Seropositivity for HIV and the development of AIDS or AIDS related condition: three year follow up of the San Francisco General Hospital cohort

Survival of elderly patients with transfusion-related acquired immunodeficiency syndrome

OBJECTIVE

To determine the influences of age and risk group on the survival of AIDS patients. We concentrated on transfusion because it is the commonest risk factor for AIDS in patients over 70 years of age.

DESIGN

Survival curve regression analysis.

PARTICIPANTS

Patients aged 13 years and over with AIDS acquired through transfusion, and patients 65 years or older with AIDS as a result of intravenous drug use (IVDU). Data were obtained from the New York City Department of Health.

MAIN OUTCOME

The patients were divided into four groups, ages 13-40 years, 41-64 years, and 65 years and over with AIDS as a result of transfusion, and 65 years and older with AIDS as a result of IVDU. The survivals of the three transfusion-related AIDS groups were compared, as were the 65 years-and-over groups with AIDS as a result of transfusion or IVDU. AIDS-defining diagnoses between those over and under 65 years with AIDS as a result of transfusion were also compared.

RESULTS

The median survival for the three transfusion-related AIDS groups were 273 days, 58 days, and 60 days, respectively. There was a significant association between shorter survival and increasing age. This was largely due to the longer survival of the patients aged 13-40 years. There was no difference in AIDS-defining diagnosis between those over and under 65 years with transfusion-related AIDS. The survival curves of the elderly with AIDS as a result of transfusion or IVDU were not different.

CONCLUSION

Age over 40 years is an independent risk factor for poor survival among transfusion-related AIDS patients. Among the elderly, patients with transfusion-related AIDS have similar survivals to patients with IVDU-related AIDS.

Humoral aspects of anti-HIV immune responses in Zairians with AIDS: lower antigenemia does not correlate with immune complex levels

Serological patterns of anti-HIV immune responses of 150 HIV-infected (65 asymptomatic, 19 ARC, 66 AIDS) and 150 HIV-negative healthy Zairians were studied to determine the clinical significance of p24 antigen, and anti-p24 antibody, particularly in relation to p24 relative binding capacity (RBC) and circulating immune complexes (CICs). Levels of p24 antigen, anti-p24 antibody titers, and p24 RBC were evaluated by means of enzyme-linked immunosorbent assay (ELISA). Circulating immune complexes were measured by C1q-binding assay. Human immunodeficiency virus CICs were detected by polyethylene glycol (PEG) precipitation followed by 6 M guanidinium lysis, ELISA, Western blot, or radioimmunoprecipitation of the lysed precipitates. Immunoglobulin levels for IgG, IgM, IgA, and beta 2-microglobulin (beta 2-M) were quantified in all study participants by laser nephelometry and ELISA. All immunoglobulin levels were significantly elevated among HIV-positive vs. HIV-negative individuals. Immunoglobulin levels correlated well with disease progression among infected patients. Similarly, beta 2-M levels were significantly higher in HIV-positive vs. HIV-negative individuals and correlated well with progression to AIDS. Free p24 antigen in serum was detected in 1.33% of all patients. However, p24 reactivity increased to 6% (9 of 150 cases) after PEG precipitation and CIC dissociation. There was a good correlation between p24 reactivity and disease development. High titers of anti-p24 antibody (> 44,100) occurred in at least 80% of all patients, and did not correlate with disease stage. Similarly, more than 60% of patients had high levels of p24 RBC.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS: the statistical basis for public health

The backcalculation method has been extensively used in AIDS modelling and forecasting. Knowledge of reported AIDS cases, information on the time between HIV infection and onset of AIDS, and assumptions on the rate at which infections occurs, can be used to reconstruct the past history of the HIV epidemic, as well as to provide short term predictions of AIDS incidence. Uncertainty in the three components of the backcalculation method and the increasingly available information on HIV prevalence must be taken into account in order to provide realistic projections. In this paper we discuss ways of acknowledging uncertainty and suggest a Bayesian formulation of the backcalculation idea as a means of combining into a single model both random and systematic variation as well as prior information.

Splenectomy in human immunodeficiency virus-related thrombocytopenia

To evaluate the efficacy and safety of splenectomy in patients with human immunodeficiency virus (HIV)-related thrombocytopenia, 30 HIV-infected patients with thrombocytopenia (platelet count < 50 x 10(9)/l) who underwent splenectomy were followed prospectively for a mean period of 42 months. There were no perioperative deaths and morbidity was minimal. Twenty-one patients had a persistent complete response, six had a partial response and were asymptomatic after splenectomy, and only three showed no response. Three patients developed acquired immune deficiency syndrome during follow-up, an incidence that was no different from that expected. Splenectomy is a safe and effective treatment in HIV-infected patients with severe symptomatic thrombocytopenic purpura resistant to medical therapy.

Prolonged immunostimulatory effect of low-dose polyethylene glycol interleukin 2 in patients with human immunodeficiency virus type 1 infection

13 patients with human immunodeficiency virus type 1 infection class II-IV, but without opportunistic infection or neoplasm, received 6 micrograms (3.6 x 10(4) IU) of polyethylene glycol recombinant human interleukin 2 (PEG IL-2) intradermally twice a week for 4 mo were then followed for an additional 6 mo. Clinical, immunological, and viral parameters were monitored in the patients, all of whom were taking zidovudine. The cutaneous administration of PEG IL-2 resulted in an indurated zone resembling a delayed-type hypersensitivity response of 26 +/- 1 mm diameter (676 mm2) at 72-96 h after injection throughout the 4 mo of administration. This dose, which was appreciably lower than in most previous trials, was not associated with local or systemic toxicity. No increase in the viral burden of circulating leukocytes or plasma occurred. A number of immunological functions were stimulated by this course of therapy. All patients demonstrated high levels of lymphokine-activated killer cell activity by cells freshly removed from the circulation and in the absence of in vitro exposure to IL-2. Natural killer cell activity was also enhanced. Limiting dilution analysis revealed an increase in the frequency of IL-2-responsive cells from abnormally low to levels above normal during the course of injections. In a subgroup of four patients with > or = 400 CD4+ T cells/microliter at entry, there was a trend to sustained increases in CD4+ T cell numbers. However, this increase did not reach statistical significance. This subset of patients also exhibited higher proliferative responses to phytohemagglutinin as mitogen. Several of these effects persisted for 3-6 mo after cessation of therapy. In conclusion, low-dose IL-2 regimens lead to sustained immune enhancement in the absence of toxicity. We suggest pursuit of this approach for further clinical trials both as prophylaxis and therapy.

