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

The effect of CMV infection on progression of human immunodeficiency virus disease is a cohort of haemophilic men followed for up to 13 years from seroconversion

The effect of prior infection with cytomegalovirus (CMV) on progression of HIV disease in a cohort of 111 men with haemophilia was studied after 13 years follow-up. The relative hazards associated with CMV positivity on progression to AIDS, death and a CD4 count of 0.05 x 10(9)/l were 2.28, 2.42 and 2.34, respectively. CMV seropositive patients were significantly older than the seronegative and this was controlled for by using a Cox proportional hazards model. The relative hazards for the three endpoints decreased to 1.89, 1.82 and 1.93 respectively and were marginally non-significant (P = 0.05, 0.08 and 0.08 for the three endpoints respectively). We conclude that this cohort continues to show evidence of a 'co-factor' effect associated with prior infection with CMV which is confounded by age but not completely explained by age differences. The potential biological significance of these results is discussed in the context of recent controlled clinical trials which show a survival benefit from long-term high-dose acyclovir, a drug with activity in vivo against CMV and other herpesviruses.

Correlates of stress in HIV disease

A group of 53 men with HIV disease participated in this correlational study of the relationships among psychological distress, quality of life, uncertainty, coping patterns, stress, and CD4+ T-lymphocyte levels. Meaningful correlations (r > .40, p < .01) indicated that higher levels of negative-impact stressful experiences were associated with more frequent use of emotion-focused coping; both higher levels of negative stress and more frequent use of emotion-focused coping were associated with lower quality of life, higher psychological distress, and more uncertainty; lower quality of life was associated with higher psychological distress and more uncertainty; and lower CD4+ counts were associated with higher levels of positive-impact stressful experiences.

The possible roles of sperm and sperm antibodies in the pathogenesis and treatment of AIDS

Intravenous injections of donor sperm may possibly be of value to AIDS patients. The immunological basis for this proposal is reviewed in detail. Donor sperm introduced into the blood of a healthy patient produces anti-sperm antibodies which may become attached to the T-cells and cause their depletion. Reintroduction of donor sperm into the blood of an AIDS patient may reverse the pathogenesis by the donor sperm combining with anti-sperm antibodies so allowing the T-cells to recover. HIV is just the most common among the occupational viral infections of AIDS patients. A clinical trial is proposed.

Factor VIII, HIV and AIDS in haemophiliacs: an analysis of their relationship

In this review, the association between the Acquired Immune Deficiency Syndrome (AIDS) and haemophilia has been carefully examined, especially the data that have been interpreted as indicating transmission of the human immunodeficiency virus (HIV) to the recipients of purportedly contaminated factor VIII preparations. In our view, the published data do not prove the hypothesis that such transmission occurs, and therefore HIV cannot account for AIDS in haemophiliacs.

Prognostic value of adenosine deaminase compared to other markers for progression to acquired immunodeficiency syndrome among intravenous drug users

This study was designed to determine the prognostic value of erythrocyte adenosine deaminase (ADA) as a possible indicator of progression to AIDS, and compare this with other known cellular and serological markers. At the end of a 3-year study, a cohort of 114 human immunodeficiency virus-1 (HIV-1) seropositive intravenous drug users (IVDUs) from the five different Center for Disease Control (CDC) groups was examined in order to estimate the prognostic relevance with respect to the progression to acquired immunodeficiency syndrome (AIDS) of each of the following markers at baseline value: number and percentage of CD4+ T cells, number of CD8+ T cells, CD4+/CD8+ ratio, IgA and beta 2 microglobulin and ADA levels, and the presence of HIV antigens. Moreover, 57 IVDUs belonging to II and III CDC groups were analyzed in a follow-up study at 6-month intervals, in order to evaluate and compare the behavior of each marker over time. The prognostic significance of each marker was assessed by computing the survival distribution and the Cox analysis in a multivariate model providing the set of markers with greatest predictive value. The levels of ADA and the CD4+/CD8+ ratio showed a linear association with disease staging, whereas beta 2 microglobulin and CD4+/CD8+ ratio were the best predictors for AIDS progression. A highly significant increase in ADA and beta 2 microglobulin was observed during follow-up. The results obtained among HIV-positive IVDUs clearly indicate that the erythrocyte ADA may be considered a reliable marker of the development of HIV infection from the intermediate stages of the disease onwards.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of human immunodeficiency virus type 1 p24 in serum by an ultrasensitive enzyme immunoassay, the two-site immune complex transfer enzyme immunoassay

Human immunodeficiency virus type 1 (HIV-1) p24 antigen was measured by an ultrasensitive enzyme immunoassay (two-site immune complex transfer enzyme immunoassay). The antigen was reacted simultaneously with 2,4-dinitrophenyl-biotinyl-bovine serum albumin-anti-recombinant p24 (rp24) Fab' conjugate and anti-rp24 Fab'-beta-D-galactosidase conjugate. The complex that was formed, comprising the three components, was transferred from polystyrene beads coated with affinity-purified (anti-2,4-dinitrophenyl group) immunoglobulin G (IgG) to polystyrene beads coated with streptavidin. The detection limit of rp24 was 2.4 fg (0.1 amol) per assay or 0.24 pg/ml with as little as 10 microliters of serum. When sera were treated at low pH, p24 was detected in 34 (68%) of 50 serum samples from asymptomatic carriers, in 25 (86%) of 29 serum samples from patients with advanced HIV-1 infection, and in none of 117 serum samples from HIV-1-seronegative individuals. Levels of p24 in serum were inversely correlated to those of anti-HIV-1 p24 IgG, and the recovery of rp24 added to serum decreased to zero with increasing levels of anti-HIV-1 p24 IgG in serum. This sensitive method may be used as a powerful tool for investigating the disease.

