phenotype normalization in HIV-1-infected individuals receiving long-term antiretroviral therapy.

OBJECTIVES: Although combination antiretroviral therapy (cART) can restore CD4 T-cell numbers in HIV infection, alterations in T-cell regulation and homeostasis persist. We assessed the incidence and predictors of reversing these alterations with cART. METHODS: ART-naïve adults (n = 4459) followed within the Canadian Observational Cohort and exhibiting an abnormal T-cell phenotype (TCP) prior to cART initiation were studied. Abnormal TCP was defined as having (1) a low CD4 T-cell count (< 532 cells/µL), (2) lost T-cell homeostasis (CD3 < 65% or > 85%) or (3) CD4:CD8 ratio dysregulation (ratio < 1.2). To thoroughly evaluate the TCP, CD4 and CD8 T-cell percentages and absolute counts were also analysed for a median duration of 3.14 years [interquartile range (IQR) 1.48-5.47 years]. Predictors of TCP normalization were assessed using adjusted Cox proportional hazards models. RESULTS: At baseline, 96% of pateints had CD4 depletion, 32% had lost homeostasis and 99% exhibited ratio dysregulation. With treatment, a third of patients had normalized CD4 T-cell counts, but only 85 individuals (2%) had normalized their TCP. In a multivariable model adjusted for age, measurement frequency and baseline regimen, higher baseline CD4 T-cell counts and time-dependent viral suppression independently predicted TCP normalization [hazard ratio (HR) for baseline CD4 T-cell count = 1.42 (1.31-1.54) per 100 cells/µL increase; P ≤ 0.0001; HR for time-dependent suppressed viral load = 3.69 (1.58-8.61); P-value ≤ 0.01]. CONCLUSIONS: Despite effective cART, complete TCP recovery occurred in very few individuals and was associated with baseline CD4 T-cell count and viral load suppression. HIV-induced alterations of the TCP are incompletely reversed by long-term ART.

Relationship of chronic hepatitis C infection to rates of AIDS-defining illnesses in a Canadian cohort of HIV seropositive individuals receiving highly active antiretroviral therapy.

BACKGROUND: The influence of chronic hepatitis C virus (HCV) infection on the risk, timing, and type of AIDS-defining illnesses (ADIs) is not well described. To this end, rates of ADIs were evaluated in a Canadian cohort of HIV seropositive individuals receiving highly active antiretroviral therapy (HAART). METHODS: ADIs were classified into 6 Centers for Disease Control and Prevention (CDC)-defined etiological subgroups: non-Hodgkin lymphoma, viral infection, bacterial infection, HIV-related disease, protozoal infection, and mycotic infection. Generalized estimating equation (GEE) Poisson regression models were used to estimate the effect of HCV on rates of ADIs after adjusting for covariates. RESULTS: Among 2,706 HAART recipients, 768 (28%) were HCV coinfected. Rates of all ADIs combined and of bacterial infection, HIV-related disease, and mycotic infection were increased in HCV-coinfected persons and among those with CD4 counts <200 cells/mm3 HCV was associated with an increased risk of ADIs (rate ratio [RR], 1.38; 95% CI, 1.01-1.88) and a 2-fold increased risk of mycotic infections (RR, 2.21; 95% CI, 1.35-3.62) in univariate analyses and after adjusting for age, baseline viral load, baseline CD4 count, and region of Canada. However, after further adjustment for HAART interruptions, HCV was no longer associated with an increased rate of ADIs overall (RR, 1.13; 95% CI, 0.80-1.59), but remained associated with an increased rate of mycotic infections (RR, 1.97, 95% CI, 1.08-3.61). CONCLUSION: Although HCV coin-fected individuals are at increased risk of developing ADIs overall, our analysis suggests that behavioral variables associated with HCV (including rates of retention on HAART), and not biological interactions with HCV itself, are primarily responsible.

Factors associated with virological suppression among HIV-positive individuals on highly active antiretroviral therapy in a multi-site Canadian cohort.

