Immune predispositions for cytomegalovirus retinitis in AIDS. The HNRC Group

A Case of Cytomegalovirus Encephalitis in Cluster of Differentiation Four Cell Counts Greater Than 50

Although cytomegalovirus (CMV) encephalitis is a common viral infection, it is rarely reported in immunocompromised patients with cluster of differentiation four (CD4) cell counts greater than 50. Herein, we present a case of CMV encephalitis co-infected with Epstein-Barr virus (EBV) in a human immunodeficiency virus (HIV) patient with a CD4 cell count of 145. In addition, the patient was also infected with syphilis and tuberculosis. This case report will discuss the complications of untangling the differential diagnosis in an immunocompromised host with multiple infections, specifically, how it was difficult to identify the exact etiology of this patient’s encephalopathy. We will address the plausible explanations for this unusual presentation, including CD4 dysfunction, latent and re-infections, and synergism seen with the co-infections in HIV patients.

A Case of Unilateral Coccidioidal Chorioretinitis in a Patient with HIV-Associated Meningoencephalitis

Intraocular coccidioidomycosis is a rare condition, with the most commonly reported presentation being an idiopathic iritis in patients who live in or have traveled thorough endemic areas. A paucity of reports exists describing the chorioretinal manifestations of coccidioidomycosis. Here we report a case of unilateral coccidioidal chorioretinitis and meningoencephalitis in an AIDS patient that led to near complete unilateral loss of vision. A 48-year-old Hispanic female with poorly controlled HIV/AIDS in southern California presented with a three-week history of headache, nausea, vomiting, right eye blurry vision, and a one-day history of subjective fever. Examination of the right eye revealed vitritis and several large chorioretinal lesions scattered throughout the periphery and macula with optic disc pallor. Serum coccidioidomycoses complement fixation (CF) was positive (titers of 1 : 256). Neuroimaging revealed a new area of enhancement in the left anterior frontal lobe consistent with meningoencephalitis. The patient was treated with intravenous fluconazole and intravitreal voriconazole with resolution of systemic symptoms and vitritis but persistence of unilateral, severe chorioretinal scarring and vision loss. In conclusion, in spite of the rarity of intraocular coccidioidomycosis, one must carry a degree of suspicion for this vision- and life-threatening condition as a potential etiology of chorioretinitis in individuals with pertinent risk factors.

Long-Term Follow-up of a Cohort of HIV-Infected Patients Who Discontinued Maintenance Therapy for Cytomegalovirus Retinitis

PURPOSE

To determine the long-term safety of discontinuation of maintenance therapy for cytomegalovirus retinitis (CMVR) and to identify predictors for relapse.

METHOD

This was a prospective cohort study. Patients with treated CMVR who responded to HAART were followed by ophthalmologic assessment, markers for CMV replication (blood and urine cultures, CMV antigenemia, CMV DNA by PCR), and in vitro lymphoproliferative responses to CMV and other antigens after discontinuation of CMVR maintenance therapy.

RESULTS

23 patients were followed a median of 34 (range, 5-61) months. Median CD4 count was 321/mm3 at enrollment and 395/mm3 at last follow-up. HIV RNA was <50 copies/mL in 78% of patients at enrollment and 65% at last follow-up. One CMVR reactivation occurred at 12 months at a CD4 count of 395/mm3 (21%) and HIV RNA <50 copies/mL. Urine cultures were a poor predictive marker for reactivation. Other CMV replication markers had good negative predictive value. 96% of patients had a good lymphoproliferative response to CMV antigen in vitro.

CONCLUSION

Maintenance therapy for CMVR can safely be discontinued in patients who have responded to HAART. Combining our results with the published literature, the risk of reactivation is estimated at 0.016 per person year of follow-up. Markers to predict relapse and the need for re-initiation of maintenance therapy are not yet identified.

Postnatal acquisition of primary rhesus cytomegalovirus infection is associated with prolonged virus shedding and impaired CD4+ T lymphocyte function

BACKGROUND

Although virus-specific CD4(+) T lymphocytes emerge rapidly during primary cytomegalovirus (CMV) infection in humans, they exhibit a state of prolonged functional exhaustion of unknown etiology. To investigate the suitability of rhesus macaques as a model of primary human CMV infection, we examined the virologic and immunologic features of naturally acquired primary CMV infection in rhesus macaques.

METHODS

CMV-specific CD4(+) T lymphocytes and CMV load in blood, saliva, and urine were evaluated in a cohort of simian immunodeficiency virus (SIV)-negative rhesus macaques stratified by age into infant, juvenile, and adult groups.