Three-colour flow cytometric immunophenotyping in HIV-patients; comparison to dual-colour protocols

Flow cytometric measurement of circulating CD4+ lymphocytes is important in the evaluation of disease progression in HIV-infected patients. Development of dyes that can be exited at 488 nm and have emission maximum in the far red area has made three-colour protocols, together with fluorescein isothiocyanate (FITC) and R-phycoerythrin (PE), possible in most clinical flow cytometers. We report here the comparison of a two-tube, three-colour protocol (including CD45/CD4/ CD3 and CD8/CD4/CD3) with our conventional dual-colour protocol. No significant differences were found between percentage of CD3+ lymphocytic cells determined with three different antibody combinations. When the CD8/CD4/CD3 combination was used a systematic overestimation of CD3+ CD4+% cells was found. This turned out to be caused by the formation of 'CD8-escapees'. These are clumps of CD8+ cells that fall outside the lymphocyte gating region, principally because of high side scatter. The problem can be overcome by rigorous vortexing to loosen aggregates. The lymphocyte gating principle used in this protocol (gating on a side scatter/CD45 dot plot) is readily applicable to other antibody combinations. This was demonstrated by measuring CD5+ B lymphocytes, a subset receiving increasing attention in the study of HIV-induced immune deviations. We conclude that our three-colour protocol for CD4+ T-lymphocyte determinations offers significant advantages to the conventional dual-colour method, and we suggest that when possible anti-CD45 be added to dual-colour combinations in order to improve lymphocyte gating.

Detection of p24 antigen with and without immune complex dissociation for longitudinal monitoring of human immunodeficiency virus type 1 infection

Sequential specimens obtained from 87 multicenter AIDS cohort study participants were tested by three p24 antigen tests. They included a polyclonal enzyme immunoassay (EIA), a monoclonal EIA, and a monoclonal EIA after immune complex dissociation (ICD) of specimens. Subjects were grouped into two categories defined by real-time testing with the polyclonal EIA: 39 had become positive for p24 antigen (antigen converters) during follow-up, and 48 had progressed to AIDS without detectable antigenemia. Twenty-four (61%) antigen converters were positive by ICD-monoclonal EIA about 1 year earlier than by monoclonal EIA. In contrast, only 12 (25%) patients who progressed to AIDS without detectable antigenemia became positive by ICD-p24 EIA before developing AIDS. Thus, the main benefit of ICD treatment may be to detect p24 antigenemia approximately 1 year before the regular assay rather than to identify additional antigenemic people. Quantitative plasma RNA levels were also determined in longitudinal samples from 20 antigen converters and 7 men who developed AIDS without antigenemia. Although mean human immunodeficiency virus type 1 RNA levels were higher in antigen-positive than in antigen-negative samples (P = 0.002), more than half (11 of 20) of the antigen converters had no measurable change in human immunodeficiency virus type 1 RNA associated with change to antigen positivity.

Associations between maternal and fetal serum levels of immune activation markers and fetal growth

During pregnancy, signs of maternal immunologic sensitization to fetal HLA and other fetoplacental alloantigens are often detectable in peripheral blood. Presumbly, this in part reflects immune activity at the maternal-fetal interface. This response may involve activation of maternal T cells, which stimulate placental growth via lymphokine production. To shed light on this mechanism, data on placental weight, neonatal anthropometry, gestational age, fetomaternal HLA relationships (reflecting a potential for HLA allosensitization), and serum levels of three immune activation markers in maternal and cord blood were collected in a sample of 61 primiparous women and their neonates. The activation markers were soluble CD8 antigen (sCD8), interleukin-2 receptor (sIL-2R), and beta-2 microglobulin (β₂ m). Mean fetal and maternal sCD8 and β₂ m levels, and mean fetal sIL-2R levels were significantly higher than published norms. Fetal means for all three markers exceeded maternal means, and both sIL-2R and β₂ m were highly correlated between mother and fetus. This suggests that fetal sIL-2R and β₂ m levels result in part from transport or diffusion from the maternal compartment. No associations were found between fetomaternal HLA relationships, activation markers, and placental weight. The difference between the fetal and maternal β₂ m value was significantly correlated with birth weight, controlling for chest circumference and crown-heel length. Associations between birth weight and fetomaternal HLA relationships could not be interpreted with certainty. These findings suggest that maternal immune activation and diffusion or transport of β₂ m into fetal compartment enhances fetal growth in fat-free body mass. © 1995 Wiley-Liss, Inc.

Aqueous and serum β(2)-microglobulin levels in patients with senile cataracts, and cataracts associated with uveitis or atopy

β(2)-Microglobulin (β(2) M) has been reported to be elevated in patients with a variety of neoplasms and inflammatory disorders, and is believed to be a sensitive although nonspecific marker for lymphocyte activation and/or proliferation. In order to investigate the role of inflammation in the pathogenesis of various types of cataract, the authors measured β(2)M concentrations in the aqueous humor and serum of patients with senile cataracts (82 eyes), cataracts secondary to uveitis (16 eyes) and cataracts associated with atopic dermatitis (eight eyes). In addition, measurements were made in six patients with rhegmatogenous retinal detachment (RRD) and three patients with central retinal artery occlusion (CRAO) for comparison. The average aqueous β(2)M was increased in eyes with uveitic cataracts (678 μg/1) and RRD (533 μg/1), when compared to eyes with senile cataracts (265 μg/1), atopic cataracts (309 μg/1) and CRAO (122 μg/1). However, comparison of β(2)M to albumin aqueous-to-serum ratios (protein coefficient analysis) revealed that the aqueous β(2)M elevation was specific in only uveitic cataracts, with the elevation in RRD being most likely due to breakdown of the bloodocular barrier. Higher aqueous β(2)M concentrations were also found in cataracts with a posterior subcapsular cataract component, although this was related to a higher percentage of uveitic cataracts in this group. There was no statistically significant difference found in association with a past medical history of diabetes mellitus, hypertension or heart disease. These results are discussed in the context of the pathogenesis of cataract and the role of β(2)M in inflammatory processes of the eye.

Heart muscle disease related to HIV infection: prognostic implications

OBJECTIVES

To determine the natural course of heart muscle disease in patients infected with HIV.

DESIGN

Prospective echocardiographic survey and observational study over four years.

SETTING

Edinburgh.

SUBJECTS

296 adults infected with HIV (mean age 32.7 years (range 21.5 to 67.6) drawn from all the major groups at risk of HIV infection in Britain.

MAIN OUTCOME MEASURES

Detection of myocardial dysfunction and time to death from index echocardiogram in serial echocardiography.