OBJECTIVE: The aim of the study was to evaluate time to virological suppression in a cohort of individuals who started highly active antiretroviral therapy (HAART), and to explore the factors associated with suppression. METHODS: Eligible participants were HIV-positive individuals from a multi-site Canadian cohort of antiretroviral-naïve patients initiating HAART on or after 1 January 2000. Viral load and CD4 measurements within 6 months prior to HAART initiation were assessed. Univariate and multivariate analyses were conducted using piecewise survival exponential models where time scale was divided into intervals (<10 months; ≥10 months). Virological suppression was defined as the time to the first of at least two consecutive viral load measurements <50 HIV-1 RNA copies/mL. RESULTS: A total of 3555 individuals were included in the study, of median age 40 years [interquartile range (IQR) 34-47 years]. Eighty per cent were male, 18% had a history of injecting drug use (IDU), and 13% presented with an AIDS-defining illness at baseline. The median time to suppression was 4.55 months (IQR 2.99-7.89 months). In multivariate analyses, older age, male sex, treatment in Ontario rather than British Columbia, non-IDU history, and having an AIDS diagnosis at baseline predicted increased likelihood of suppression. Patients with low baseline viral load were more likely to have suppression [4-5 log(10) copies/mL, hazard ratio (HR) 1.27, 95% confidence interval (CI) 1.18-1.38; <4 log(10) copies/mL, HR 1.49, 95% CI 1.32-1.68] than patients with baseline viral load ≥5 log(10) copies/mL; however, this effect ceased after 18 months of follow-up. Suppression was more likely with nonnucleoside reverse transcriptase inhibitors and ritonavir-boosted HAART. CONCLUSION: Identification of patients at risk for diminished likelihood of virological suppression will allow focusing of efforts and the utilization of resources to maximize the benefits of HAART.

B cell stimulating factor 2/interleukin 6 is a costimulant for human thymocytes and T lymphocytes.

Growth and differentiation of thymocytes and mature T lymphocytes is regulated by cellular interactions that are in part mediated by soluble factors. We identify IL-6, formerly called B cell stimulating factor (BSF-2). IFN-beta 2, or hybridoma-plasmacytoma growth factor (HPGF) as a novel T cell costimulant rIL-6 induced a six-to seven-fold increase in proliferation of human thymocytes stimulated with suboptimal doses of PHA. A similar effect with added IL-6 could be observed using peripheral blood T lymphocytes, but only if the cultures were first rigorously depleted of monocytes that release high levels of IL-6. Analysis of the mechanism of the IL-6 effect on thymocytes and T lymphocytes showed that IL-6 did not lead to an increase in IL-2-R expression. Concentrations of antibody to IL-2-R inhibiting IL-2 effects did not block the IL-6-induced proliferation, indicating that the IL-6 effect was relatively IL-2 independent. These results identify IL-6 as a novel costimulant of human thymocytes and mature T lymphocytes, and suggest that IL-6 is also an important regulatory of cellular immunity.

CD81 expressed on human thymocytes mediates integrin activation and interleukin 2-dependent proliferation.

Lymphocyte recognition of antigen by the antigen-specific T cell receptor (TCR) and coreceptor complexes rapidly alters the cell's adhesive properties facilitating high avidity cell-ligand interactions necessary for lymphocyte development and function. Here, we report the expression of CD81 (target of antiproliferative antigen [TAPA]-1) on human thymocytes and the physical association of CD81 with CD4 and CD8 T cell coreceptors. Antibody ligation of CD81 on thymocytes promotes the rapid induction of integrin-mediated cell-cell adhesion via lymphocyte function-associated molecule-1 (LFA-1). Cross-linking CD81 is also shown to be costimulatory with signaling through the TCR/CD3 complex inducing interleukin 2-dependent thymocyte proliferation. These data suggest that a CD81-mediated pathway in thymocytes is involved in the regulation of both cell adhesion and activation.

Infection of human thymocytes by Epstein-Barr virus.

The Epstein-Barr Virus (EBV) causes infectious mononucleosis, and has been strongly associated with certain human cancers. The virus is thought to exclusively bind to B lymphocytes and epithelial cells via receptors (CR2/CD21) that also interact with fragments of the third component of complement (C3). Recent evidence, however, has challenged this belief. We have used two-color immunofluorescence analysis using biotin-conjugated EBV and streptavidin-phycoerythrin along with fluorescein-conjugated anti-T cell antibodies and demonstrated that CD1-positive, CD3-dull (immature) human thymocytes express functional EBV receptors. In four replicate experiments, the binding of EBV to thymocytes ranged between 8 and 18%. This interaction is specific as evidenced by inhibition with nonconjugated virus, anti-CR2 antibodies, aggregated C3, and an antibody to the gp350 viral glycoprotein that the virus uses to bind to CR2. EBV can infect the thymocytes as evaluated by the presence of episomal EBV-DNA in thymocytes that had been incubated with the virus as short as 12 days or as long as 6 weeks. Episomal DNA analysis was performed by Southern blotting with a EBV-DNA probe that hybridizes to the first internal reiteration of the viral DNA. The presence of the EBV genome is also supported by the detection of EBV nuclear antigen 1 in infected thymocytes, assessed by Western blotting with EBV-immune sera. The EBV infection is specific as determined by blocking experiments using anti-CR2 and anti-gp350 antibodies. Finally, virus infection of thymocytes can act synergistically along with interleukin 2 and induce a lymphokine-dependent cellular proliferation. In view of previously reported cases of EBV-positive human T cell lymphomas, the possibility is raised that EBV may be involved in cancers of T lymphocytes that have not been previously appreciated.

