Predictors of clinical AIDS in young homosexual men in a high-risk area

Flow Cytometric-Based Analysis of Defects in Lymphocyte Differentiation and Function Due to Inborn Errors of Immunity

The advent of flow cytometry has revolutionized the way we approach our research and answer specific scientific questions. The flow cytometer has also become a mainstream diagnostic tool in most hospital and pathology laboratories around the world. In particular the application of flow cytometry has been instrumental to the diagnosis of primary immunodeficiencies (PIDs) that result from monogenic mutations in key genes of the hematopoietic, and occasionally non-hematopoietic, systems. The far-reaching applicability of flow cytometry is in part due to the remarkable sensitivity, down to the single-cell level, of flow-based assays and the extremely user-friendly platforms that enable comprehensive analysis, data interpretation, and importantly, robust and rapid methods for diagnosing PIDs. A prime example is the absence of peripheral blood B cells in patients with agammaglobulinemia due to mutations in BTK or related genes in the BCR signaling pathway. Similarly, the development of intracellular staining protocols to detect expression of SAP, XIAP, or DOCK8 expedites the rapid diagnosis of the X-linked lymphoproliferative diseases or an autosomal recessive form of hyper-IgE syndrome (HIES), respectively. It has also become evident that distinct cohorts of PID patients exhibit unique “lymphocyte phenotypic signatures” that are often diagnostic even prior to identifying the genetic lesion. Flow cytometry-based sorting provides a technique for separating specific subsets of immune cells such that they can be studied in isolation. Thus, flow-based assays can be utilized to measure immune cell function in patients with PIDs, such as degranulation by cytotoxic cells, cytokine expression by many immune cells (i.e., CD4⁺ and CD8⁺ T cells, macrophages etc.), B-cell differentiation, and phagocyte respiratory burst in vitro. These assays can also be performed using unfractionated PBMCs, provided the caveat that the composition of lymphocytes between healthy donors and the PID patients under investigation is recognized. These functional deficits can assist not only in the clinical diagnosis of PIDs, but also reveal mechanisms of disease pathogenesis. As we move into the next generation of multiparameter flow cytometers, here we review some of our experiences in the use of flow cytometry in the study, diagnosis, and unraveling the pathophysiology of PIDs.

Elevated humoral response to cytomegalovirus in HIV-infected individuals with poor CD4+ T-cell immune recovery

Some HIV-infected c-ART-suppressed individuals show incomplete CD4⁺ T-cell recovery, abnormal T-cell activation and higher mortality. One potential source of immune activation could be coinfection with cytomegalovirus (CMV). IgG and IgM levels, immune activation, inflammation and T-cell death in c-ART-suppressed individuals with CD4⁺ T-cell counts >350 cells/μL (immunoconcordant, n = 133) or <350 cells/μL (immunodiscordant, n = 95) were analyzed to evaluate the effect of CMV humoral response on immune recovery. In total, 27 HIV-uninfected individuals were included as controls. In addition, the presence of CMV IgM antibodies was retrospectively analyzed in 58 immunoconcordant individuals and 66 immunodiscordant individuals. Increased CMV IgG levels were observed in individuals with poor immune reconstitution (p = 0.0002). Increased CMV IgG responses were significantly correlated with lower nadir and absolute CD4⁺ T-cell counts. In contrast, CMV IgG responses were positively correlated with activation (HLA-DR⁺) and death markers in CD4⁺ T-cells and activated memory CD8⁺ T-cells (CD45RA^-CD38⁺). Longitudinal subanalysis revealed an increased frequency of IgM⁺ samples in individuals with poor CD4⁺ T-cell recovery, and an association was observed between retrospective IgM positivity and the current level of IgG. The magnitude of the humoral immune response to CMV is associated with nadir CD4⁺ T-cell counts, inflammation, immune activation and CD4⁺ T-cell death, thus suggesting that CMV infection may be a relevant driving force in the increased morbidity/mortality observed in HIV⁺ individuals with poor CD4⁺ T-cell recovery.