RESULTS

Cardiac dysfunction was identified in 44 subjects (dilated cardiomyopathy, 13; isolated right ventricular dysfunction, 12; borderline left ventricular dysfunction, 19). Dilated cardiomyopathy was strongly associated with a CD4 cell count of < 100 x 10(6)/l, in contrast with the other forms of cardiac dysfunction. During the study 12/13 (92%) subjects with dilated cardiomyopathy, 5/12 (42%) with right ventricular dysfunction, and 8/19 (42%) with borderline left ventricular function died of conditions related to AIDS. Survival was significantly reduced in the subjects with dilated cardiomyopathy compared with those with normal hearts (P < 0.001). The median survival from the index echocardiogram was 101 days (95% confidence interval 42 to 146) for the subjects with cardiomyopathy compared with 472 days (383 to 560) for those with normal hearts and a CD4 cell count of < 20 x 10(6)/l. No significant difference existed in survival for subjects with borderline left or isolated right ventricular dysfunction.

CONCLUSION

Even after adjustment for the significantly reduced CD4 cell count with which dilated cardiomyopathy is associated, the outlook for patients with HIV infection and dilated cardiomyopathy is poor. Isolated right and borderline left ventricular dysfunction are not associated with reduced CD4 cells counts and do not carry adverse prognostic implications.

Non-parametric estimation and doubly-censored data: general ideas and applications to AIDS

In many epidemiologic studies of human immunodeficiency virus (HIV) disease, interest focuses on the distribution of the length of the interval of time between two events. In many such cases, statistical estimation of properties of this distribution is complicated by the fact that observation of the times of both events is subject to intervalcensoring so that the length of time between the events is never observed exactly. Following DeGruttola and Lagakos, we call such data doubly-censored. Jewell, Malani and Vittinghoff showed that, with certain assumptions and for a particular doubly-censored data structure, non-parametric maximum likelihood estimation of the interval length distribution is equivalent to non-parametric estimation of a mixing distribution. Here, we extend these ideas to various other kinds of doubly-censored data. We consider application of the methods to various studies generated by investigations into the natural history of HIV disease with particular attention given to estimation of the distribution of time between infection of an individual (an index case) and transmission of HIV to their sexual partner.

Use of CD4 lymphocyte count to predict long-term survival free of AIDS after HIV infection

OBJECTIVE

To estimate the probability of remaining free of AIDS for up to 25 years after infection with HIV by extrapolation of changes in CD4 lymphocyte count.

DESIGN

Cohort study of subjects followed from time of HIV seroconversion until 1 January 1993. Creation of model by using extrapolated linear regression slopes of CD4 count to predict development of AIDS after 1993.

SETTING

Regional haemophilia centre in teaching hospital.

SUBJECTS

111 men with haemophilia infected with HIV during 1979-85. Median length of follow up 10.1 years, median number of CD4 counts 17. The model was not fitted for three men because only one CD4 measurement was available.

MAIN OUTCOME MEASURES

Development of AIDS.

INTERVENTIONS

From 1989 prophylaxis against candida and Pneumocystis carinii pneumonia and antiretroviral drugs when CD4 count fell below 200 x 10(6)/l.

RESULTS

44 men developed AIDS up to 1 January 1993. When AIDS was defined as a CD4 count of 50 x 10(6)/l the model predicted that 25% (95% confidence interval 16% to 34%) would survive for 20 years after seroconversion and 18% (11% to 25%) for 25 years. Changing the CD4 count at which AIDS was assumed to occur did not alter the results. Younger patients had a higher chance of 20 year survival than older patients (32% (12% to 52%) for those aged < 15, 26% (14% to 38%) for those aged 15-29, and 15% (0% to 31%) for those aged > or = 30).

CONCLUSIONS

These results suggest that even with currently available treatment up to a quarter of patients with HIV infection will survive for 20 years after seroconversion without developing AIDS.

A model-based approach to estimate the AIDS-free time distribution in homosexual men using longitudinal data

A model-based approach is developed to estimate the distribution of time from seroconversion to diagnosis with acquired immunodeficiency syndrome (AIDS) as a function of selected time-dependent covariates. The approach is applied to longitudinal data collected over 4 years of follow-up from 450 men seropositive for the human immunodeficiency virus (90 AIDS cases) and 62 seroconverters (nine AIDS cases) participating in the Chicago part of the Multicenter AIDS Cohort Study. Because of the periodic nature of monitoring, the seroconversion time is interval-censored for seroconverters and left-censored for seroprevalent cohort members; the end-point is right-censored for 413 individuals. Since serological monitoring is not continuous but only at regularly scheduled visit times, a model for the discrete hazard rate (DHR) is proposed that is a generalized linear model that relates the DHR to the covariate history through the complementary log-log link. Classification trees are used for preliminary screening of covariates to identify predictors of AIDS that should be incorporated into the DHR model. The missing seroconversion times for all men are imputed 100 times to obtain 100 completed datasets from which the parameters of the DHR are then estimated using the maximum-likelihood method. The final DHR model includes the following infection progression (marker) variables: CD4%, hemoglobin, p24 antigen, and CD4% x p24 antigen interaction. Using this DHR model, the discrete survival distribution of AIDS-free time is estimated for the given population. The jackknife procedure is used to assess the precision of the estimated survival distribution.

Immunologic status in patients infected with HIV with oral candidiasis and hairy leukoplakia

Although numerous studies of oral manifestations associated with HIV have been reported, only a few refer to the correlation of these lesions with laboratory parameters. In this study we investigated the relationships between the two most common HIV-associated oral lesions, oral candidiasis and hairy leukoplakia, with the stage of the disease, circulating CD4+ cell counts, and the presence of anti-p24 antibodies in serum and stimulated whole saliva in 43 known HIV-1-infected persons. Although oral candidiasis and hairy leukoplakia were exclusively observed in subjects who were classified as Centers for Disease Control and Prevention group IV, only the prevalence of oral candidiasis is strongly associated with circulating CD4+ counts less than 200/mm3 (p < 0.02). The prevalence of oral candidiasis and hairy leukoplakia was significantly related to the absence of anti-p24 antibodies in serum (p < 0.01 and p < 0.01, respectively), but was only statistically significant for hairy leukoplakia in stimulated whole saliva (p < 0.02). The results suggest that oral candidiasis and hairy leukoplakia in correlation with immunologic status as indicated by low circulating CD4+ cell counts and the absence of anti-p24 antibodies in serum and the loss of secretory anti-p24 antibodies in subjects with hairy leukoplakia, may constitute prognostic markers for the progression of HIV-infection to AIDS. Our results also indicate that the absence of anti-p24 antibodies is not only influenced by the low levels of circulating CD4+ cells but probably by the presence of oral candidiasis or hairy leukoplakia as well.