Pharmacokinetics and safety of subcutaneous immune globulin (human), 10% caprylate/chromatography purified in patients with primary immunodeficiency disease.

Subcutaneous administration of intravenous immunoglobulin G (IgG) preparations provides an additional level of patient convenience and more options for patients with poor venous access or a history of intravenous IgG reactions. An open-label, pharmacokinetic trial (n = 32) determined the non-inferiority of the subcutaneous versus intravenous route of 10% caprylate/chromatography purified human immune globulin intravenous (IGIV-C; Gamunex®) administration by comparing the steady-state area under the concentration-versus-time curve (AUC) of total plasma IgG in patients with primary immunodeficiency disease. Patients on stable IGIV-C received two intravenous infusions (administered 3 or 4 weeks apart). Seven to 10 days after the second intravenous infusion, all patients switched to a weekly infusion of subcutaneous IGIV-C, with the dose equal to 137% of the previous weekly equivalent intravenous dose, for up to 24 weeks. Samples for pharmacokinetic analysis were collected during steady state for intravenous and subcutaneous IGIV-C treatments. The AUC(0-) τ geometric least-squares mean ratio was 0·89 (90% confidence interval, 0·86-0·92) and met the criteria for non-inferiority. The overall mean steady-state trough concentration of plasma total IgG with subcutaneous IGIV-C was 11·4 mg/ml, 18·8% higher than intravenous IGIV-C (9·6 mg/ml). Subcutaneous IGIV-C was safe and well tolerated. Subcutaneous IGIV-C infusion-site reactions were generally mild/moderate and the incidence decreased over time. No serious bacterial infections were reported. Weekly subcutaneous IGIV-C infusion using 137% of the weekly equivalent intravenous immunoglobulin dose provides an AUC comparable to intravenous administration, thus allowing patients to maintain the same IgG preparation/formulation if switching between intravenous and subcutaneous infusions.

1,25-dihydroxyvitamin D3: a novel immunoregulatory hormone.

The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], at picomolar concentrations, inhibited the growth-promoting lymphokine interleukin-2, which is produced by human T lymphocytes activated in vitro by the mitogen phytohemagglutinin. Other metabolites of vitamin D3 were less effective than 1,25(OH)2D3 in suppressing interleukin-2; their order of potency corresponded to their respective affinity for the 1,25(OH)2D3 receptor, suggesting that the effect on interleukin-2 was mediated by this specific receptor. The proliferation of mitogen-activated lymphocytes was also inhibited by 1,25(OH)2D3. This effect of the hormone became more pronounced at later stages of the culture. These findings demonstrate that 1,25(OH)2D3 is an immunoregulatory hormone.

1,25-dihydroxyvitamin D3 receptors in human leukocytes.

A 1,25-dihydroxyvitamin D3 receptor macromolecule was detected in peripheral mononuclear leukocytes from normal humans. This macromolecule was found to be present in monocytes but absent from normal resting peripheral B and T lymphocytes. However, it was present in established lines of malignant B, T, and non-B, non-T human lymphocytes, as well as in T and B lymphocytes obtained from normal humans and activated in vitro.

Inheritance of immunoglobulin M rheumatoid-factor idiotypes.

The idiotypic determinants on IgM rheumatoid factor (RF) from a single family have been analyzed. Rabbit Fab'2 antiidiotypic antibody was prepared against purified IgM-RF from a patient with rheumatoid arthritis. As measured by radioimmunoassay, the antiidiotype reacted with at least 90% of the patient's RF, but not with non-RF immunoglobulins from the same serum, nor with 10 of 11 polyclonal and monoclonal RF from unrelated individuals. Cross-reacting idiotypes were detected on RF in four of the patients' first degree relatives, spanning three generations, without apparent relation of HLA type or clinical rheumatoid arthritis. These results suggest that IgM-RF associated idiotypes were inherited in this family.

Basis for defective responses of rheumatoid arthritis synovial fluid lymphocytes to anti-CD3 (T3) antibodies.