Elevated cytomegalovirus IgG antibody levels are associated with HIV-1 disease progression and immune activation

OBJECTIVE

To assess the association between cytomegalovirus (CMV) IgG antibody levels, HIV disease progression, and immune activation markers.

DESIGN

A prospective cohort study was conducted among women enrolled in a trial that was designed to determine the effect of acyclovir on HIV disease progression in Rakai, Uganda.

METHODS

The primary endpoints were progression to a CD4 T-cell count less than 250 cells/μl, nontraumatic death, or initiation of antiretroviral therapy (ART). CD4 T-cell counts, HIV viral load, C-reactive protein (CRP), and soluble CD14 levels were assessed biannually for 24 months. CMV IgG antibodies were measured at baseline among all women and annually among a subset of women who initiated ART.

RESULTS

There were 300 HIV/CMV-coinfected participants who contributed a total of 426.4 person-years with a median follow-up time of 1.81 years. Compared with the lowest CMV IgG tertile group at baseline, the highest CMV IgG tertile group was associated with an increased risk to reach a primary endpoint independent of acyclovir use, age, CD4 T-cell count, and HIV viral load at baseline [adjusted hazard ratio = 1.59; (95% CI = 1.05-2.39); P = 0.027]. Among pre-ART visits (n = 1200), women in the highest baseline CMV IgG tertile had increasing annual rates of soluble CD14 and CRP levels, which was not observed for the low CMV IgG tertile group. Compared with pre-ART visits, CMV IgG antibody levels were higher post-ART initiation, and concurrent levels remained associated with soluble CD14 and CRP during suppressive ART (n = 88 person-visits).

CONCLUSION

The magnitude of the immune response to CMV was associated with HIV disease progression and immune activation in sub-Saharan Africa.

Associations between virologic and immunologic dynamics in blood and in the male genital tract

To determine the influence of asymptomatic genital viral infections on the cellular components of semen and blood, we evaluated the associations between the numbers and activation statuses of CD4+ and CD8+ T lymphocytes in both compartments and the seminal levels of cytomegalovirus (CMV), herpes simplex virus (HSV), and human immunodeficiency virus 1 (HIV). Paired blood and semen samples were collected from 36 HIV-infected antiretroviral-naïve individuals and from 40 HIV-uninfected participants. We performed multiparameter flow cytometry analysis (CD45, CD45RA, CD3, CD4, CD8, and CD38) of seminal and blood cellular components and measured HIV RNA and CMV and HSV DNA levels in seminal and blood plasma by real-time PCR. Compared to HIV-uninfected participants, in the seminal compartment HIV-infected participants had higher levels of CMV (P < 0.05), higher numbers of total CD3+ (P < 0.01) and CD8+ subset (P < 0.01) T lymphocytes, and higher CD4+ and CD8+ T lymphocyte activation (RA-CD38+) (P < 0.01). Seminal CMV levels positively correlated with absolute numbers of CD4+ and CD8+ T cells in semen (P < 0.05) and with the activation status of CD4+ T cells in semen and in blood (P < 0.01). HIV levels in semen (P < 0.05) and blood (P < 0.01) were positively associated with T-cell activation in blood. Activation of CD8+ T cells in blood remained an independent predictor of HIV levels in semen in multivariate analysis. The virologic milieu in the male genital tract strongly influences the recruitment and activation of immune cells in semen and may also modulate T-cell immune activation in blood. These factors likely influence replication dynamics, sexual transmission risk, and disease outcomes for all three viruses.

Psychological inhibition and CD4 T-cell levels in HIV-seropositive women

OBJECTIVE

This cross-sectional study examined the hypothesis that the capacity for emotional expression is a critical moderator of the emotional support-health relationship.

METHODS

In a sample of 61 HIV-seropositive women without AIDS, coping interviews were conducted to assess HIV-specific emotional support and emotional expression and inhibition (percentage of positive/negative emotion words and inhibition words, respectively).