Serum beta 2-microglobulin in intravenous drug users and its correlation with human immunodeficiency virus infection

High levels of serum beta 2-microglobulin have been associated with human immunodeficiency virus infection and beta 2-microglobulin has been used with other serological and immunological markers for monitoring disease progression. The usefulness of beta 2-microglobulin as a prognostic marker during human immunodeficiency virus infection has been demonstrated in homosexual men and hemophiliacs; few and contradictory data have been reported in intravenous drug users. We have evaluated a cohort of 160 intravenous drug users (81 seronegative and 79 seropositive for human immunodeficiency virus infection) with normal renal function to assess whether serum beta 2-microglobulin could be used as a serological marker for monitoring infection; 78 healthy subjects were used as controls. Of 79 seropositive drug users, 54 were asymptomatic or had persistent generalized lymphoadenopathy the remaining 25 had the acquired immunodeficiency syndrome. Seropositive patients were tested for CD4+ lymphocyte number, p24 antigen and anti-p24 antibodies. A significant statistical difference was found in mean serum beta 2-microglobulin levels between seronegative and seropositive drug users. Moreover, higher levels of beta 2-microglobulin were observed in acquired immunodeficiency syndrome patients compared with asymptomatic or patients with persistent lymphadenopathy. A significant relationship was also observed between increased concentration of beta 2-microglobulin and the serological and immunological markers which indicate human immunodeficiency virus disease progression.

The acquired immune deficiency syndrome: an overview for the emergency physician, Part 1

The acquired immune deficiency syndrome (AIDS) was recognized as a distinct entity in 1981. It began as a medical curiosity affecting only several dozen individuals in a restricted segment of the U.S. population. In the 12 years since its description, AIDS has become a pandemic affecting tens of millions with cases reported from all major countries. The illness is caused by a retrovirus, termed human immunodeficiency virus (HIV). It is a blood-borne disease with sexual, parenteral, and perinatal modes of transmission. Infection with the virus can be determined by a number of serologic techniques as well as viral culture. The pathophysiology of illness is incompletely understood, but is in large part related to destruction of helper, CD4 lymphocytes. This results in immune dysfunction and the development of a variety of opportunistic infections and malignancies. A great deal has been learned over the last decade, with important advances in treatment. Zidovudine (AZT) remains the most important agent in slowing progression of the disease and has resulted in prolonging survival. All organ systems can be affected by HIV, and many clinical manifestations are protein. Fever, weight loss, and diarrhea are often encountered general symptoms. The skin is frequently involved, with Kaposi's Sarcoma the most common malignancy and a variety of fungi and viruses the most frequent cause of infection. The lung is involved in the majority of patients, with Pneumocystis Carinii (PCP) and mycobacteria emerging as the most important pathogens. A variety of treatments have demonstrated efficacy for PCP. The risk of PCP is related to the decay in CD4 lymphocytes so that prophylactic treatment is recommended when CD4 counts fall below 200. Mycobacterial infection with multiresistant organisms has complicated the management of these infections and poses new risks to health care workers. Part 1 of this two-part series on AIDS discusses the pathophysiology and clinical expression, epidemiology, laboratory testing, and the general clinical manifestations of AIDS, as well as dermatologic, pulmonary, and cardiac symptoms. Part 2 will discuss the gastrointestinal, neurologic, and ocular symptoms, as well as the treatment and management of the AIDS patient.

An index of symptoms for infection with human immunodeficiency virus: reliability and validity

The objective of this study was to evaluate the reliability and validity of a brief index to measure symptoms in individuals infected with human immunodeficiency virus (HIV). From an ambulatory clinic that specializes in the care of HIV-infected individuals at a university hospital in northeast Ohio, 148 randomly selected outpatients (predominantly homosexual men) with a broad spectrum of HIV disease were enrolled in a prospective, cohort study. In standard interviews, patients rated the frequency of 36 symptoms related to HIV infection on an ordinal scale from zero (never) to three (daily); these interviews were repeated and outcomes determined every 3 months for one year. Clinical data were abstracted from the medical record with a standard chart review. Using specific criteria, 12 symptoms were selected for the HIV Symptom Index: fatigue, fevers, headache, imbalance, paresthesias, memory loss, cough, nausea, diarrhea, sadness, sleep disturbance, and skin problems. The HIV Symptom score (the sum of frequency ratings for the 12 symptoms) ranged from 0 to 31 with a mean of 9.4 (+/- SD 6.6). The test-retest reliability was high (intraclass correlation coefficient = 0.92) as was the internal consistency (Cronbach's alpha = 0.79). The validity of the index was established with three observations. (1) The HIV Symptom Index makes clinical sense and includes a representative spectrum of symptoms of infection. (2) Symptom Index scores were greater in patients with more advanced disease and in patients who were functionally impaired. (3) The Index was responsive to changes in health as the disease progressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a rapid quantitative assay for HIV-1 plasma infectious viraemia-culture-PCR (CPID)

A simple and rapid assay for the quantification of infectious HIV-1 in plasma was developed using short-term culture and DNA PCR. This method, called culture PCR, allows detection and quantification of infectious HIV-1 viraemia within 48 hours, and measures the number of infectious cell-free HIV-1 particles, expressed as culture PCR infectious doses (CPID/ml). 42 HIV infected subjects were assessed by this method. The titres obtained by CPID closely correlated with CD4+ count and clinical status. CPID titres had significant correlation with infectious virus titre determined by conventional limiting dilution tissue-culture methods. This culture-PCR technique permits rapid assessment of infectious plasma viraemia, and is comparable to longer culture based assay methods.

Acquired immunodeficiency syndrome in the elderly

Recent data from the US show that since 1990 the number of paediatric patients with AIDS is decreasing while the number of patients with AIDS over age 50 years is increasing. To date, little attention has been given to understanding AIDS risk-taking behaviours, clinical presentations, and therapeutic needs of middle-aged and older HIV-infected individuals. Older HIV-infected individuals deteriorate more rapidly than younger patients due to an accelerated loss of CD4+ helper T cells. Despite recognised age-related physiological differences between young and elderly individuals, scant information about drug optimisation for the treatment of AIDS in older individuals is available. More data need to be collected about this group of AIDS patients, and appropriate treatment strategies designed for their special needs.