The effects of methadone on immune function among injecting drug users: a review

Methadone maintenance therapy is advocated as a major preventive strategy for the spread of the human immunodeficiency virus (HIV) and other blood-borne infectious agents among injecting drug users (IDUs) because of its effects in decreasing the frequency of injecting and presumably sharing of equipment. As an opioid agonist, methadone may share the direct and indirect immunoregulatory effects of other opioids, and thus affect susceptibility to, and the natural history of, HIV infection. Available evidence pertaining to methadone and immune function is reviewed. The long-term immunosuppression observed in heroin injectors on present (incomplete) evidence appears to be caused by factors associated with a drug-using lifestyle rather than by a direct action of heroin. Although data are conflicting, it is most likely that methadone does not significantly impair immune function and is safe for HIV-infected IDUs, possibly even allowing some improvement of immune function to occur. The increasing reliance placed on methadone maintenance to control the epidemic of HIV infection in IDUs requires that remaining uncertainties regarding methadone and immune function are clarified urgently.

The role of CD8-positive lymphocytes in the control of HIV-1 infection of peripheral blood mononuclear cells

The role of CD8-positive lymphocytes from HIV-1-seropositive individuals in the inhibition of HIV-1 replication in CD4-positive lymphocytes, either from HIV-1-seropositive or -seronegative individuals, has been described. It has been suggested that CD8-positive lymphocytes isolated from HIV-1-seropositive individuals are 'primed' against certain HIV-1 antigens, hence inducing HIV-1-specific resistance. In the present studies, we show that CD8-positive lymphocytes from HIV-1-uninfected individuals also induce a significant decrease in HIV-1 replication from peripheral blood mononuclear cells (PBMC) acutely infected with HIV-1 in vitro. Unfractionated PBMC from 16 HIV-1-seronegative individuals were infected with HIV-1. In parallel experiments, PBMC from these individuals were depleted of CD8-positive lymphocytes. Viral replication was measured by a syncytia-formation assay, as well as by measuring HIV-1 p24 antigen levels in the culture supernatants on day 10 post-infection. Removal of CD8-positive lymphocytes resulted in the increased replication of HIV-1 in vitro. Reconstitution with syngeneic CD8-positive lymphocytes to CD8-positive lymphocyte-depleted wells resulted in significant decreases in HIV-1 replication. Reconstitution with allogeneic CD8-positive lymphocytes or supernatants from syngeneic or allogeneic CD8-positive lymphocyte cultures also resulted in some decrease in HIV-1 production, but it was not statistically significant. The status of HIV-1 replication in unfractionated, CD8-positive lymphocyte-depleted and CD8-positive lymphocyte-reconstituted PBMC cultures was further confirmed at the level of HIV-1 transcription. In situ hybridization of cultured cells, with a biotinylated HIV-1 gag probe, revealed increased numbers of cells actively transcribing HIV-1-specific RNA in the CD8-positive lymphocyte-depleted cell cultures, as compared with unfractionated PBMC. Thus, removal of CD8-positive lymphocytes from PBMC obtained from HIV-1-seronegative individuals resulted in a significant enhancement of HIV-1 replication in vitro.

Planning community-wide services for persons with HIV infection in an area of moderate incidence

The human immunodeficiency virus (HIV) epidemic has placed enormous strains on health care and social services delivery. The authors studied the response to the epidemic by a local health jurisdiction in an area of moderate incidence. The area recorded about 1,000 cumulative cases of acquired immunodeficiency virus syndrome, and the estimated prevalence of HIV infection was 10,000 as of 1991. The local health jurisdiction combined methods in a community-wide planning process for HIV services. The process mobilized the existing community-based network of service providers to identify problem areas and to develop recommendations for action. The planning group used questionnaires and service use rates to project service requirements, estimate service availability, and establish levels of unmet needs in terms of units of service. Annual requirements per person with HIV infection were projected for case management (0.3 to 0.4 client enrollment slots), dental care (1.9 to 3.4 visits), nonacute institutional care (1.2 days), home health care (17.8 to 22.1 visits), short-term housing (8.3 to 10.6 days), mental health and emotional support (34.6 to 36.6 visits), legal services (2.7 appointments), acute inpatient medical care (2.0 to 3.2 days), and inpatient psychiatric care (0.2 to 0.3 days). Those service requirement estimates for a low or moderate HIV incidence area may be transferable to other communities.

IgA as a marker of clinical progression among HIV-seropositive intravenous drug users

The recognition of markers of progression towards disease in carriers of HIV is important in order to identify those who will develop AIDS and to start antiviral treatment at the appropriate time. Most studies of potential markers of progression have been made on homosexual men and haemophiliacs. We studied a population of 87 intravenous drug users (IVDUs), recruited between May 1984 and May 1986, in order to determine the usefulness of CD4 and CD8 counts as well as IgG, IgM and IgA values in predicting progression to AIDS. Eight persons developed AIDS during a median period of 44 months. Overall, the mean IgA value was lower in HIV-seropositive IVDUs than in HIV-negative IVDUs and in HIV-negative persons not using IV drugs and who acted as controls. Even so, a concentration of IgA > 2.5 g/l at enrollment was the best predictor of progression to AIDS. This finding suggests that a raised concentration of IgA may be an important early marker of progression towards disease in this population.