RESULTS

Hierarchical regression analyses revealed no relationship between availability of HIV-specific emotional support and concurrent CD4 levels and no moderation of emotional expression or inhibition. However, a higher percentage of inhibition words was associated with lower CD4 T-cell levels controlling for health behaviors, demographics, and treatment regimen (DeltaR(2)=.08, P<.05).

CONCLUSIONS

These findings are consistent with prior theory and research showing a relationship between psychological inhibition and deleterious health outcomes.

Cytomegalovirus and simian immunodeficiency virus coinfection: longitudinal study of antibody responses and disease progression

Antibody titers to rhesus cytomegalovirus (RhCMV) were prospectively analyzed over a period of 68 weeks in a longitudinal serosurvey of 17 RhCMV-seropositive rhesus macaques (Macaca mulatta) experimentally coinfected with simian immunodeficiency virus (SIV). These were compared with anti-RhCMV titers in 18 animals that were also naturally infected with RhCMV but not infected with SIV. Fluctuations in anti-RhCMV antibody titers were observed within 5 weeks of SIV inoculation, and two distinct patterns of RhCMV antibody response were observed in SIV-infected animals. Animals showing a progressive decline in anti-RhCMV immunoglobulin G (IgG) exhibited the most rapid disease progression, coincident with low anti-SIV and anti-tetanus toxoid IgG responses, high levels of p27 antigen in the plasma, and short survival. Animals exhibiting a more stable CMV-specific response after SIV inoculation had the least rapid disease course. Anti-RhCMV antibody titers in SIV-uninfected animals remained relatively stable during the period of study. Evidence that preinoculation immunologic measures predicted postinoculation outcome was equivocal.

Relation of impaired lymphocyte proliferative function to other major human immunodeficiency virus type 1-induced immunological changes

Human immunodeficiency virus (HIV) type 1 (HIV-1) induces impairment of immune function reflected in reduced lymphocyte proliferative responses. Many other immune changes are induced by HIV-1, but their relationship to lymphocyte functional defects is not known. The present study was designed to correlate functional defects with other HIV disease parameters. Cryopreserved samples from 118 HIV-1-positive subjects and 40 seronegative individuals were examined. The main findings were that impaired proliferative responses to mitogens correlated with (i) decreased cell surface expression of the interleukin-2 receptor (CD25), (ii) increased expression of HLA-DR antigens on CD4 cells, (iii) reduced CD4 and increased CD8 cell numbers, and (iv) increased levels of serum immune complex dissociated p24 antigen. However, impaired function was not associated with increased serum neopterin, beta2-microglobulin, or soluble interleukin-2 receptor or with CD38 antigen expression on lymphocytes. In summary, proliferative functional impairment correlated with some, but not all, immunological changes associated with HIV-1 infection. Most of the phenotypic markers that correlated with altered function are cell surface molecules with significant roles in lymphocyte proliferation and were associated primarily with CD4 cells, compatible with the view that dysregulation of CD4 cells is responsible for impaired function.

Immune system changes after the death of a partner in HIV-positive gay men

The objectives of this study were to determine 1) whether immune changes relevant to HIV progression occurred in HIV-seropositive men after the death of their intimate partner, and 2) whether depressed mood was associated with these immune changes. The bereaved group consisted of 39 gay men whose intimate partners had died of AIDS over the past year; the nonbereaved group consisted of 39 age- and HIV serostatus-matched nonbereaved men. Immunological parameters were assayed from blood samples drawn before and within 1 year after the death of the partner (bereaved group) or over an equivalent time period (nonbereaved group). In the HIV-seropositive bereaved men only, a significant increase in immune activation and a significant decrease in the proliferative response to phytohemagglutinin occurred after the death of the partner. These immunological changes were not explained by the use of recreational drugs, alcohol, cigarettes, or AZT. These data indicate that the death of an intimate partner in HIV-positive men is associated with immune changes that are relevant to HIV 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.