Detection of intracellular HIV in lymphocytes by flow cytometry

Various permeabilization procedures and defined gating techniques were tested in order to optimize existing flow cytometric assays and devise a specific assay for the direct detection of intracellular HIV-1 antigens in clinical blood specimens. In our optimal procedure, blood lysed with Orthomune Lysing Reagent was fixed with 3.7% formaldehyde for 10 min at room temperature and then permeabilized with 0.2% Tween 20 for 15 min at room temperature. Cells from whole blood were labeled with either FITC-anti-p18 or FITC-anti-p24 monoclonal antibodies and PE-anti-Leu M9 (CD33) in order to exclude monocytes and granulocytes from the lymphocyte gate. The assay demonstrated that mean percentages of HIV p24 antigen positive cells were increased in patients with advanced disease. The assay in its present form is useful for monitoring disease progression and for monitoring the effects of antiviral therapy in individuals, but it is not currently sensitive enough to detect consistently the low levels of HIV infected peripheral blood cells in asymptomatic individuals.

Oral manifestations associated with HIV-related disease as markers for immune suppression and AIDS

BACKGROUND

Oral lesions are common findings in HIV-related disease, but little is known about their significance in predicting immune suppression among a representative group of HIV-infected persons.

METHODS

Oral examinations were performed on 454 patients who came to an outpatient dental clinic for dental care. CD4+ cell counts were obtained within 2 months of the examination.

RESULTS

In persons with a specific lesion and a CD4+ cell count below 200 cells/mm3 the corresponding mean CD4+ cell counts and predictive values were 149.5 cells/mm3 and 69.9% for candidiasis, 143.3 cells/mm3 and 70.1% for oral hairy leukoplakia, 126.0 cells/mm3 and 69.4% for xerostomia, 51.8 cells/mm3 and 95.1% for necrotizing ulcerative periodontitis, 98.7 cells/mm3 and 87.0% for long-standing herpes simplex virus infections, 66.6 cells/mm3 and 93.6% for Kaposi's sarcoma, and 33.7 cells/mm3 and 100% for major aphthous ulcers. The mean CD4+ cell count declined with increased numbers of different concurrent lesions.

CONCLUSION

The presence of specific oral manifestations and the number of different concurrent intraoral lesions among HIV-infected persons are associated with severe immune suppression and AIDS. Oral examinations are an essential component for early recognition of disease progression and comprehensive evaluation of HIV-infected patients.

Using CD4 counts to evaluate the stages and epidemiology of HIV infection in South Carolina public clinic patients

OBJECTIVES

CD4 lymphocyte counts decrease with the duration of human immunodeficiency virus (HIV) infection. We used CD4 counts collected for clinical reasons to evaluate the stage of HIV infection and the epidemiology of recent HIV infections among attendees of South Carolina's public health clinics.

METHODS

We measured the CD4 T-lymphocyte counts of persons newly diagnosed with HIV infection April 1989 through June 1990 at South Carolina public health clinics who returned for follow-up.

RESULTS

Of 812 newly diagnosed HIV-infected health department patients, 420 (52%) had their CD4 lymphocyte counts measured. Of these 420, 51 (12%) had CD4 counts of < 200, the level below which prophylaxis for pneumocystis pneumonia prolongs survival, and 193 (46%) had CD4 counts of < 500, the level below which zidovudine may prolong disease-free survival. The highest CD4 counts (> or = 900), which are associated with more recent HIV infection, were more common in females.

CONCLUSIONS

In South Carolina, almost half of newly reported HIV-infected persons who agreed to CD4 testing at the health department might benefit from immediate drug therapy. Within this population, women may be an emerging risk group that requires specifically directed HIV prevention efforts.

Beta-2 microglobulin as a predictor of prognosis in HIV-infected men with haemophilia: a proposed strategy for use in clinical care

Whilst the prognostic value of serum beta-2 microglobulin (s-beta 2m) is well documented, the lack of a simple strategy for its use means that it is rarely ever measured in clinical practice. The prognosis associated with s-beta 2m at two different points in HIV infection, as defined by the CD4 count, was studied in a cohort of 111 men with haemophilia registered at the Royal Free Hospital School of Medicine, London. At CD4 counts of 0.5 and 0.2 x 10(9)/l, a raised s-beta 2m level was significantly associated with an increased risk of developing AIDS (P = 0.002 and 0.022 respectively, adjusted for the patient's age). Kaplan-Meier progression rates to AIDS by 4.5 years after a CD4 count of 0.5 x 10(9)/l were 57% (95% CI 32-82%) in those with s-beta 2m levels of 3 mg/l or more, but 20% (95% CI 4-36%) in those with s-beta 2m levels of less than 3 mg/l. By 3.5 years after a CD4 count of 0.2 x 10(9)/l, Kaplan-Meier progression rates to AIDS were 75% (95% CI 52-98%) in those with s-beta 2m levels of 3.8 mg/l or more, and 47% (95% CI 29-66%) in those with s-beta 2m levels of less than 3.8 mg/l. In the absence of acute viral infections, a raised s-beta 2m indicates those who will tend to progress to AIDS more rapidly than those with lower s-beta 2m levels and the same CD4 count. S-beta 2m levels in general are likely to be higher in haemophilia patients than in other, non-haemophilic risk groups. Whilst care should be taken, therefore, when applying our chosen cut-off values to non-haemophilic patients, our findings support the introduction of prophylaxis and antiviral therapies at a higher CD4 count in those with raised s-beta 2m levels relative to other patients in the same risk group whilst delaying treatment in those with lower CD4 counts, but relatively normal s-beta 2m levels.

Markers predicting progression of human immunodeficiency virus-related disease

Human immunodeficiency virus (HIV) interacts with the immune system throughout the course of infection. For most of the disease process, HIV activates the immune system, and the degree of activation can be assessed by measuring serum levels of molecules such as beta 2-microglobulin and neopterin, as well as other serum and cell surface phenotype markers. The levels of some of these markers correlate with clinical progression of HIV disease, and these markers may be useful as surrogate markers for development of clinical AIDS. Because the likelihood and timing of development of clinical AIDS following seroconversion, for any particular individual, are not readily predictable, the use of nonclinical disease markers has become critically important to patient management. Surrogate markers of HIV infection are, by definition, measurable traits that correlate with disease progression. An ideal marker should identify patients at highest risk of disease progression, provide information on how long an individual has been infected, help in staging HIV disease, predict development of opportunistic infections associated with AIDS, monitor the therapeutic efficacy of immunomodulating or antiviral treatments, and the easily quantifiable, reliable, clinically available, and affordable. This review examines the current state of knowledge and the role of surrogate markers in the natural history and treatment of HIV infection. The clinical usefulness of each marker is assessed with respect to the criteria outlined for the ideal surrogate marker for HIV disease progression.