Early markers of HIV infection and subclinical disease progression

Human immunodeficiency virus (HIV) infection in US Air Force personnel between 1985 and 1989 was examined through a mandatory serological survey, and through annual examination of infected patients. CD4+ cell counts were determined by flow cytometry; beta 2 microglobulin and neopterin were measured by immunoassay. During this period 933 cases were found, of which 161 were documented seroconversions, giving an incidence rate of 15.6/100,000 person-years. For patients with > 400 CD4 cells microliters-1, the rate of initial occurrence of opportunistic infection was 1 and 4% at 1 and 2 years, respectively. HIV-infected persons with < 400 CD4+ cells microliters-1, in contrast, had rates of 21% at 1 year and 36% at 2 years. In a cross-sectional study, beta 2 microglobulin concentration was shown to increase in both the serum and spinal fluid of patients infected with HIV as their blood CD4 numbers declined. Neopterin levels in serum and spinal fluid showed a similar trend, with significantly lower neopterin concentrations in the group that had > 1000 CD4+ T cells compared to the 0-600 CD4+ cell group. Longitudinal studies included correlation of HIV p24 antigen with CD4 counts over a 1 year period. The p24 antigen-positive group had a 21% decline in CD4+ T cells, while the antigen-negative group had a 14% decline. Specific helper T-cell subsets were also examined over a 6 month period. A significant decline was seen in the CD4+/CD29+, CD4+/CD45R+, and overall CD4+ subsets which was not seen in AZT-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

High dose L-carnitine improves immunologic and metabolic parameters in AIDS patients

Several reports indicate that systemic carnitine deficiency could occur in acquired immunodeficiency disease syndrome (AIDS), and that primary and secondary carnitine deficiency leads to critical metabolic dysfunctions. L-carnitine supplementation to peripheral blood mononuclear cells (PBMCs) of AIDS patients resulted in significant enhancement of the phytohemagglutinin (PHA)-driven proliferative response. High dose L-carnitine administration (6 gr per day for two weeks) to AIDS patients treated with zidovudine also led to increased PBMCs proliferation and reduced blood levels of triglycerides. In addition, a reduction of beta 2-microglobulin serum levels as well as circulating tumor necrosis factor (TNF)-alpha, mostly in patients exhibiting highly elevated levels, were found at the end of the treatment period. Our data suggest that in vivo L-carnitine could prove useful in ameliorating both the immune response and lipid metabolism in patients with AIDS, irrespective of initial serum carnitines levels. The mechanism(s) accounting for the observed results are currently not clear. Further studies are needed to confirm the hypothesis that L-carnitine affects the expression of HIV-induced cytokine.

Evaluation of a dual-color flow cytometry immunophenotyping panel in a multicenter quality assurance program

A basic immunophenotyping panel that employed dual-color combinations of fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugated monoclonal antibodies (mAb; FITC-CD45/PE-CD14, FITC-IgG1/PE-IgG2, FITC-CD3/PE-CD8, FITC-CD3/PE-CD4, FITC-CD3/PE-CD16 + PE-CD56, and PE-CD19) was utilized in a quality assurance program to determine whether the 4 laboratories participating in a multicenter AIDS study obtained similar lymphocyte subset percentage values for T cells, B cells, NK cells, and CD4+ and CD8+ T cells. Over a 1 1/2 year period, 78 shared peripheral blood specimens were prepared and analyzed in each laboratory. The CD45bright CD14- percentage for each specimen was used to correct that individual's lymphocyte subset values. Interlaboratory coefficients of variation (CV) for the human immunodeficiency virus type I (HIV) seronegative (n = 38) and HIV-seropositive (n = 40) specimens using this panel were < 3% for total T cells; < 5% for CD4+ T cells and CD8+ T cells; < or = 17% for B and NK cells; and < 8% for CD4T/CD8T ratios. The 6-tube basic immunophenotyping panel has several notable features: a) for clinical studies, it permits comprehensive evaluation of an individual's major lymphocyte subsets, i.e., T, B, NK, and CD4+ and CD8+ T cells; b) for interlaboratory proficiency testing programs, it allows the detection of differences among laboratories in measurements of several functionally distinct cell populations; and c) for within-sample quality assurance, it provides several quality control checks, including the lymphosum, i.e., the sum of an individual's corrected T+B+NK values, a sum that was generally 100 +/- 5% on the HIV-seronegative specimens analyzed in this study.

The progression of untreated HIV-1 infection prior to AIDS

Using a case-control study of untreated men, we investigated the physical, mental, and economic effects of human immunodeficiency virus (HIV-1) infection prior to the diagnosis of acquired immunodeficiency syndrome (AIDS). Beginning 2 to 2.5 years prior to AIDS, case subjects reported more of 12 HIV-1 related symptoms and during the year prior to AIDS, at least 30.6 extra days of these symptoms than did control subjects. Within the 6 months preceding AIDS, case subjects' unemployment rose to 9% (P < or = .05) and depression to 34.2% (P < or = .001). At 6 to 12 months and within 6 months before AIDS, 17.1% and 31.5%, respectively, were anemic, while 37.7% and 64.7% had CD4+ counts less than 200 x 10(6)/L. Diagnosing AIDS at CD4+ counts less than 200 x 10(6)/L could significantly reduce pre-AIDS morbidity. Other implications of these findings are discussed.

Clinical manifestations and predictors of disease progression in drug users with human immunodeficiency virus infection

BACKGROUND AND METHODS

To examine the clinical course of human immunodeficiency virus (HIV) infection in injection-drug users, we conducted a prospective study of a cohort of patients in a methadone-treatment program in New York City from July 1985 through December 1990. The patients underwent standardized evaluations at base line and semiannually thereafter and received on-site primary medical care. Rates of progression to the acquired immunodeficiency syndrome (AIDS) and major outcomes before the development of AIDS were examined by univariate analyses; the risk of AIDS was also assessed by product-limit survival analysis and proportional-hazards regression.

RESULTS

Of 318 HIV-seropositive patients who did not yet have AIDS (171 men and 147 women), 90 were black, 179 were Hispanic, and 49 were white; the median age was 33 years. Over a median of 3.0 years of follow-up, 55 (17 percent) received a diagnosis of AIDS (incidence per 100 person-years, 5.8). Major outcomes before the development of AIDS included oral candidiasis (incidence per 100 person-years, 11.2), pyogenic bacterial infections including pneumonia and sepsis (8.0), pulmonary tuberculosis (1.2), multiple constitutional symptoms (13.6), and herpes zoster (1.3). There were 41 deaths from AIDS, and 13 seropositive patients without AIDS (4.1 percent) died of bacterial infections, as compared with only 1 of 411 seronegative patients studied (P < 0.001). The incidence of AIDS was 62 percent lower among those who took zidovudine than among those who did not (P = 0.02). In the multivariate analysis, progression to AIDS was best predicted by low numbers and percentages of CD4+ lymphocytes, nonuse of zidovudine, and the presence of oral candidiasis, bacterial infections, or tuberculosis. There was no consistent relation between progression to disease and the continued use of injection drugs.