Enhanced shedding of cytomegalovirus in semen of human immunodeficiency virus-seropositive homosexual men

Site-specific shedding of cytomegalovirus (CMV) was assessed in a longitudinal study of homosexual and bisexual men. At initial testing, CMV was cultured from the semen of 33% (19 of 58) of asymptomatic and mildly symptomatic men who were seropositive for human immunodeficiency virus (HIV) at the time of entry into the study, whereas it was cultured from the semen of 17% (10 of 58) of the men who were HIV seronegative. CMV was isolated much more frequently from semen than from urine or throat washing specimens, and it was rarely recovered from stool or blood, regardless of the subject's HIV serostatus. CMV was cultured from the semen of 31% (16 of 52) of the men relatively early after seroconversion to HIV (mean, 12.8 months). CMV was persistently isolated from the semen of a greater proportion of the HIV-seropositive men than from the semen of the HIV-seronegative men during a 4.5-year follow-up period (52 of 110 - [47%] and 15 of 58 [26%] men, respectively). There was an increased relative risk for shedding of CMV in semen in association with decreased CD4+ cell numbers and increased levels of serum immunoglobulin A. However, there was no association of CMV shedding with an increased risk for the development of AIDS.

A prospective study of 115 initially asymptomatic HIV infected gay men in Stockholm, Sweden

A cohort of 115 asymptomatic gay men, all seropositive for HIV, was recruited in a health screening project in Stockholm, Sweden, between Nov. 1982 and Dec. 1983 and subsequently followed and clinically evaluated after a mean observation time of 63 months. AIDS in accordance with the surveillance definition (CDC group IV C-1 and D) developed in 34 (29.6%) of the men, while 1 (0.9%) additional man died of multiple myeloma classified as CDC group IV E. Constitutional symptoms (CDC group IV A) developed in 13 (11.3%) men, while symptoms from the central nervous system classified as CDC group IV B occurred in 1 (0.9%) additional man. Minor opportunistic infections included in the definition for CDC group IV C-2 developed in 12 (10.4%) men, while 48 (41.7%) men remained asymptomatic, with or without persistent generalized lymphadenopathy (PGL). One man who died of AIDS had been treated for malignant melanoma (MM) and one who did not fulfill the criteria for CDC group IV died of MM during the observation period. The 5-year actuarial progression rate to surveillance defined AIDS was 31.5% and to CDC group IV 53.6%. No statistically significant association was found between disease progression and a number of recorded epidemiological variables, most previous and present sexually transmitted diseases (STD) (except gonorrhoea) and the presence of PGL at entry. On the other hand, reduced delayed cutaneous hypersensitivity, in particular to tuberculin, as well as the presence of a high IgG titer against cytomegalovirus (CMV), were correlated to disease progression.

Quality control in the flow cytometric measurement of T-lymphocyte subsets: the multicenter AIDS cohort study experience. The Multicenter AIDS Cohort Study Group

Since 1984, the Multicenter AIDS Cohort Study (MACS) has utilized four flow cytometry laboratories to measure T-lymphocyte subset levels semiannually in a large cohort of homosexual men. This report summarizes the steps taken in the MACS laboratories to attain comparability of lymphocyte subset determinations across the centers and over time. Identical flow cytometers, monoclonal antibodies, and analytic procedures have been used, and over a period of time, the procedure for sample preparation was also standardized. Interlaboratory proficiency testing utilizing identical specimens analyzed in the four laboratories was performed to evaluate the comparability of the data among the laboratories. Our results verify that such testing can identify technical bias in flow cytometric evaluations performed at different laboratories. Temporal laboratory consistency in flow cytometric measurements was evaluated using data from each site's HIV-seronegative homosexual reference group. Both sequential 95% confidence intervals (mean +/- 2 x SEM) and the within-person standard deviations of the immune measurements were considered. Significant variation in CD3, CD4, and CD8 lymphocyte subset percentages over time in the seronegative reference population was observed. Our observations indicate that the lymphocyte subset values of this seronegative group should be used to adjust those obtained on the seropositive study participants during a particular time period, thereby allowing improved discrimination of the effects of HIV on T cells in infected individuals. The data presented are of use for designing epidemiologic and intervention studies in HIV-1-infected individuals, especially for calculating sample sizes. The methods we have used to assess the quality of data in the MACS have general application to quality control programs in flow cytometry laboratories. In particular, comparison of sequential confidence intervals and within-person standard deviations for lymphocyte subset determinations on control populations are essential to a comprehensive proficiency testing program because they permit assessment of consistency within a laboratory over time.