RESULTS

CMV infection was detected in juvenile and adult monkeys but not in infant monkeys. CMV loads and shedding frequency in urine and saliva were significantly higher in the 2-3-year old juvenile monkeys, compared with the adult monkeys. The increased CMV load in juvenile monkeys was associated with lower polyfunctionality, impaired proliferation, and increased expression of the inhibitory receptor PD-1 in CMV-specific CD4(+) T lymphocytes. The proliferative defect was partially reversible by exogenous PD-1 blockade or addition of interleukin 2.

CONCLUSIONS

Postnatal acquisition of primary CMV infection in rhesus macaques results in prolonged virus excretion and impaired CMV-specific CD4(+) T-lymphocyte function, findings that recapitulate key features of primary CMV infection in humans.

Intensity of the humoral response to cytomegalovirus is associated with the phenotypic and functional status of the immune system

Cytomegalovirus (CMV) infection exerts an enormous effect on human immunity, as it is associated with an immune-impaired response, a variety of chronic diseases, and overall survival in elderly individuals. Levels of anti-CMV antibodies may be associated with the differentiation degree of T cell subsets. Titers are significantly higher in the elderly and positively correlated with specific CD4(+) T cell responses to CMV. In the elderly, antibody titers are associated with the degree of differentiation and the T cell receptor excision circle (TREC) content in CD4(+) T cells, with other features of the immune risk profile, and with a reduced ability to respond to immunization in vivo. Associations may be absent in young subjects because their anti-CMV antibody titers are lower than those of the elderly. However, comparing young and elderly individuals with similar antibody levels reveals differences in their highly differentiated and naïve T cells. These are more marked in individuals with high titers. In parallel with the increase in anti-CMV antibodies, the elderly experience a significant reduction in absolute counts of naïve CD4(+) T cells, which may be a strategy to compensate for the expansion of differentiated cells and to avoid an increase in total T cells. In summary, our results show that titers of anti-CMV antibodies, and not only CMV seropositivity, are related to differentiation status and immunocompetence in the elderly, making this as an important prognostic marker of the status of immune system function.

Functional exhaustion of CD4+ T lymphocytes during primary cytomegalovirus infection

Human CMV establishes lifelong persistence after primary infection. Chronic CMV infection is associated with intermittent viral reactivation inducing high frequencies of CD4+ T lymphocytes with potent antiviral and helper properties. Primary CMV infection is characterized by an intense viral replication lasting for several months. The impact of this prolonged exposure to high Ag loads on the functionality of CD4+ T cells remains incompletely understood. In pregnant women with primary CMV infection, we observed that CMV-specific CD4+ T lymphocytes had a decreased capacity to proliferate and to produce IL-2. A very large proportion of CMV-specific CD4+ T cells had downregulated the expression of CD28, a costimulatory molecule centrally involved in the production of IL-2. Unexpectedly, both CD28+ and CD28+ CD4+ T cells produced low levels of IL-2. This defective production of IL-2 was part of a larger downregulation of cytokine production. Indeed, CMV-specific CD4+ T cells produced lower amounts of IFN-γ and TNF-α and showed lower functional avidity during primary as compared with chronic infection. Increased programmed death-1 expression was observed in CD28+ CMV-specific CD4+ T cells, and programmed death-1 inhibition increased proliferative responses. These results indicate that primary CMV infection is associated with the exhaustion of CMV-specific CD4+ T cells displaying low functional avidity for viral Ags.

CD8dim and NKG2D expression defines related subsets of CD4+ T cells in HIV-infected patients with worse prognostic factors

CD4 T lymphocytes expressing CD8dim (DP: CD4 CD8dim) or NKG2D represent cytotoxic effector populations, which have been involved in viral infections and chronic diseases. The frequency of DP cells was analyzed by flow cytometry in 300 consecutive HIV-infected patients and 50 healthy controls. NKG2D expression and memory/effector markers in CD4 T cells were also studied, in addition to virologic and genetic factors involved in DP T-cell expansion. HIV-infected patients showed a significantly higher frequency of DP cells than controls, mainly in patients with advanced disease. Expansion of DP cells was related to NKG2D appearance in CD4 T cells and was predicted by CD4 CD28null T-cell levels. Cells expressing CD8dim and NKG2D cells are closely related populations with a similar pattern of surface markers, perforin expression, and responses to activation. We also found that these subsets seem to share an ontogenic relationship and TcR oligoclonality. In this way, cytomegalovirus infection and certain HLA alleles, such as DR7, conditioned the expansion of DP cells. Their common ontogenic origin and oligoclonality, possibly due to repeated encounters with the same antigen, could result in a limitation of the repertoire of responder cells and in a worse prognosis of HIV infection.