CONCLUSIONS

HIV-infected injection-drug users have progression to AIDS at rates comparable to those of other HIV-infected groups, but they have substantial pre-AIDS morbidity and mortality, particularly from bacterial infections, which also appear to predict disease progression.

A new approach to estimating AIDS incubation times: results in homosexual infected men

STUDY OBJECTIVE

The aim was to develop a new approach for estimating the incubation period of acquired immunodeficiency syndrome (AIDS), based on age distributions.

DESIGN

Incubation period was expressed as the difference between age at time of diagnosis and age at time of contamination. Assuming independence between age at time of infection and incubation period, the age distribution of newly diagnosed AIDS cases is thus the convolution product between the distributions of the age of freshly infected patients and of the incubation times. AIDS incubation time can therefore be estimated from the age distribution of newly HIV infected subjects and newly diagnosed AIDS cases.

SUBJECTS

Subjects were 2220 AIDS cases diagnosed until 1987, reported to the Ministry of Health, France, and 172 subjects discovered to be HIV-1 seropositive during a blood donation in Paris between August 1985 and July 1988. In both groups, the only known risk factor was homosexuality.

MAIN RESULTS

The estimated median incubation time was 9.9 years (90% CI 9.0-10.9 years). Confidence intervals were narrow, even when taking into account the uncertainty in serodetection delay (90% CI 6.7-13.5 years).

CONCLUSIONS

The incubation estimate is as accurate as previous estimates based on other models. This technique could therefore be applied to other risk groups.

CD4 lymphocyte decline and survival in human immunodeficiency virus infection. The Military Medical Consortium for Applied Retroviral Research

The loss of the CD4 lymphocyte is the central pathophysiologic event in the progression of human immunodeficiency virus (HIV) infection. This retrospective study, based on review of data from deceased HIV patients followed in a single HIV clinic, was conducted to determine if the rate of CD4 lymphocyte decline was predictive of survival. Forty of 172 patients met defined criteria for inclusion in this study. For each patient, CD4-cell counts showed approximate exponential decline over time. A Cox regression analysis was used to assess the association of CD4 cell decline (half-life), race, age, gender, initial CD4-cell count, and treatment (anti-Pneumocystis carinii pneumonia prophylaxis and/or zidovudine vs. no therapy) on total survival (from initial CD4 cell count) and on remaining survival time after reaching a CD4 cell count of 100 (estimated). For all patients, the rate of CD4 cell decline was predictive of total survival (p = .009) but not for survival after reaching a count of 100 (p = .6). For patients who had never received therapy (6 patients), however, the CD4 half-life remained associated with survival time from 100 CD4 cells (p < .05) as opposed to the treated patients. Therapy was the single variable most predictive of both survival endpoints, resulting in an increase in median total survival of 27.2 mo (p < .00001) and of 15.4 mo from a CD4 cell count of 100 (p < .00004). Nonwhites had a slight survival disadvantage compared to whites (p = .08 overall; p = .02 from CD4 cell count of 100).(ABSTRACT TRUNCATED AT 250 WORDS)

Blocked early-stage latency in the peripheral blood cells of certain individuals infected with human immunodeficiency virus type 1

Human immunodeficiency virus type 1 (HIV-1) infections of humans have a natural history characterized by a variable but usually slow progression to an immunodeficient state. We have described a molecular model of HIV-1 proviral latency in certain cell lines, characterized by extremely low or undetectable levels of unspliced genomic HIV-1-specific RNA but significant levels of multiply spliced HIV-1-specific RNA. We have utilized a quantitative reverse transcriptase-initiated polymerase chain reaction to measure the levels of various HIV-1 RNA species in peripheral blood mononuclear cells. The median level of multiply spliced HIV-1 RNA was dramatically higher than the median level of unspliced viral RNA in asymptomatic individuals. In addition, HIV-1 RNA patterns characterized by at least a 10-fold excess of multiply spliced to unspliced viral RNA were significantly more common in asymptomatic individuals than in patients with the acquired immunodeficiency syndrome. We suggest that asymptomatic clinical HIV-1 infection is characterized by a preponderance of HIV-1-infected peripheral blood cells blocked at an early stage of HIV-1 infection. This viral expression pattern, which we have called blocked early-stage latency, may constitute a reservoir of latently infected cells in certain HIV-1-infected persons.

Cerebrospinal fluid neopterin and beta 2-microglobulin levels in neurologically asymptomatic HIV-infected patients before and after initiation of zidovudine treatment

The effect of zidovudine on beta 2-microglobulin and neopterin in the cerebrospinal fluid (CSF) was studied in ten HIV-seropositive neurologically healthy individuals. CSF concentrations of neopterin decreased by 53% (from 20.3 to 9.5 nmol/l, p < 0.01) and beta 2-microglobulin by 36% (from 2.8 to 1.8 mg/l, p < 0.01) four to eight months after initiation of therapy.

Economic impact of HIV infection and coronary heart disease in immigrants to Canada

OBJECTIVE

To compare the direct health care costs of illnesses associated with the human immunodeficiency virus (HIV) and of coronary heart disease (CHD) in immigrants to Canada.

DESIGN

Comparative cost analysis.

PARTICIPANTS

All people who immigrated to Canada in 1988. The numbers with HIV infection and CHD were estimated from country-specific HIV seroprevalence data and national CHD mortality statistics and data from the Framingham study. Health care costs, projected over the 10 years after immigration, were calculated on the basis of data from the Hospital Medical Records Institute and provincial fee schedules.

RESULTS

Of the 161,929 immigrants in 1988, 484 were estimated to be HIV positive. The total cost of treatment of HIV-related illnesses from 1989 to 1998 (discounted at 3%) would be $18.5 million: $17.1 million would be spent on the outpatient and inpatient care of the HIV-positive immigrants, $1.0 million on care of the subsequently infected sexual partners and $0.4 million on care of the HIV-positive children born to seropositive immigrant women. In comparison, CHD would develop in 2558 immigrants during the same 10-year period. The total CHD costs would be $21.6 million: $8.4 million would be spent on treating myocardial infarction, $3.2 million on coronary artery bypass grafting, $1.6 million on pacemaker insertion and $8.4 million on treating other CHD events.