The prognostic value of cellular and serologic markers in infection with human immunodeficiency virus type 1

We evaluated three cellular and five serologic markers that are affected by infection with the human immunodeficiency virus type 1 (HIV-1) for their ability to predict the progression to clinical acquired immunodeficiency syndrome (AIDS). The cellular markers were the number of CD4+ T cells, the number of CD8+ T cells, and the ratio of CD4+ T cells to CD8+ T cells. The serologic markers were the serum levels of neopterin (a product of stimulated macrophages), beta 2-microglobulin, soluble interleukin-2 receptors, IgA, and HIV p24 antigen. We evaluated the usefulness of these measures as markers of the progression to AIDS prospectively, over four years, in a cohort of 395 HIV-seropositive homosexual men who were initially free of AIDS. CD4+ T cells (expressed as an absolute number, a percentage of lymphocytes, or a ratio of CD4+ to CD8+ T cells) were the best single predictor of the progression to AIDS, but the serum neopterin and beta 2-microglobulin levels each had nearly as much predictive power. The neopterin level appeared to be a slightly better predictor than the beta 2-microglobulin level. The levels of IgA, interleukin-2 receptors, and p24 antigen had less predictive value. A stepwise multivariate analysis indicated that the best predictors, in descending order, were CD4+ T cells (the percentage of lymphocytes or the CD4+: CD8+ ratio), the serum level of neopterin or beta 2-microglobulin, the level of IgA, that of interleukin-2 receptors, and that of p24 antigen. The last three markers had little additional predictive power beyond that of the first two. We conclude that of the eight markers studied, progression to AIDS was predicted most accurately by the level of CD4+ T cells in combination with the serum level of either neopterin or beta 2-microglobulin. At least one of these two serum markers, which reflect immune activation, should be used along with measurement of CD4+ T cells in disease-classification schemes and in the evaluation of responses to therapy.

Development of antibodies to HIV-1 is associated with an increase in circulating CD3+CD4-CD8- lymphocytes

This study investigated whether seroconversion with respect to human immunodeficiency virus, type 1 (HIV-1) was associated with an increase in lymphocytes expressing the CD3+CD4-CD8- phenotype. Proportions and absolute numbers of CD3+, CD4+, and CD8+ lymphocytes were determined prospectively over a 2.5-year period on 4954 homosexual and/or bisexual men participating in the Multicenter AIDS Cohort Study. Of the 4808 men whose serostatus at entry could be verified, 1745 were seropositive (SP) for antibodies to HIV-1 at entry into study, 2795 were uniformly seronegative (SN) for HIV-1 for 30 months, and 268 were seroconverters (SC) with respect to HIV-1 during this period. For each of six semiannual evaluations, proportions and numbers of CD3+CD4-CD8- lymphocytes (calculated as CD3- (CD4 + CD8] were both significantly greater in the SP group than in the SN group (P less than 0.001). Mean CD3+CD4-CD8- levels in the SC group were indistinguishable from those in the SN group before seroconversion, but by 3-9 months after seroconversion the SC group demonstrated absolute numbers of CD3+CD4-CD8- lymphocytes which were significantly increased (P less than 0.001) compared to the SN group using linear regression methods with adjustment for correlation of measurements within an individual over time. An additional significant increase occurred by 21-27 months after seroconversion (P = 0.006). These results are consistent with an association of HIV-1 seroconversion with an increase in circulating T lymphocytes expressing the CD3+CD4-CD8- phenotype (double negative T cells), a decrease in CD3-CD4-CD8+ natural killer cells, or both. An increase in double negative T cells could reflect a host defense mechanism against HIV-1 or effects of HIV-1 on T cell development.