Immunogenetics of drug-induced skin blistering disorders. Part I: Perspective

The overall immunopathogenesis relevant to a large series of disorders caused by a drug or its associated hyperimmune condition is discussed based upon the examination of the genetics of severe drug-induced bullous skin problems (sporadic idiosyncratic adverse events, including Stevens-Johnson syndrome and toxic epidermal necrolysis). An overarching pharmacogenetic schema is proposed. Immune cognition and early-effector processes are focused upon and a challenging synthesis around systems evolution is explained by a variety of projective analogies. Etiology, human leukocyte antigen-B, immune stability, dysregulation, pharmacomimicry, viruses and an aggressive ethnically differentiated 'karmic' response are discussed.

Immunogenetics of drug-induced skin blistering disorders. Part II: Synthesis

The overall immunopathogenesis relevant to a large series of disorders caused by a drug or its associated hyperimmune condition is discussed based upon examining the genetics of severe drug-induced bullous skin problems (sporadic idiosyncratic adverse events including Stevens–Johnson syndrome and Toxic epidermal necrolysis). New results from an exemplar study on shared precipitating and perpetuating inner causes with other related disease phenotypes including aphtous stomatitis, Behçets, erythema multiforme, Hashimoto’s thyroiditis, pemphigus, periodic fevers, Sweet’s syndrome and drug-induced multisystem hypersensitivity are presented. A call for a collaborative, wider demographic profiling and deeper immunotyping in suggested future work is made.

In vitro cell-mediated immune responses of human immunodeficiency virus-infected and -uninfected individuals to whole cytomegalovirus antigens and their subunits

The aim of this study was to optimize the ability to detect cytomegalovirus (CMV)-specfic cell-mediated immunity (CMI) in human immunodeficiency virus (HIV)-infected individuals by comparing different assays (the lymphocyte proliferation assay [LPA] and assays for gamma interferon [IFN-gamma] and interleukin-2 [IL-2] production) and CMV antigenic preparations. Thresholds discriminating positive from negative CMI results were developed with specimens from 36 CMV-seropositive and 21 CMV-seronegative healthy individuals. The analysis showed that the CMI elicited by any of the four CMV whole lysates tested in this study tended to be more robust and sensitive than the responses to the subunit antigens gB and pp65. LPA and inducible IFN-gamma but not IL-2 were highly sensitive measures of CMV-specific CMI in HIV-infected and -uninfected individuals. The ability to detect CMV-specific LPA or IFN-gamma responses in HIV-infected individuals significantly increased with higher CD4 cell numbers. Nevertheless, the proportion of HIV-infected subjects with CD4 counts of >or=500 cells/mul who had a detectable CMV-specific CMI remained significantly lower than that of healthy adults. The ability to detect CMV-specific CMI in HIV-infected individuals decreased with higher levels of HIV replication, with discriminative thresholds of 10(3) to 10(4) HIV RNA copies/ml of plasma, for LPA or inducible IFN-gamma production elicited by different antigens. The LPA responses obtained with CMV whole lysate and phytohemagglutinin were significantly correlated in HIV-infected subjects but not uninfected controls, indicating a novel characteristic of the CMI defect caused by HIV. The intrasubject variabilities of the CMV-specific CMI were similar in HIV-infected and -uninfected individuals. These data show that LPA and the inducible IFN-gamma production elicited by CMV whole lysates may be used to assess modifications of the immune competency of HIV-infected individuals.

Delayed immune reconstitution after cord blood transplantation is characterized by impaired thymopoiesis and late memory T-cell skewing

Advances in immune assessment, including the development of T-cell receptor excision circle (TREC) assays of thymopoiesis, cytokine-flow cytometry assays of T-cell function, and higher-order phenotyping of T-cell maturation subsets have improved our understanding of T-cell homeostasis. Limited data exist using these methods to characterize immune recovery in adult cord blood (CB) transplant recipients, in whom infection is a leading cause of mortality. We now report the results of a single-center prospective study of T-cell immune recovery after cord blood transplantation (CBT) in a predominantly adult population. Our primary findings include the following: (1) Prolonged T lymphopenia and compensatory expansion of B and natural killer (NK) cells was evident; (2) CB transplant recipients had impaired functional recovery, although we did observe posttransplantation de novo T-cell responses to cytomegalovirus (CMV) in a subset of patients; (3) Thymopoietic failure characterized post-CBT immune reconstitution, in marked contrast to results in other transplant recipients; and (4) Thymopoietic failure was associated with late memory T-cell skewing. Our data suggest that efforts to improve outcomes in adult CB transplant recipients should be aimed at optimizing T-cell immune recovery. Strategies that improve the engraftment of lymphoid precursors, protect the thymus during pretransplant conditioning, and/or augment the recovery of thymopoiesis may improve outcomes after CBT.