CONCLUSIONS

The economic impact of HIV infection in immigrants to Canada is similar to that of CHD. This comparison identifies an important shortcoming in current immigration policy: economic considerations can be arbitrarily applied to certain diseases, thereby discriminating against specific groups of immigrants.

Zalcitabine. A review of its pharmacology and clinical potential in acquired immunodeficiency syndrome (AIDS)

Zalcitabine is an analogue of the nucleoside deoxycytidine which, when intracellularly converted to an active triphosphate metabolite, inhibits replication of human immunodeficiency virus (HIV). Zalcitabine is thought to act in the early phase of HIV replication by inhibiting reverse transcriptase and terminating the viral DNA chain. In vitro, zalcitabine is one of the more effective nucleoside analogues currently in clinical use for HIV infection, with 0.5 mumol/L concentrations completely inhibiting HIV replication in human T lymphocyte cell lines. In clinical trials, p24 antigen levels decreased and CD4 cell counts increased in patients with acquired immunodeficiency syndrome (AIDS) receiving zalcitabine > or = 0.03 mg/kg/day as monotherapy. Dose-dependent adverse effects that include peripheral neuropathy, stomatitis and rash, restrict long term use at higher dosages, and it is unclear whether zalcitabine monotherapy is as effective as zidovudine in extending survival in HIV-infected patients. Alternating or concomitant therapy with zalcitabine and zidovudine provides effective inhibition of viral replication and disease progression (as measured by improvements in CD4 cell counts) with lower and less toxic dosage regimens. At present, therefore, zalcitabine has a place in AIDS therapy both in combination with zidovudine, and as monotherapy for patients unable to tolerate zidovudine.

AIDS: Part I

Acquired immunodeficiency syndrome (AIDS) is caused by infection with a pathogenic human retrovirus known as human immunodeficiency virus (HIV). Approximately 1 million people are currently infected with HIV in the United States, with 8 to 10 million infected individuals worldwide. The virus is transmitted predominantly through genital sexual contact, although orogenital spread has been rarely reported. Heterosexual transmission has been most common in the Third World, whereas male homosexual transmission has predominated in the United States and western Europe. Transmission through homosexual contact has been steadily declining over the past 5 years as transmission through illicit intravenous drug use and promiscuous unprotected heterosexual activity has increased. Sexually transmitted diseases that cause inflammatory or ulcerative lesions of the genital tract act as important cofactors in increasing the risk of transmission through sexual contact. Perinatal transmission of HIV occurs in approximately 30% of infants born to infected mothers. Transmission to infants through breast-feeding has also been documented. Health care workers have been infected with HIV through accidental high-risk percutaneous or mucous membrane exposures, albeit at a low transmission rate of 0.3%. Infection of patients by infected health care professionals is a rare event, having been reported only once in 10 years of the epidemic. Infection with HIV results in a chronic lifelong infection. The major targets for HIV are CD4+ T-helper lymphocytes and cells of monocyte/macrophage lineage. Infection of the T-helper lymphocyte ultimately results in the death of the cell. Over time (measured in years), a progressive destruction of the T-helper lymphocyte population occurs, which results in profound immune suppression. Infection of monocytes/macrophages is not cidal, but these cells do have functional alterations as a result of the infection, which may contribute to the immune deficiency. In addition, chronically infected tissue macrophages may act as an important reservoir for HIV, particularly in the central nervous system. Infection of the T-helper lymphocytes and monocytes/macrophages is mediated through attachment of HIV through a specific binding interaction between CD4 expressed in the plasma membrane of these cells and a surface glycoprotein on the virus, gp120. Once the virus nucleocapsid (core particle) enters the cytoplasm of the target cell, the viral RNA genome is reverse transcribed by a reverse transcriptase enzyme into proviral DNA. This proviral DNA migrates into the nucleus where it integrates into the host cellular genome, which results in a chronically infected cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of prognosis and survival of the HIV-infected patient

HIV disease, once considered an acute disease with a 100% mortality rate but a very short symptomatic stage, has begun to emerge as a preventable, treatable, chronic disease. Interactions between patients, dentists, and physicians are essential to gain the information necessary to provide appropriate dental care for both short-term and long-term survivors. The prognosis and survival time of the dental patient may influence treatment protocols and necessitate modified dental procedures. Certain clinical and laboratory parameters, which may be useful indicators of disease progression, need to be recognized by the dental clinician. These parameters include systemic signs, symptoms, and serologic data as well as intraoral manifestations associated with HIV disease. Although a perfect classification system for progression of HIV disease does not exist, trends among larger cohorts may enable health care providers to estimate the prognosis and survival of HIV-infected patients on an individual basis. This article presents clinical and laboratory parameters that indicate HIV disease progression. Providers who care for HIV-infected patients need to consider these parameters to establish an appropriate and flexible treatment plan based on changes in the patient's medical status.

Nutritional alterations in persons with HIV infection

Potential relationships among nutritional status, immune function and quality of life were examined in a convenience sample of 40 outpatient homosexual and bisexual males stratified into five categories, using modified Walter Reed Staging Criteria. Nutritional status was assessed by measuring height, weight, triceps skinfold thickness, arm circumference, nutrient intake and serum albumin. Immune status was evaluated by determining T-helper cell numbers and percentages. The Quality of Life test was used to obtain information about life quality. Nutritional assessment failed to show significant differences among groups with the exception that serum albumin levels were reduced in persons with AIDS. The significance of change in serum albumin in regard to nutritional status is unclear, since serum albumin is affected by a number of non-nutritional factors, such as hydration status and liver function. The study also revealed a significant decline in T-helper percentages, but not absolute T-helper cell numbers as a function of disease stage. There were no statistically significant differences between the quality of life scores with respect to each grouping. These data suggest that asymptomatic patients as well as those with ARC or stable AIDS are able to maintain body weight and composition.

Cardiac surgery in patients with human immunodeficiency virus infection: indications and results

Ten patients with human immunodeficiency virus (HIV) infections underwent cardiac surgery using cardiopulmonary bypass. All were in Centers for Disease Control (CDC) group II. The cardiac involvement was either urgent or severely symptomatic in all cases. One patient died due to acquired immunodeficiency syndrome (AIDS) unrelated cause. No complications were encountered in this series. Eight of the nine survivors were available for follow-up. Three of these eight patients progressed to AIDS (CDC group IV) and subsequently died. Five patients are alive and in CDC group II. Prognosis of the HIV infection and the natural history of the cardiac disease are the two main elements to be considered whenever cardiac surgery is required.