Synovial fluid mononuclear cells (SFMC) from patients with active rheumatoid arthritis characteristically respond poorly to mitogens. In this study, mitogenic antibodies reactive with the CD3(T3) antigen on human T lymphocytes were used to analyze the basis for the deficiency. OKT3-induced proliferation and release of interleukin 1 (IL-1) and interleukin 2 (IL-2) from SFMC were depressed in all patients. Purified IL-1 or recombinant IL-2 restored proliferative responses in SFMC and increased IL-2 receptor density. Exogenous IL-1 also enhanced IL-2 release. Fractionation of SFMC supernatants on phosphocellulose columns revealed the presence of IL-1 and a potent IL-1 inhibitor. The monocyte-derived IL-1 inhibitor blocked IL-1-dependent responses of normal peripheral blood lymphocytes to OKT3, but had no effect on IL-2-dependent events. These results suggest that IL-1 inhibitor(s) in SFMC impair(s) OKT3-induced mitogenesis by interfering with the effects of IL-1 on T lymphocytes. The net result is deficient IL-2 secretion, IL-2 receptor expression, and impaired cellular proliferation. This novel inhibitory circuit provides a rational explanation for the diminished function of synovial fluid T lymphocytes in rheumatoid arthritis patients.

Low urine pH is associated with reduced indinavir crystalluria in indinavir-treated HIV-infected individuals.

Indinavir is a potent HIV-1 protease inhibitor included in current antiretroviral therapeutic regimens. It is associated with renal and urological complications ascribed to indinavir crystalluria. We have previously reported that indinavir crystalluria is frequently observed soon after initiation of therapy. In a cohort of 54 asymptomatic indinavir-naive HIV-1-infected individuals during their first year of treatment with indinavir, approximately 25% of urinalyses (U/A) contained indinavir crystals. Because the determinants of the crystalluria are unknown, we examined the relationship between urine specific gravity (SG) and pH, singly and in combination, and indinavir crystalluria in these subjects. A total of 579 U/A were obtained from the study subjects at their scheduled monthly outpatient medical assessments. The frequency of indinavir crystalluria was lower in U/A with lower pH, irrespective of the SG. Conversely, U/A with high pH (> or = 6.0) had a higher frequency of indinavir crystalluria, which was further influenced by the urine SG. As a result, nearly half of the U/A (46.7%) with high pH (> or = 6.0) and intermediate-high SG (> or = 1.015) contained indinavir crystals. In conclusion, the frequency of indinavir crystalluria in asymptomatic HIV-1 infected individuals during their first year of treatment with indinavir was markedly influenced by the urine pH and SG. Our findings suggest that low urine pH may have a protective effect against indinavir crystalluria across the entire range of urine SG.

Selection of molecular descriptors with artificial intelligence for the understanding of HIV-1 protease peptidomimetic inhibitors-activity.

Quantitative Structure Activity Relationship (QSAR) techniques are used routinely by computational chemists in drug discovery and development to analyze datasets of compounds. Quantitative numerical methods like Partial Least Squares (PLS) and Artificial Neural Networks (ANN) have been used on QSAR to establish correlations between molecular properties and bioactivity. However, ANN may be advantageous over PLS because it considers the interrelations of the modeled variables. This study focused on the HIV-1 Protease (HIV-1 Pr) inhibitors belonging to the peptidomimetic class of compounds. The main objective was to select molecular descriptors with the best predictive value for antiviral potency (Ki). PLS and ANN were used to predict Ki activity of HIV-1 Pr inhibitors and the results were compared. To address the issue of dimensionality reduction, Genetic Algorithms (GA) were used for variable selection and their performance was compared against that of ANN. Finally, the structure of the optimum ANN achieving the highest Pearson's-R coefficient was determined. On the basis of Pearson's-R, PLS and ANN were compared to determine which exhibits maximum performance. Training and validation of models was performed on 15 random split sets of the master dataset consisted of 231 compounds. For each compound 192 molecular descriptors were considered. The molecular structure and constant of inhibition (Ki) were selected from the NIAID database. Study findings suggested that non-covalent interactions such as hydrophobicity, shape and hydrogen bonding describe well the antiviral activity of the HIV-1 Pr compounds. The significance of lipophilicity and relationship to HIV-1 associated hyperlipidemia and lipodystrophy syndrome warrant further investigation.

A phase I study of letrazuril in AIDS-related cryptosporidiosis.