Relationship between the tumour-associated antigen 90K and cytokines in the circulation of persons infected with human immunodeficiency virus

A tumour-associated antigen known as 90K has been found in high concentrations in the serum of patients infected with human immunodeficiency virus (HIV) even in the absence of neoplastic complications. In order to investigate the relationship between the production of 90K and soluble inflammatory mediators, we studied serum concentrations of the antigen, tumour necrosis factor-alpha (TNF-alpha), interleukin-I-alpha (IL-I-alpha), interferon-gamma (IFN-gamma), IFN-alpha, neopterin and beta 2-microglobulin (beta 2-m) in patients with non-neoplastic HIV infection at various stages of disease and in control persons. The antigen was detected in all those studied but its concentration was higher in HIV-infected patients compared with controls (P < 0.001), increasing progressively with advancing stages of disease. There was a negative correlation between concentrations of 90K and IL-I-alpha in patients in U.S.A. Centers for Disease Control groups II and III (P < 0.02) and also between that of 90K and both TNF-alpha (P < 0.01) and IL-I-alpha (P < 0.05) in control persons. The results indicate that 90K is not merely a tumour-associated antigen and that its production may be part of immune and inflammatory responses in the absence of neoplasia. The correlation between the concentrations of 90K and of some cytokines in asymptomatic patients and healthy persons suggests that 90K may be part of a network of immune and inflammatory reactants.

Intrathecal synthesis of beta 2-microglobulin and lysozyme: differential markers of nervous system involvement in patients infected with human immunodeficiency virus type 1

beta 2-Microglobulin and lysozyme were determined in paired serum and cerebrospinal fluid samples from 137 patients, using immunofluorometry and ELISA, respectively. Of these patients, 54 were infected by human immunodeficiency virus type 1 (HIV1) (including 20 AIDS dementia patients), 73 were HIV1-seronegative with neurological diseases (meningitis (n = 10), multiple sclerosis (n = 29), other neurological diseases (n = 34)) and 10 were controls. Intrathecal synthesis of beta 2-microglobulin occurred in each group. Conversely, lysozyme intrathecal synthesis was found only in meningitis (10/10) and in HIV1-infection (24/54). A pathological increase in beta 2-microglobulin intrathecal synthesis (> or = 2 mg/l) was observed in 45 patients (34 HIV1-infected patients and 11 HIV1-seronegative patients with neurological diseases). Serum concentration and intrathecal synthesis of beta 2-microglobulin were correlated only in the 20 AIDS dementia patients. The cerebrospinal fluid beta 2-microglobulin and lysozyme concentrations were correlated in the 54 HIV1-infected patients only. Blood CD4 + T-cell count was correlated negatively with beta 2-microglobulin intrathecal synthesis but not with lysozyme intrathecal synthesis. These data suggest that in the absence of any central nervous system opportunistic process the increase of beta 2-microglobulin intrathecal synthesis (> or = 2 mg/l) may be a reliable marker of central nervous system involvement in HIV1-infected patients. Intrathecal synthesis of lysozyme was related principally to HIV1-encephalitis and central nervous system opportunistic processes.

T cell activation and disease severity in HIV infection

In vitro studies have indicated that T lymphocyte activation may be of importance in the pathogenesis of HIV infection. In order to define the role of immune activation in vivo, we assessed the expression of the T cell activation markers HLA-DR and CD25 by flow cytometry in peripheral blood in relation to disease severity and the surrogate markers CD4 and beta 2-microglobulin in 157 patients with HIV infection and 53 healthy seronegative blood donors. Percentage levels of CD3+HLA-DR+ T lymphocytes were significantly higher (P < 0.0001) and percentage levels of CD3+CD25+ T lymphocytes significantly lower (P < 0.0001) in all HIV+ patients compared with controls. A significant correlation was observed between increasing percentage levels of CD3+HLA-DR+ T lymphocytes and both declining CD4 counts (r = 0.52; P < 0.001) and increasing beta 2-microglobulin levels (r = 0.56; P < 0.001). Percentage levels of CD4+HLA-DR+ and CD4+ CD25+ lymphocytes were significantly higher in all HIV+ patients compared with controls (P < 0.001). Levels of activated (HLA-DR+ and CD25+) CD4+ lymphocytes showed a significant step-wise linear increase with increasing disease severity (P < 0.001). High levels of CD3+HLA-DR+ T lymphocytes were found in a greater proportion (81.8%) of asymptomatic HIV+ patients (Centres for Disease Control (CDC) group II) than low CD4 counts (51.5%) (P < 0.001). Compared with controls, HIV+ patients had higher percentage levels of CD8+HLA-DR+ lymphocytes (P < 0.001), but similar levels of CD8+CD25+ lymphocytes. These results indicate that T cell activation is not only a consistent but also an early feature in HIV infection. Monitoring levels of activated T cells and their subsets is of value in assessing progression of HIV-related disease.

HIV-related emergencies: frequency, diagnoses, and outcome

OBJECTIVE

To study the clinical epidemiology and outcome of HIV-related emergencies, and to identify clinical predictors of HIV-related emergency hospitalizations.

DESIGN

Case series.

SETTING

Emergency facility of a tertiary care teaching hospital.

PATIENTS

350 HIV/AIDS patients followed at the authors' center.

MEASUREMENTS AND MAIN RESULTS

69 of 356 patients made 92 emergency visits with a frequency of 8% per month and 20% per quarter in a three-month study period. Forty-three visits (47%) resulted in hospitalization and contributed to 70% of total AIDS hospitalizations in the period. The five most common acute diagnoses were pneumonia (n = 22; 24%), fever (n = 15; 16%), upper respiratory infection (n = 9; 10%), cellulitis (n = 6; 7%), and gastroenteritis (n = 6; 7%). Three diagnoses accounted for 70% of acute HIV hospitalizations: pneumonia (n = 19), fever (n = 4), and sepsis (n = 4). Analysis of patient disposition as it relates to the patient's clinical presentation and HIV history using multivariate analysis yielded 1) the presence of dyspnea or cough (p = 0.015) and 2) fever with an abnormal chest x-ray (p = 0.008) as independently predictive of hospitalization.