Interpreting pharmacoeconomic and quality-of-life clinical trial data for use in therapeutics

Interpretation of quality-of-life (QOL) and pharmacoeconomic data for therapeutic decision making and therapeutic policy planning requires a basic understanding of the methods, assumptions and limitations of the data and associated methods of analysis. Measures of the effectiveness of different pharmaceutical agents can be modified by including functions which involve assessment of the treated individual's quality of life. These quality-adjusted effectiveness measures will alter conclusions concerning clinical decisions as well as the cost-effectiveness of the comparative agents under consideration. To provide a conceptual and analytical framework for understanding the relationship between QOL assessment and pharmacoeconomic modelling, interpretations of the quality-adjusted analyses are reviewed, conceptual and analytical models are proposed, and recommendations for using QOL data in pharmacoeconomic models are outlined. Techniques for incorporating QOL measures in pharmacoeconomic models are examined using a hypothetical model involving therapeutic assessments of antiviral treatments for individuals with HIV disease. Adjustments of effectiveness measures based upon QOL-related functions are then globally addressed using stochastic compartmental models. Three specific methods for adjustment used in therapeutic trials are reviewed. Applications of these techniques to 3 studies involving the treatment of HIV disease and hypertension are critically reviewed. Issues relevant to choosing or estimating measures of quality of life for use in pharmacoeconomic models are summarised, and research guidelines are proposed.

Eight year prospective study of HIV infection in a cohort of homosexual men--clinical progression, immunological and virological markers

Three hundred and fourteen homosexual/bisexual men at risk for human immunodeficiency virus (HIV) infection (170 seroprevalent HIV-positive, 144 seronegative) were prospectively studied over 8 years to assess rates of HIV infection and disease progression, in conjunction with cellular and HIV serological markers. In HIV-positive subjects, CD4+ lymphocyte counts rose strikingly during the period surrounding seroconversion, then fell progressively over the intervening period to a mean level of 300 cells/mm3 when AIDS developed. Changes in CD8+ lymphocyte counts were less consistent. The trend for HIV serological markers over the study period was of progressive decline in the proportion of subjects with anti-p24 antibody, associated with an increase in the proportion of subjects with detectable HIV antigenaemia. However, only 45% of subjects tested had lost anti-p24 antibody by the time of AIDS diagnosis, and HIV antigen was detectable up to 4 years before this. Different HIV serological patterns were also observed in subjects presenting either with Kaposi's sarcoma or opportunist infections. Our data support the continued use of cellular and virological markers in the evaluation of HIV disease; however, the variability observed in this study highlights their limited ability in predicting specific clinical events. Care should therefore be taken to encompass both clinical and laboratory information in the medical assessment of the HIV-infected individual.

Survival and disease progression in human immunodeficiency virus-infected women after an index delivery

OBJECTIVE

Our objective was to provide information on survival and disease progression in human immunodeficiency virus antibody-positive pregnant women undergoing prospective evaluation.

STUDY DESIGN

After an index delivery, 103 human immunodeficiency virus antibody-positive pregnant women were identified and underwent follow-up for 3 years. The patients were assessed medically and/or gynecologically when hospitalized for a human immunodeficiency virus-related illness or at each follow-up visit. The life-table method was used to estimate the cumulative probabilities of survival and remaining free of acquired immunodeficiency syndrome. Cox's proportional-hazards analyses were used to identify prognostic factors for survival and progression to acquired immunodeficiency syndrome.

RESULTS

The majority of human immunodeficiency virus-infected pregnant women were alive 3 years later. Lymphadenopathy syndrome or herpes genitalis was significantly associated with a subsequent diagnosis of acquired immunodeficiency syndrome. Of the 103 original patients, six had acquired immunodeficiency syndrome at the index delivery and acquired immunodeficiency syndrome developed in 24. Approximately 94% of evaluable patients with development of acquired immunodeficiency syndrome had CD4-lymphocyte counts < 200/mm3. The most common opportunistic infection was Pneumocystis carinii pneumonia. Acquired immunodeficiency syndrome and postpartum zidovudine therapy were independent prognostic factors affecting survival.

CONCLUSION

Survival was affected by Centers for Disease Control group status of human immunodeficiency virus infection at the index delivery.

Immune changes in HIV-1 infection: significant correlations and differences in serum markers and lymphoid phenotypic antigens

Human immunodeficiency virus type 1(HIV-1) induces extensive immune cell alterations which can be detected by changes both in serum levels of soluble immune activation products and in several lymphoid phenotypic markers. The current studies were conducted in 70 HIV-1 seropositive subjects to determine whether changes among four important serum immune activation markers (neopterin, beta-2 microglobulin, soluble CD8, and soluble IL-2 receptor) and seven lymphoid phenotypic markers (CD38, HLA-DR, CD57, CD11b, CD45RA, leu8, and CD71) reflect similar or disparate aspects of immune pathology. On the basis of correlation coefficient calculation, four groups of related markers (Fig. 1) were identified: Group A, sIL-2R was related to group B where serum neopterin, beta 2M, sCD8 levels, and lymphocyte CD38 antigen expression correlated closely. Loss of CD45RA or Leu 8 antigens in group C correlated with group B and D markers increase. HLA-D in group D was a more distantly related immune activation marker. Phenotypic markers CD57, CD11b, and CD71 did not correlate with the immune activation processes reflected by the serum and phenotypic marker groups A-D. Correlations between serum and certain lymphoid phenotypic markers were generally stronger later in HIV-1 infection when CD4 levels were less than 500/mm3. This study provides information for selecting markers for investigating immune changes in HIV-1 infection and immune-related diseases. Many serum and lymphoid phenotypic markers reflect related aspects of immune dysregulation. However, some markers can indicate different aspects of disease.