Vesicovaginal Fistula Associated with Cytomegalovirus Infection in an HIV-Infected Patient

BACKGROUND

Cytomegalovirus (CMV) can cause multisystem disease in human immunodeficiency virus (HIV)-infected patients. An association with a vesicovaginal fistula has not previously been reported.

CASE

An HIV-infected African-American female presented with back pain, swelling and paralysis of her lower extremities and continuous leakage of urine. Fundoscopic examination was typical of CMV retinitis. Doppler and CT studies showed bilateral deep vein thrombosis and bilateral pulmonary emboli, respectively. Anticoagulant therapy was started, and a Greenfield filter was placed. An examination under anesthesia and cystoscopy showed extensive vulvar and rectal condylomata, a large, necrotic, anterior vaginal mass, and a large vesicovaginal fistula. All necrotic tissue was resected and the biopsies taken identified CMV cytopathic effect.

CONCLUSION

Vesicovaginal fistula in an immunocompromised individual may be a local manifestation of systemic CMV disease.

Human Immunosenescence: Does It Have an Infectious Component?

The rate of acceleration of the frequency of death due to cardiovascular disease or cancer increases with age from middle age up to around 75-80 years, plateauing thereafter. Mortality due to infectious disease, however, does not plateau, but continues to accelerate indefinitely. The elderly are particularly susceptible to novel infectious agents such as SARS, as well as to previously encountered pathogens. Why is this? The elderly commonly possess oligoclonal expansions of T cells, especially of CD8 cells, which, surprisingly, are associated with cytomegalovirus (CMV) seropositivity. This in turn is associated with many of the same phenotypic and functional alterations to T cell immunity that have been suggested as biomarkers of immune system aging. We suggest that, in fact, CMV, not age per se, is the prime driving force behind many or most of the oligoclonal expansions and altered phenotypes and functions of CD8 cells in the elderly. Thus, the manner in which CMV and the host immune system interact (over which period? on which genetic background? with which co-infections?) is critical in determining the "age" of adaptive immunity and hence human longevity. In this respect, immunosenescence is infectious.

Cytokine profile in response to Cytomegalovirus associated with immune recovery syndrome after highly active antiretroviral therapy

BACKGROUND

Several changes have occurred in the presentation and course of cytomegalovirus (CMV) retinitis in patients with AIDS since the introduction of HAART (highly active antiretroviral therapy). In some individuals who take HAART, retinitis is kept under control even after the discontinuation of anti-CMV therapy. However, many of these patients develop intraocular inflammation. Uveitis, cataract, vitreitis, cystoid macular edema, epiretinal membrane, and disc edema may occur in patients with immune recovery syndrome (IRS).

METHODS

We evaluated the CMV-specific immune response in 55 patients by assessing CMV-specific lymphocyte proliferation, cytotoxicity, and cytokine production and correlated it with the clinical outcome.

RESULTS

Our data suggest that control of CMV retinitis is associated with acquisition of cytotoxic and lymphoproliferative responses to CMV. In addition, the upsurge of macular and disc edema seems associated with the production of interleukin-4 and tumor necrosis factor-alpha, whereas vitreitis is associated with the production of interleukin-2 and interferon-gamma.

INTERPRETATION

The type of T-cell response that develops after HAART may determine the side effects of immune recovery and these effects are predictable based on the lymphokine profile produced by CMV-specific cells.

Laboratory-based risk factors for cytomegalovirus retinitis

BACKGROUND

Very few studies have investigated risk factors for cytomegalovirus (CMV) retinitis. Identifying these risk factors will have many benefits, including helping establish screening regimens, examination frequency regimens, and targeted prophylaxis with oral therapy with valganciclovir or other anti-CMV agents. The purpose of this study was to determine the laboratory-based risk factors for CMV retinitis in patients with AIDS.

METHODS

We conducted a case-control study involving 120 patients in whom CMV retinitis had been diagnosed in 1990-99 and 159 patients without CMV retinitis from the same period. The sampling was from a primary study base in eastern Ontario and western Quebec of patients with AIDS and CD4 counts less than 50 cells/microL at the time of diagnosis of retinitis in the case subjects or an analogous date for the control subjects. There were two components to the study. In the first component (n = 279) we examined standard-of-care laboratory tests (hematologic and nutrition variables) done during the study period. In the second component (n = 57), which was a subset of the first, we examined laboratory tests (HLA type, qualitative and quantitative CMV polymerase chain reaction [PCR] and HIV load) on stored blood samples from the eastern Ontario site. Multivariate logistic regression was used to model the data and control for confounding. We developed a systematic model-building strategy, from assumption testing to model building to model checking.