OBJECTIVE: The intestinal parasite Cryptosporidium is a common cause of chronic diarrhoea in AIDS patients and is responsible for significant morbidity and mortality. No effective treatment is currently available for this condition. Here we aim to determine the safety, tolerance, and clinical effect of letrazuril in the treatment of AIDS-related Cryptosporidiosis. DESIGN: A prospective, open-label study of letrazuril was performed. SETTING: The study was conducted at the Immune Deficiency Treatment Centre (IDTC) of Montreal General Hospital, a tertiary-care centre with inpatient and outpatient facilities. PARTICIPANTS: All HIV-positive patients presenting to the IDTC between November 1991 and January 1993 who had symptomatic intestinal Cryptosporidiosis were enrolled in this protocol. Sixteen participants entered the study and 15 were available for evaluation, having completed at least 2 weeks on the study medication. INTERVENTIONS: Patients received letrazuril daily in escalating doses of 50 to 100 mg orally for 6 weeks. Clinical and laboratory evaluations were performed weekly during the treatment phase, with a follow-up evaluation 4 weeks after the end of this phase, for a total study period of 10 weeks. MAIN OUTCOME MEASURES: Response to letrazuril was assessed by eradication of Cryptosporidial oocysts from the stool and symptomatic improvement in diarrhoea and abdominal pain. Haematological, biochemical, and electrocardiographic parameters were also studied to evaluate potential toxicities of the treatment. RESULTS: Fourteen evaluable patients had baseline CD4 lymphocyte counts ranging from 3 to 99 x 10(6)/l cells (mean, 30 x 10(6)/l cells). (The fifteenth evaluable patient had a CD4 count 235 x 10(6)/l.) Of these 14 patients, five showed a major response (symptomatic improvement and eradication of Cryptosporidial oocysts from the stool), two had a minor response (symptomatic improvement with persistence of oocysts in stool), and seven had no response to therapy with letrazuril. Seven patients developed a transient drug-related rash. CONCLUSION: Fifty per cent of the AIDS patients in this study experienced an improvement in their Cryptosporidial disease while receiving letrazuril. No serious dose-related toxicities were observed. Larger Phase II trials are needed to evaluate the safety and efficacy of letrazuril in AIDS-associated intestinal Cryptosporidiosis.

HIV-specific cytotoxic T-lymphocyte activity in immunologically normal HIV-infected persons.

BACKGROUND: CD8+ T-cell counts usually increase soon after infection with HIV, whereas CD4+ cell counts decrease. The result of these changes in T-cell subpopulation subsets in most HIV-infected subjects is inversion of the CD4 : CD8 ratio from greater than 1.0 typical of uninfected persons to less than 1.0 after infection. SUBJECTS: Six HIV-infected individuals were identified in whom the CD4 : CD8 ratio remained normal throughout follow-up (4.0-11.25 years). They all maintained levels of CD4+ cells above 500 x 10(6)/l and had never received antiretroviral therapy. Because HIV-specific cytotoxic T lymphocytes (CTL) have been implicated in control of HIV during the asymptomatic phase of disease, we screened these individuals for the presence of HIV-specific CTL activity. METHODS: CTL activity was assessed in freshly isolated peripheral blood mononuclear cells (PBMC) and in phytohaemagglutinin-stimulated interleukin-2 expanded cell lines established from PBMC. Cytotoxicity to HIV-1 env, gag, pol and nef gene products was surveyed in a 4 h 51Cr-release assay using autologous Epstein-Barr virus (EBV) transformed B cells infected with vaccinia constructs expressing each of these HIV genes. The immunodominant CTL epitope and MHC class I antigen restriction specificity of HIV-specific CTL was mapped when present. Plasma viral load was assessed by branched DNA assay. Attempts were made to isolate virus from these individuals by the PBMC coculture assay. RESULTS: None of the six immunologically normal HIV-infected (INHI) subjects exhibited direct HIV-specific CTL activity in their freshly isolated PBMC compared with 16 (47%) out of 34 HIV disease progressors (P = 0.03, chi2 test) and one out of 10 seronegative subjects. Three of the six INHI subjects had detectable memory HIV-specific precursor CTL (pCTL) activity in in vitro-activated T-cell lines compared with 25 (73.5%) out of 34 HIV-1 disease progressors and in none out of 10 seronegative individuals. All three INHI subjects had Gag-specific pCTL, and none had reverse transcriptase-specific pCTL. Plasma HIV viraemia in all six INHI subjects was below the level of detection by branched DNA assay (< 500 copies/ml). Virus could not be isolated from four of these individuals despite multiple attempts to do so by PBMC coculture assays. CONCLUSION: Direct HIV-specific CTL activity mediated by activated circulating PBMC was undetectable in six INHI individuals under conditions where it is frequently observed in HIV disease progressors. Despite the absence of cells activated for killing HIV-infected targets in the circulation of these individuals, they appeared able to control their HIV infection by maintaining normal levels of CD4 and CD8 cells and low viral load.