CONCLUSION

The findings indicate that HIV/AIDS patients have a frequent need for emergency care and most HIV/AIDS hospitalizations are emergency-related. The acute problems of these patients are related to a limited number of diagnostic categories, and the presence of respiratory or constitutional symptoms with an abnormal chest radiograph are the only reliable factors predictive of hospitalization.

The effect of age on the course of experimental feline immunodeficiency virus infection in cats

Neonatal, young adult, and aged specific pathogen-free cats were experimentally infected with cat-passaged Petaluma strain of feline immunodeficiency virus. The primary stage of illness occurred 6-8 weeks following infection in cats of all ages, but it differed in severity and clinical signs. Generalized lymphadenopathy persisted for the entire 42-week study period in neonatally infected cats, was transient in young adults, but inapparent in aged cats. Only two aged cats became chronically and severely ill during the study. One aged cat died with severe necrotizing transmural enteritis, while a second developed chronic generalized staphylococcal pyoderma that was partially controlled with antibiotics. Neutropenia appeared 6-8 weeks following infection in cats of all ages, but was more severe in newborn and aged cats than in young adults. A persistent decrease in CD4+/CD8+ T lymphocyte ratios, due to both increased CD8+ and decreased CD4+ T lymphocytes, occurred in the neonatal and aged cats. Decreased CD4+/CD8+ T lymphocyte ratios in the young adult cats was due solely to decreased CD4+ T lymphocytes. Antibody response to FIV virus, as measured by ELISA to recombinant FIV p24 antigen, was lower in aged cats than the other age groups during the first 6 weeks after infection. Antibody levels were not significantly different among the three age groups thereafter. Although there are some differences between FIV infection of cats and HIV infection of human beings, age at infection influences the severity of disease in both species.

The safety of UVB phototherapy in patients with HIV infection

BACKGROUND

In patients with psoriasis and human immunodeficiency virus type 1 (HIV-1) infection, therapeutic options may be limited by their potential immunosuppressive effects. UVB radiation can activate HIV-1 gene expression in transgenic mice and in vitro. It is not known whether this viral activation leads to a clinically significant effect or if these findings can be extrapolated to humans.

OBJECTIVE

This study was performed to evaluate the safety of UVB light treatment in HIV-infected persons.

METHODS

We prospectively studied the effect of UVB phototherapy on five HIV-infected patients with psoriasis and one with pruritus. A complete blood cell count with differential count, CD4+ and CD8+ T-lymphocyte counts, serum beta 2-microglobulin and HIV-1 p24 antigen were obtained before UVB phototherapy and after 21 and 42 treatments. After every five treatments patients were evaluated for opportunistic infections, and psoriatic involvement was quantified with the Psoriasis Area and Severity Index (PASI).

RESULTS

Cumulative UVB doses ranged from 3326 to 43,364 mJ/cm2. There were no statistically significant changes in laboratory findings after 21 and 42 treatments. Of three patients without detectable serum levels of HIV-1 p24 antigen before phototherapy, only one became positive after 42 treatments. None of the six subjects had an opportunistic infection or malignancy during phototherapy. The PASI improved in all five patients with psoriasis, and the other patient noticed decreased pruritus.

CONCLUSION

Our results suggest that UVB phototherapy is efficacious in HIV-1-infected patients with UVB-responsive dermatoses and is not associated with short-term changes in immune function.

Progressive multifocal leukoencephalopathy in AIDS: a clinicopathologic study and review of the literature

We reviewed the clinical, radiographic, and pathologic features of 15 patients with the acquired immune deficiency syndrome (AIDS) and progressive multifocal leukoencephalopathy (PML). Brain tissue from 10 autopsy and 6 biopsy specimens was studied using: in situ hybridization (ISH) for JC virus (JCV), immunohistochemistry for human immunodeficiency virus (HIV) p24 antigen, and electron microscopy. Thirteen patients presented with focal neurologic deficits, while 2 presented with a rapid decline in mental status. PML was commonly the initial opportunistic infection of AIDS and produced hemiparesis, dementia, dysarthria, cerebellar abnormalities, and seizures. Magnetic resonance imaging was more sensitive than computed tomography in detecting lesions, and often showed multifocal areas of PML. CD4+ T-cell counts were uniformly low (mean 84/mm3), except in 1 patient who improved on 3'-azido-3'-deoxythymidine (AZT). PML involved the cerebral hemispheres, brain stem, cerebellum, and cervical spinal cord. The distribution of brain involvement was consistent with hematogenous dissemination of the virus. In 2 brain specimens, multiple HIV-type giant cells were present within the regions involved by PML. When co-infection by HIV and papovavirus was present, PML dominated the pathological picture. ISH for JCV showed virus in the nuclei of oligodendrocytes and astrocytes. Occasionally there was staining for JCV in the cytoplasm of glial cells and in the neuropil, the latter possibly a correlate of papovavirus spread between myelin sheaths, as seen by electron microscopy. ISH demonstrated more extensive foci of PML than did routine light microscopy.

Progress in the understanding of HIV infection: an overview

The worldwide epidemic of human immunodeficiency virus (HIV) infection will likely be considered the most important public health event of the twentieth century. During the past 15 years, a wealth of information relating to the epidemiology, diagnosis, natural history, and treatment of HIV infection has accumulated. This article details the recent progress in each of these areas.

Design of a prospective study of the pulmonary complications of human immunodeficiency virus infection. The Pulmonary Complications of HIV Infection Study Group

Because no studies have systematically described the pulmonary complications associated with early stages of infection with the human immunodeficiency virus (HIV), the National Heart, Lung and Blood Institute and the National Institute of Allergy and Infectious Diseases jointly initiated a prospective cohort study in 1987 to describe the incidence and course of lung diseases at all stages of HIV infection. This paper describes the ongoing study and highlights some of its unusual features. Six clinical centers from different geographic areas in the U.S. began enrolling participants in 1988, and the resulting cohort comprises 1353 members. HIV seropositive participants were randomized to "intensive" (pulmonary disease screening and follow-up at 3-month intervals) or "routine" (6-month follow-up intervals with annual screening) follow-up to assess the impact of these strategies on patient outcomes. New information from this complex study will lead to a broader understanding of the pulmonary diseases associated with HIV infection and will have relevance to clinical as well as epidemiologic aspects of HIV disease.