RESULTS

A low hemoglobin concentration was a statistically significant predictor of CMV retinitis (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.94-0.98). Both qualitative CMV PCR (OR 21.71, 95% CI 1.80-261.67) and quantitative CMV PCR (OR 33.03,95% CI 2.32-469.39) were strong predictors of CMV retinitis. Among the 80 HLA types tested, HLA-Bw4 (OR 11.68, 95% CI 1.29-105.82) and HLA-DRB115 (OR 9.34, 95% CI 1.14-76.41) were significant predictors of CMV retinitis, whereas HLA-Cw7 was protective against CMV retinitis (OR 0.09, 95% CI 0.01-0.67).

INTERPRETATION

We have identified laboratory variables that elevate (or decrease) the risk of CMV retinitis. These findings may be useful to clinicians and health policy experts in developing rational guidelines for screening, examination frequency and targeted prophylaxis for patients with AIDS.

CMV antigen-specific CD4+ and CD8+ T cell IFNgamma expression and proliferation responses in healthy CMV-seropositive individuals

CMV-specific CD4+ and CD8+ T cell IFNgamma expression and proliferation were measured in healthy volunteers by flow cytometry after CMV lysate or CMV pp65 or IE peptide pool stimulation. Cutoff values were set to maximize specificity (i.e., no false positive CMV-seronegatives). Sensitivity (defined as a positive response in CMV-seropositives to at least one of the 3 antigen preparations used) was 100% for CMV-specific CD4+ and CD8+ T cell IFN expression and CD4+ T cell proliferation and 95.4% for CMV-specific CD8+ T cell proliferation. All 22 CMV-seropositive individuals had positive responses by at least three of these four measurements. These findings support the concept that a multiplicity of antigen-specific functional immune responses and persistence of robust virus-specific CD4+T cells are important components of protective immunity in this chronic viral infection.

Cytomegalovirus infection in the era of HAART: fewer reactivations and more immunity

The incidence of cytomegalovirus (CMV) disease, once the most common and highly feared viral complication of AIDS, has dramatically decreased with the advent of highly active antiretroviral therapy (HAART). HAART-associated changes in the epidemiology of CMV disease resulted from the increase in CMV-specific immune responses coupled with the decrease in CMV reactivation. However, CMV disease continues to afflict HIV-infected patients on HAART when CD4+ cell counts fail to rise above 100 cells/mm(3) and when reconstitution of normal CMV-specific immune responses does not occur. The latter scenario may lead to recurrent or de novo CMV end-organ disease, or to the recently described CMV immune recovery vitritis. HAART-associated immune reconstitution offers unique opportunities to investigate the virological and immunological correlates of protection against CMV disease. Although the full extent of CMV-specific immune reconstitution has not been defined thus far, CMV-specific interferon-gamma production has been shown to be significantly associated with protection against CMV reactivation and recurrent disease.

Cellular immune response of fetuses to cytomegalovirus

Primary infection with cytomegalovirus (CMV) in immunocompetent hosts is accompanied with activation and differentiation of naive CD8(+) T cells to effector/memory cells secreting interferon-gamma (IFN-gamma). Alteration of these responses during the perinatal period is suggested by a higher rate of CMV diseases in congenital infection. For addressing this issue, immunologic investigations were performed in 15 fetuses (22-36 wk of gestation) with documented congenital CMV infection. Results show that cellular immune responses can be detected as soon as the 22nd week of gestation (the youngest fetus analyzed). Compared with age-matched control subjects, infected fetuses evidence a dramatic increase in the percentages of activated and terminally differentiated CD8 T cells. Indeed, median percentages (interquartile range) of HLA-DR(+) and of CD28(-)CD8(+) T cells were 24% (19-34) and 38% (24-52), respectively in infected fetuses versus 3% (0-4) for each subset in control subjects. In addition, the percentages of T cells secreting IFN-gamma after in vitro stimulation with phorbol myristate acetate and ionomycin was significantly higher in infected fetuses [10% (5-25)] than in healthy fetuses [0.8% (0.6-1.2)] with IFN-gamma being mostly secreted by CD8(+) T cells and to a lesser extend by CD4(+) T cells. These cellular immune responses have clear similarities with responses previously reported in adults. Cellular immunity to CMV, however, might not be fully functional in fetuses. Indeed, the number of T cells capable of secreting IFN-gamma is strikingly lower after in vitro stimulation with the CMV-specific antigen than after in vitro stimulation with phorbol myristate acetate/ionomycin that bypasses signaling through the T-cell receptor.

Frequency of HLA class 1 and 2 alleles in Brazilian patients with AIDS and cytomegalovirus retinitis

PURPOSE

To evaluate the human leucocyte antigen (HLA) class 1 (HLA-A and HLA-B) and HLA class 2 (HLA-DRB1 and HLA-DQB1) allele profiles in the susceptibility to cytomegalovirus retinitis (CMV-R) in patients with AIDS.