Prevalence of HIV-1 antibodies in drug addicts autopsied at the University Institute of Forensic Pathology in Copenhagen 1988-1991

In the period 1988-1991 the HIV-1 antibody test was performed in a total of 389 autopsied drug addicts. The HIV-1 incidence rose from 6% in 1988 to 14% in 1990 and 14% in 1991. There was no significant difference between the cumulated incidence in males and females. The HIV-1-positive addicts were compared to the HIV-1 negative addicts as regards mean age, duration of abuse, residence and cause and manner of death. Except for residence, where significantly more HIV-1-positive than negative addicts lived in Copenhagen, there were no significant differences between the two groups. In about one-third of the HIV-1-positive cases, equal both for males and females, the HIV-1-positivity was not known beforehand. The results are discussed in relation to the findings in other countries and to the findings in selected groups of living addicts in Copenhagen. It is concluded, that the diagnosis of HIV-1 infection in autopsied drug addicts is important from epidemiologic and hygienic points of view.

Serum beta 2-microglobulin and prediction of progression to AIDS in HIV infection

Identification of laboratory tests that can help predict progression to acquired immunodeficiency syndrome (AIDS) in people infected with human immunodeficiency virus (HIV) is important for clinical management and counselling. We have assessed the usefulness of CD4 lymphocyte count, serum beta 2-microglobulin concentration, and the presence of p24 antigen as predictors of AIDS. We studied 214 homosexual and bisexual men with well-defined dates of HIV seroconversion. For each participant, we defined the baseline date as the earliest date before the development of AIDS on which the three laboratory tests were done. beta 2-microglobulin concentration at baseline was in all analyses an independent predictor of AIDS, even after stratification by baseline CD4 count, duration of HIV infection, or use of zidovudine before or at baseline. For example, among men with at least 0.5 x 10(9)/l CD4 cells who were negative for p24 antigen, the risks of AIDS at 12 months and 24 months were 1% and 5%, respectively, for those whose beta 2-microglobulin concentrations were below 4.0 mg/l, compared with 17% and 27%, respectively for those with beta 2-microglobulin concentrations above that cut-off point (p less than 0.001). Among men with an estimated duration of infection of 5 years or less, beta 2-microglobulin concentration was the strongest independent predictor of AIDS. Measurement of serum beta 2-microglobulin adds important prognostic information to CD4 count in determining the risk of progression to AIDS in HIV-infected subjects, including those whose CD4 cell count has not yet fallen.

Different lymphoid cell populations produce varied levels of neopterin, beta 2-microglobulin and soluble IL-2 receptor when stimulated with IL-2, interferon-gamma or tumour necrosis factor-alpha

Immune activation is central to many immune disorders. Clinical investigations have shown that immune activation can be quantified by measurements of soluble immune activation products in serum. Most in vitro studies of these immune activation products have focused on single products. In this study the specific cell sources and the major lymphokines inducing multiple activation products were investigated. In vitro addition of interferon-gamma (IFN-gamma) or IL-2 stimulated peripheral blood mononuclear cells to produce neopterin, beta 2-microglobulin (beta 2-M) and soluble IL-2 receptor (sIL-2R). These two lymphokines can act independently, because neutralizing antibodies to one of the lymphokines did not block the inducing activity of the other. Tumour necrosis factor-alpha (TNF-alpha) was also investigated and shown to be a less powerful inducer than IL-2 or INF-gamma. Separated lymphoid subpopulations responded differently to specific lymphokines. Monocytes produced only neopterin and only in response to INF-gamma. T cells released beta 2-M and sIL-2R in response to IL-2. B cells, however, were capable of producing all three immune activation products. Neopterin production in B cells was induced by either INF-gamma of IL-2, indicating that B cells have additional mechanisms for responding to lymphokines. To investigate whether these in vitro findings also occur in vivo, sera from patients who had received either rIL-2 or INF-gamma treatment were tested. INF-gamma administration led to substantial increases in serum neopterin but only a moderate beta 2-M increase and no increase in the serum sIL-2R levels. rIL-2 administration caused a substantial increase of all three serum immune activation products, consistent with our in vitro findings. The results confirm that increased serum levels of soluble immune activation products are indicators of increased cytokine production by lymphocytes and monocytes and also that B cells can be a prominent source of immune activation products.

Cytomegalovirus (CMV) infection, CD4+ lymphocyte counts and the development of AIDS in HIV-1-infected haemophiliac patients

After a maximum of 11 years (median 8.3 years) from the time of HIV seroconversion, 25 out of 59 (42%) of CMV-seropositive haemophiliacs had progressed to AIDS, as opposed to eight out of 50 (16%) CMV seronegatives. The age-adjusted relative risk for AIDS among CMV seropositives was 2.4 (P = 0.03). In order to determine how this adverse effect is mediated, the mean rate of decline in serial CD4+ lymphocyte counts was studied. CD4+ lymphocyte counts tended to decline more rapidly in CMV seropositives than in seronegatives (-0.087 x 10(9)/l per annum versus -0.082 x 10(9)/l per annum), but this difference did not reach statistical significance. The average CD4+ lymphocyte count at the time of HIV seroconversion was estimated to be similar in CMV seropositives and negatives, because in HIV-1-negative haemophiliacs the CD4+ counts were virtually identical, after adjustment for age (0.94 x 10(9)/l and 0.97 x 10(9)/l, respectively). The median CD4+ cell count at which AIDS developed was higher in the CMV-seropositive group (0.07 x 10(9)/l) than in the seronegative group (0.04 x 10(9)/l), but this difference did not reach statistical significance. We conclude from these findings that the adverse effect of CMV is not wholly mediated via a more rapid loss of CD4+ cells. We discuss other processes that may be mediated by CMV, such as a functional deficiency of residual CD4+ cells, or dissemination of HIV in other organs, which may be important in determining the earlier onset of AIDS among CMV-seropositive subjects.

HIV-1 reverse transcriptase inhibiting antibody titer in serum: relation to disease progression and to core-antibody levels

A new assay for detecting inhibition of reverse transcriptase activity (the RT-i REA) was developed. This assay was standardized for screening serum samples for reverse transcriptase inhibiting antibodies (RT-iAb). High specificity (100%) and sensitivity (greater than 98%) were achieved with samples from HIV-negative individuals and HIV-infected individuals. The RT-i REA was also used in a study of the titers of RT-iAb in serum samples obtained from 33 HIV-infected homosexual men. The results confirmed the relation between decreasing RT-iAb levels and progression to late stages of the disease. Furthermore, a falling RT-iAb titer was observed in 14 of 15 individuals experiencing periods of severe clinical symptoms attributed to HIV-activity. In 7 of the patients the decline in RT-iAb titer began prior to severe clinical symptoms. The fall in RT-iAb titer also correlated with a reduction in core Ab level. The core Ab level has previously been reported to be a disease progression marker with considerable prognostic value. However, whereas all patients were positive for RT-iAb, 8 of the 33 patients did not have detectable core Ab. The use of RT-iAb titer as a marker of disease progression is discussed.