Marker-dependent hazard estimation: an application to AIDS

The acquired immunodeficiency syndrome (AIDS) results from infection with the human immunodeficiency virus (HIV). The time of infection is generally unknown since transmission usually occurs during the course of repeated sexual contacts or needle sharing. Brookmeyer and Gail describe the biases that may arise in survival analyses using the recruitment time rather than the unknown infection time as the origin in prevalent cohorts of HIV-infected individuals. We apply a non-parametric hazard estimator, introduced by Nielsen, that assumes the hazard of an AIDS diagnosis depends upon the unknown time of infection solely through the value of possibly multidimensional markers of HIV-disease progression such as CD4+ T lymphocyte cell counts. Essentially, we estimate the hazard for a specific marker value y by dividing the number of occurrences among subjects with marker measurements in a neighbourhood of y by the total risk time in that neighbourhood. We present this estimator, which relies upon kernel estimator techniques to produce a smooth estimate, within a counting process framework. We apply this method to marker data from the San Francisco Men's Health Study.

Preliminary cost-effectiveness analysis of an AIDS vaccine in Abidjan, Ivory Coast

A preliminary assessment was made of the cost-effectiveness of a hypothetical AIDS vaccine in Abidjan, Ivory Coast. A total cost of $20,079 per HIV positive case in the Ivory Coast was projected by estimating the indirect and direct costs of infection. The HIV vaccine was then estimated to increase by $5.28; the costs of a fully immunized child (plus costs of the vaccine). After using this data and taking into account that at least 5% of a cohort of vaccine-eligible infants would become HIV positive at approximately age 26, a cost-benefit analysis was undertaken varying cost, efficacy rates for the hypothetical vaccine and HIV seroprevalence rates in order to indicate at what price per individual dose of vaccine would it stop being cost-beneficial. Furthermore, the basic model was expanded to include vaccinating young adults and the added benefits associated with decreased HIV transmission especially in individuals with high risk behavior. The model was expanded to examine the effects of a changing discount rate. Because of the tremendous economic burden due to AIDS, the prospective vaccine costs at which there is no economic benefit were higher than expected.

Cardiopulmonary bypass in HIV-positive patients

To prove the hypothesis that cardiopulmonary bypass may accelerate the development of acquired immunodeficiency syndrome (AIDS) in the human immunodeficiency virus carrier, the clinical course of 40 patients positive for human immunodeficiency virus who underwent cardiac operations between 1986 and 1992 was analyzed, especially in regard to the progression to AIDS. Mean age was 30 years (range, 19 to 61 years). Thirty-four patients (85%) were intravenous drug abusers; in 4 (10%) transmission of infection was sexual, and in 2 (5%) it was through a contaminated blood transfusion. Valve procedures were performed in 38 patients (95%), mostly for endocarditis in drug addicts. Hospital mortality was 20% (8 patients). The 32 survivors have been followed up a mean of 21 months (range, 4 months to 6 years). Four patients (12.5%) experienced progression to AIDS during the follow-up period. Actuarial progression to AIDS is 5% (+/- 5%) at 1 year, 20% (+/- 10%) at 2 years, and 40% (+/- 19%) at 5 years. There have been 8 late deaths (5 due to recurrent endocarditis, 2 due to AIDS, and 1 due to overdose). Actuarial survival is 79% (+/- 8%) at 1 year, 60% (+/- 11%) at 2 years, and 48% (+/- 14%) at 5 years. The results indicate that progression to AIDS in the patient positive for human immunodeficiency virus is not accelerated by the use of cardiopulmonary bypass. The poor prognosis in these patients is mainly related to the particular pathological conditions that often affect the drug addict population.

Clinical pharmacology of zidovudine and other 2',3'-dideoxynucleoside analogues

Since the discovery of the acquired immunodeficiency syndrome (AIDS) in 1981, considerable progress has been made in the development of agents with anti-HIV activity. Zidovudine was one of the first 2'-3'-dideoxynucleosides to cause inhibition of human immunodeficiency virus (HIV) replication in vitro, by inhibiting the viral reverse transcriptase. Early trials showed that zidovudine results in clinical and immunological improvements and prolonged life in patients with AIDS or AIDS-related complex. However, haematological toxicity is the main drawback associated with zidovudine therapy. The initial recommended dose of zidovudine was 1500 mg per day, but recent studies have shown that dosages as low as 300 mg per day could be just as effective, without the severe haematological toxicity. Because zidovudine readily crosses the blood-brain barrier, it is used for the treatment of neurological diseases associated with HIV disease with some success. However, Kaposi's sarcoma does not respond to therapy with the drug. Apart from haematological toxicity, patients on long-term therapy with zidovudine may also develop resistance. Zidovudine use has also been associated with improvements in neurodevelopmental and growth velocity in HIV-infected children. The use of zidovudine as a prophylaxis has also been suggested, but the value of this is questionable. The combination of zidovudine with other agents, such as acyclovir and interferon, has a synergistic effect on the anti-HIV activity, with reduced drug toxicity. Other 2',3'-dideoxynucleoside analogues, such as dideoxycytidine (ddC) and dideoxyinosine (ddI) are effective anti-HIV agents and their use is also associated with both clinical and immunological improvements.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical utility of an enhanced human immunodeficiency virus type 1 p24 antigen capture assay

The presence of p24 core antigen in the serum of individuals with human acquired immunodeficiency syndrome has been used as one of the important prognostic markers of HIV-1 infection and also as an end point in evaluating antiviral drugs and vaccines. Unfortunately the majority of p24 antigen present in serum exists as an antigen-antibody complex and is not detected with the commercial kits currently available to measure p24 antigen. In this study, we report a simple procedure utilizing treatment of serum samples with glycine buffer (pH 1.85) to dissociate antigen-antibody complexes prior to assaying for p24 antigen. A 300% increase in the number of p24-reactive samples and a 3- to 12-fold increase in the quantity of antigen detected were observed when samples were pretreated with 1.5 M glycine buffer (pH 1.85) for 1 hr. Glycine treatment of samples did not result in non-specific positive tests and samples previously shown to be reactive remained positive. In reconstruction experiments the release of antigen was found to be inversely proportional to the amount of p24 antibody present in the serum. The percentage of HIV-1-infected patients positive for p24 antigen was clearly a function of CD4 count. Forty-nine percent of patients with more than 500 CD4 cells and 100% of patients with less than 200 CD4 were p24 positive.(ABSTRACT TRUNCATED AT 250 WORDS)