METHODS

Cytomegalovirus retinitis was clinically diagnosed by indirect binocular ophthalmoscopy. Human leucocyte antigens class 1 were typed using a complement-dependent microlymphocytotoxicity assay, and HLA class 2 alleles were identified using amplified DNA hybridized to sequence-specific oligonucleotide primers.

RESULTS

The frequencies of HLA class 1 antigens and HLA class 2 alleles observed in patients and controls were similar; however, HLA-A31 antigen was over-represented in patients with AIDS, independent of the presence of CMV-R.

CONCLUSION

There was no association between HLA molecules/alleles and CMV-R in Brazilian patients with AIDS. However, the results support the role of the HLA system in the susceptibility to developing AIDS.

Immune recovery uveitis in AIDS patients with cytomegalovirus retinitis treated with highly active antiretroviral therapy in Venezuela

PURPOSE

To determine the characteristics of immune recovery uveitis (IRU) in acquired immunodeficiency syndrome (AIDS) patients with inactive cytomegalovirus (CMV) retinitis who responded to highly active antiretroviral therapy (HAART) in a Venezuelan population.

METHODS

We examined 34 patients (50 eyes) with AIDS (HAART responders) and healed CMV retinitis. Patients were observed for a median of 19.3 months following an increase in the CD4 cell count. Ten eyes were treated with sub-Tenon space corticosteroid injections. An age-matched control group of patients with healed CMV retinitis who did not have IRU (30 eyes of 20 patients) was included to compare CMV surface area and complications.

RESULTS

We found that 12 (37.5%) of 32 HAART responders developed IRU (18 eyes). The clinical findings of these 18 eyes with IRU are presented. The clinical spectrum of inflammation included vitritis, macular edema, epiretinal membranes, anterior uveitis, macular hole, retinal detachment with proliferative vitreoretinopathy, and cataract. Eyes with IRU had a mean CMV surface area of 31.7%. However, eyes without IRU (control group) had a mean CMV surface area of 35% (P = 0.41). Periocular treatment resulted in vision improvement (in 90% of eyes) without reactivation of retinitis.

CONCLUSIONS

Symptomatic IRU developed in a significant number of patients with CMV retinitis following successful HAART in a Venezuelan population. CMV surface area does not seem to be a risk factor for the development of IRU. Eyes with IRU respond favorably to antiinflammatory therapy without reactivation of retinitis.

Application of a 5-bromo-2′-deoxyuridine ELISA for measuring the lymphoproliferative response to human cytomegalovirus in HIV-1-infected patients

Assessment of the lymphoproliferative response to human cytomegalovirus (HCMV) may help to identify human immunodeficiency virus (HIV)-1-infected patients at high risk of developing HCMV end-organ disease. The tritiated thymidine ([3H]-TdR)-incorporation assay is the gold standard for measuring lymphoproliferative responses, though it is unsuitable as a routine laboratory procedure. An alternative non-radioactive technique, a 5-bromo-2'-deoxyuridine (BrdU) enzyme-linked immunosorbent assay, was applied for measuring T-cell proliferation in response to HCMV. Stimulation of either 1 x 10(5) or 5 x 10(4) peripheral blood mononuclear cells (PBMCs)/well with 10 PFU/well (before inactivation) of inactivated HCMV (AD169 strain) virions during 5 days, followed by an 18 h period of pulsing with BrdU (10 microM) proved to be the optimal laboratory conditions. The assay is simple, economical and feasible for monitoring the lymphoproliferative response to HCMV in HIV-1-infected patients.

Paradoxical activity of CMV retinitis in patients receiving highly active antiretroviral therapy

PURPOSE

To report two types of atypical behaviors of cytomegalovirus (CMV) retinitis in the highly active antiretroviral therapy (HAART) era, including active CMV retinitis in the presence of persistently high CD4 cell counts during HAART and CMV retinitis that has not reactivated despite persistently low CD4 cell counts.

METHODS

Prospective, longitudinal, observational study of a cohort of 116 patients with acquired immunodeficiency syndrome who had a history of CMV retinitis during the HAART era.

RESULTS

Sixty (52%) of the 116 patients with acquired immunodeficiency syndrome and CMV retinitis were HAART responders. Subsequently, HAART failed for 9 of the 60 patients with low CD4 cell counts. Of these 9 patients, 5 developed reactivation of CMV retinitis, and 4 remained free of CMV retinitis despite CD4 cell counts of <50/microL and lack of anti-CMV therapy. Paradoxically, there was a patient with a documented median CD4 cell count of 204/microL for 19 months who had newly diagnosed active CMV retinitis.