Using serial observations to identify predictors of progression to AIDS in the Toronto Sexual Contact Study

The Toronto Sexual Contact Study comprises a cohort of 249 male sexual contacts of men with HIV disease which has been followed every 3 months for almost 5 years. On enrollment 143 were seropositive and 16 seroconverted during the follow-up period. By 31 December 1989, 41 of the 159 seropositive cohort members had developed AIDS. Using Cox relative risk regression models, we investigated the association of a number of laboratory and clinical variables and progression to AIDS. Fixed covariate models examined laboratory variables from the enrollment visit of cohort members, with time calculated from this date. In models assessing time dependent covariates, time was calculated from the estimated date of HIV infection. In the univariate models of either fixed or time dependent covariates, many variables were significantly associated with risk of progression to AIDS (T4 cell count, T4/T8 ratio, blastogenic responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen, serum IgA, appearance of p24 antigen, and the development of oral hairy leukoplakia, thrush, or herpes zoster). Appearance of persistent generalized lymphadenopathy was not associated with increased risk of progression. In the multivariate model which evaluated fixed laboratory covariates, T4/T8 ratio, IgA level, and PHA response at enrollment were significantly associated with elevated risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological abnormalities in haemophiliacs

10 years ago, it became apparent that haemophiliacs were developing diseases which were indicative of underlying immunodeficiency. The results of investigation confirmed that many had abnormal immune systems, particularly with regard to cell-mediated immunity. These abnormalities were thought to be a consequence of the use of clotting factor concentrates, and indeed the discovery of HIV and its mode of transmission, confirmed these suspicions. However, it subsequently became clear that HIV infection did not explain all the abnormalities observed. Many in vivo studies have shown that the immune systems of HIV-negative haemophiliacs are not entirely normal, and in vitro studies have shown that clotting factor concentrates per se have a modulating effect on immune function. We have reviewed particularly the abnormalities seen in HIV-negative haemophiliacs and their possible causes, as well as the specific features of HIV infection in haemophiliacs.

Efficient replication of human immunodeficiency virus type 1 requires a threshold level of Rev: potential implications for latency

The Rev protein of human immunodeficiency virus type 1 (HIV-1) is essential for the expression of the structural genes of HIV-1. To determine whether a functional threshold level of Rev is required to allow efficient HIV-1 replication, CD4-positive HeLa cells, constitutively expressing a Rev-deficient provirus, were transfected with various quantities of a Rev-expressing plasmid. Compared with the quantity of the Rev-producing plasmid transfected, HIV-1 replication was distinctly nonlinear as measured by HIV-1 p24 antigen and HIV-1-specific RNA production. A quantitative RNA polymerase chain reaction (PCR) demonstrated that Rev mRNA expression was linearly correlated with the quantity of Rev-expressing plasmid which was transfected into these cells. These data suggest that a critical threshold of Rev is required for a highly productive HIV-1 infection. This threshold level of Rev may be involved in the generation and maintenance of HIV-1 proviral latency.

Variability in serial CD4 counts and relation to progression of HIV-I infection to AIDS in haemophilic patients. Transfusion Safety Study Group

OBJECTIVE--To examine the CD4 count and its near term changes relative to progression to AIDS within 30 months and to subsequent CD4 counts. DESIGN--Longitudinal clinical and laboratory study. SETTING--Haemophilia treatment centres in six large American cities. PATIENTS--555 people with congenital clotting disorders who were infected with HIV, initially without AIDS, and seen at follow up for 6-30 months in 1986-9. MAIN OUTCOME MEASURES--Absolute CD4 counts and incidence of AIDS. RESULTS--Outset CD4 count and age were independently related to progression to AIDS (p less than 0.0001 and p less than 0.005 respectively). Patients with CD4 counts of 0.30-0.49 x 10(9) cells/l had an age adjusted risk of AIDS within 30 months of only 9% that of patients with counts less than 0.20 x 10(9)/l. Children under 10 years old had only 16% of the CD4 adjusted risk of AIDS of people aged greater than or equal to 45 years. Analysis of 149 patients' CD4 counts at the beginning and end of two successive six month intervals showed an average decrease of 11% in each six months regardless of the outset count (greater than or equal to 0.20 x 10(9)/l). For individual patients the decrease in the second six month period was unaffected by the decrease in the first six month period. CONCLUSIONS--Antiviral treatment of asymptomatic people, particularly children, with CD4 counts greater than or equal to 0.3 x 10(9)/l is questionable if predicted on near term progression to AIDS. Because of individual CD4 count variability and the low rate of progression to AIDS near term declines in individual CD4 counts are a poor index for identifying people who will rapidly progress to AIDS.

Lack of evidence of occult human immunodeficiency virus in seronegative individuals at very high risk of infection

Reports of human immunodeficiency virus (HIV) infection in seronegative individuals prompted the authors to investigate subjects who are at very high risk of acquisition of HIV in San Francisco. Nine HIV seronegative subjects were evaluated extensively, eight of whom were drawn from a well-characterized cohort of seropositive and seronegative homosexual men who have been followed prospectively since 1983-1984. These men have calculated probabilities of infection based on a fitted model of between 0.22 and 0.94. One additional subject is an intravenous drug user who has shared needles with HIV-infected individuals extensively. Peripheral blood lymphocytes and monocytes were separately cultured from each subject and evidence of HIV infection was sought by a reverse transcriptase assay, enzyme immunoassay, and immunocytofluorographic analysis for HIV antigens, in situ hybridization, RNA slot blot analysis, and polymerase chain reaction amplification of HIV cDNA. Uncultured monocytes and lymphocytes from each donor were also examined by these techniques. Evidence of HIV infection was not found in the peripheral blood mononuclear cells of these high risk individuals.