Psychological and immunological associations in men with AIDS pursuing a macrobiotic regimen as an alternative therapy: a pilot study

A group of men with AIDS who chose to follow a macrobiotic regimen as an alternative form of therapy was studied for the possible influence of psychological factors on their clinical progression. In this group, men with Kaposi's sarcoma (KS) had an estimated survival time of 60% at 3 years. Moreover, there was a tendency for lymphocyte number to increase during the first 3 years following diagnosis with KS. A subset of eight of these men with KS and one man with Pneumocystis carinii pneumonia (PCP) agreed to fill out a battery of psychological questionnaires. The results suggest low levels of fatigue, negative affect, and confusion, but high levels of vigor in this subgroup. Additionally, there was significant positive associations of CD4 positive lymphocyte numbers with trait curiosity and hardiness scores and significant negative associations with anxiety and depression. Mitogen responsiveness followed a similar pattern, but only a positive association with curiosity reached significance. Caution has to be used in interpreting such data, especially in view of the size of the sample and the complexity of the cohort. Nonetheless, these findings clearly suggest the need for prospective studies on the influence of psychological factors on the progression of AIDS.

Serial determinations of HIV-1 titers in HIV-infected homosexual men: association of rising titers with CD4 T cell depletion and progression to AIDS

Lymphocyte subset enumerations, antibody titers to specific proteins of human immunodeficiency virus (HIV), and measurement of infectious HIV titers in peripheral blood mononuclear cells were performed on serial blood specimens from 15 HIV-infected homosexual men with chronic lymphadenopathy syndrome (LAS); 6 of these men have subsequently progressed to AIDS (progressors), and 9 have remained clinically stable (nonprogressors). For the earliest samples studied, no test distinguished those who would progress to AIDS from those who have not. The two groups diverged significantly about 1 year before AIDS diagnosis in the progressor group. Virus titers rose in progressors but remained relatively stable in nonprogressors. CD4 T cells and the CD4 T cell subset, 4B4, declined more rapidly in progressors than in nonprogressors. HIV antibody titers tended to decline in progressors, but the differences were significant only for antibody and to the pol-encoded proteins, p51/65, and the gag-encoded polyprotein, p55. Before the onset of clinical AIDS, progressors are distinguished from nonprogressors by markedly different rates of CD4 cell depletion and virus replication, but the elements that control these dynamics remain to be defined.

HIV-serology and lymphocyte subsets in relation to therapy and clinical development in haemophiliacs

389 Swedish patients with haemophilia A, B or von Willebrand's disease were examined for HIV-1 antibodies. T-cell subsets were measured in 260 of them. HIV-1 antibodies were found in 98 of these patients. Of the 199 patients with severe or moderate haemophilia A, 44% were seropositive. They had seroconverted between 1979 and 1983. HIV-1-seropositive patients had significantly decreased numbers of CD4 cells and increased numbers of CD8 cells. The seronegative haemophilia A patients had significantly increased numbers of CD8 cells. The T-cell subsets were followed for a median of 40 months in 73 seropositive patients. All groups of patients, at different clinical stages, showed decreasing numbers of CD4 cells. The most pronounced decrease was seen in the patients who developed AIDS, followed by the group which developed HIV-related signs or symptoms. HIV antigen in serum and antibody pattern in Western blot and ELISA were followed in 89 patients. HIV-1 antigen was present and p24 antibodies were lacking in 11% and 13% of asymptomatic subjects, in 13% and 20% of patients with persistent generalized lymphadenopathy, in 33% and 38% of patients with other HIV-related signs or symptoms and in 5/6 of the AIDS patients, respectively. In conclusion, the decrease of CD4 cells and the presence of HIV antigen and/or absence of p24 antibodies were found to be prognostic markers for HIV disease.