CONCLUSION

In the HAART era, CMV retinitis may remain quiescent despite extremely low CD4 cell counts, and rarely, CMV retinitis may become active in the setting of persistently high CD4 cell counts in a subset of HAART responders.

Declining levels of rescued lymphoproliferative response to human cytomegalovirus (HCMV) in AIDS patients with or without HCMV disease following long-term HAART

OBJECTIVE

To investigate the lymphoproliferative response (LPR) to human cytomegalovirus (HCMV) in two groups of AIDS patients undergoing long-term highly active antiretroviral therapy (HAART): group 1 ( n = 22) with nadir CD4(+) cell count <50/microl and no HCMV disease; group 2 ( n = 16) with <50/microl CD4(+) T-cell count and HCMV disease. All patients had previously undergone antiretroviral monotherapy or dual therapy before initiating HAART.

STUDY DESIGN AND METHODS

The two groups of patients were tested prospectively for CD4(+) T cell count, HIV RNA load, HCMV viremia, and LPR to HCMV at baseline, and then after 3 and 4 years of HAART. A control group of 13 recently diagnosed treatment-naive AIDS patients with CD4(+) T-cell counts <100/microl was also investigated.

RESULTS

No LPR to HCMV was found in any of the treatment-naive patients nor in any patient of the two groups examined at baseline, when HCMV viremia was 13.6% in the patient group without disease and 87.5% in the group with disease ( p <.0001). After 3 years of HAART, the frequency of patients who recovered an LPR to HCMV was not significantly different (81.8% in the group without HCMV disease, and 68.7% in the group with HCMV disease), whereas, compared with baseline, the HIV load decreased and the CD4(+) T-cell count increased significantly and to a comparable extent in the two groups of patients. In addition, the frequency of patients with HCMV viremia, although reduced, became comparable in both groups. After 4 years of HAART, the frequency of responders to HCMV without and with HCMV disease dropped to comparable levels (50.0 vs. 56.3%, respectively) in association with high median CD4(+) T-cell counts and low median HIV RNA plasma levels. In parallel, the frequency of patients with HCMV viremia did not change significantly. In addition, after between 3 and 4 years of HAART, although the frequency of stable responders and nonresponders remained unchanged (50%) in both groups, most of the remaining patients showed declining levels of responsiveness to HCMV. Although some patients from both groups were found to have CD4(+) T-cell counts >150/microl in the absence of LPR to HCMV, thus suggesting dissociation of specific and nonspecific immune reconstitution, a significant correlation was found between CD4(+) T-cell count and LPR to HCMV (r = 0.44; p <.001). From a clinical standpoint, anti-HCMV therapy could be safely discontinued in 8 patients with HCMV retinitis showing CD4(+) T-cell counts >150/microl, recovery of HCMV LPR, and no HCMV viremia.

CONCLUSIONS

Declining levels of the previously recovered LPR to HCMV are often observed after long-term HAART. However, because the role of LPR in the evolution of HCMV infection and disease during HAART remains to be defined, the clinical impact of the declining LPR to HCMV must still be clarified in long-term prospective studies.

Comparative analysis of human cytomegalovirus-specific CD4(+) T-cell frequency and lymphoproliferative response in human immunodeficiency virus-positive patients

Evaluation of human cytomegalovirus (HCMV)-specific T-helper immunity could contribute in optimizing anti-HCMV therapy in human immunodeficiency virus (HIV)-infected patients. Testin the lymphoproliferative response (LPR) is the standard technique used to evaluate T-helper response, but its use in the routine diagnostic laboratory setting can be problematic. The most promising new alternative technique is the determination of HCMV-specific CD4(+) T-cell frequency by flow cytometry detection of intracellular cytokine production after short-term antigen-specific activation of peripheral blood mononuclear cells. HCMV-specific LPR and CD4(+) T-cell frequency were compared in a group of 78 blood samples from 65 HIV-infected patients. The results showed concordance in 80.7% of samples. In addition, comparative analysis of sequential blood samples from 13 HIV-infected patients showed that while in about half of patients the T-helper HCMV-specific immune response remained stable during highly active antiretroviral therapy (HAART), in the other half declining levels of the HCMV-specific CD4(+)-mediated immune response were determined by either one or both assays. In conclusion, our data suggest that the determination of HCMV-specific CD4(+) T-cell frequency can be considered a valuable alternative to the LPR test for the detection of HCMV-specific T-helper response in HIV-infected patients. It could facilitate wider screening of anti-HCMV T-helper activity in HIV-infected patients, with potential benefits for clinicians in deciding strategies of discontinuation or maintenance of anti-HCMV therapy.

Immune dysfunction and immune restoration disease in HIV patients given highly active antiretroviral therapy

BACKGROUND

Some immune defects caused by HIV infection resolve following treatment with highly active antiretroviral therapy (HAART), but residual immune dysfunction may cause disease. Problems with the regulation of the restored immune system in the first six months of treatment can lead to atypical presentations of mycobacterial, cytomegalovirus (CMV), hepatitis B virus or hepatitis C virus (HCV) disease. We defined these conditions as immune restoration diseases (IRD) and showed that they occur in 30-40% of individuals who begin HAART from low CD4 T cell counts.

OBJECTIVES

Analysis of immune dysregulation in patients who have responded to HAART.

STUDY DESIGN

Patients with successful immune reconstitution following HAART were selected from a database containing details of all patients managed at Royal Perth Hospital (Western Australia) on the basis a CD4 T cell count <100/microl before HAART and an increase of >4-fold or to >200 CD4 T cells/microl.

RESULTS

Patients who had experienced an IRD demonstrated increased levels of bioavailable IL-6 and increased expression of CCR5 and CCR3 on monocytes and granulocytes, but numbers of gammadeltaT-cells were similar to patients with similar CD4 T cell counts without an IRD. Carriage of HLA-A2, -B44 was associated with a history of CMV retinitis and/or encephalomyelitis as an IRD, but not with IRD initiated by Mycobacterium sp., cutaneous varicella zoster or herpes simplex infections or HCV. We also identified a patient with Graves' thyrotoxicosis and pronounced lymphadenopathy after HAART, and demonstrated that thyroid stimulating hormone receptor antibody production was associated with an increase in serum soluble CD30, suggesting acquired immune dysregulation.

CONCLUSIONS

IRD are associated with persistent immune activation, where differences in genetic profiles suggest that distinct pathological mechanisms are responsible for retinitis/encephalomyelitis IRD. Further studies are important as dysregulated T-cell responses may cause disease later in the course of immune reconstitution.

Discordant cellular and humoral immune responses to cytomegalovirus infection in healthy blood donors: existence of a Th1-type dominant response

Previous studies have documented discordant cellular and humoral immune responses to subjects exposed to HIV-1, and that the nature of such responses may determine susceptibility and resistance to disease. We determined whether there is a spectrum of cellular versus humoral immunodominant responses to cytomegalovirus (CMV) infection. Blood samples from 50 healthy blood donors were tested for anti-CMV IgG antibodies and for proliferative responses of peripheral blood mononuclear cells (PBMC) to CMV antigens. Four patterns of immune responses to CMV were found: no detectable response (30%, Ab(-)/Tc(-)), anti-CMV IgG only (28%, Ab(+)/Tc(-)), both anti-CMV IgG and T lymphocyte proliferation to CMV antigens (18%, Ab(+)/Tc(+)), and, interestingly, T lymphocyte proliferation to CMV only (24%, Ab(-)/Tc(+)). To determine whether these immunodominant phenotypes correlate with the ability of PBMC to secrete IL-2 and IFN-gamma in response to CMV antigens, we found that a greater percentage of individuals with a T cell proliferative response to CMV antigens (Ab(-)/Tc(+) and Ab(+)/Tc(+)) responded with increased IL-2 (P = 0.001) and IFN-gamma levels (P = 0.002), compared to those without a proliferative response (Ab(-)/Tc(-) and Ab(+)/Tc(-)). Our data therefore demonstrate that different individuals exhibit different immunodominant patterns of response to CMV. In particular, some individuals who are exposed to CMV fail to develop an antibody response but do develop cellular immunity. Whether these different patterns predict susceptibility or resistance to CMV-induced disease remains to be determined.

MHC haplotypes affect the expression of opportunistic infections in HIV patients

This study explores whether MHC genes affect manifestations of opportunistic infections in HIV patients not treated with highly active antiretroviral therapy (HAART) and immunopathologic responses to pre-existing infections in patients who achieved immune reconstitution following HAART (i.e., "immune restoration diseases" or IRD). HLA-B27 and B17 were relatively rare in all HIV patients, but no HLA-B alleles significantly affected cytomegalovirus (CMV) or Mycobacterium avium complex (MAC) disease in patients who had not received HAART. However coexpression of alleles previously defined as the 44.1 ancestral haplotype (HLA-A2, -B44, and -DR4) was more common in the MAC and CMV patients. After HAART, HLA-B44 and (HLA-A2, -B44, -DR4) were found in 66% and 33%, respectively, of patients who experienced an IRD manifested as CMV retinitis and/or encephalomyelitis. This was confirmed by examination of microsatellite alleles, where the C1_2_5 locus in the class I region was most concordant with the 44.1 haplotype in the patients. HLA-B44 was not associated with IRD initiated by Mycobacterium sp, cutaneous VZV or HSV, or HCV infections, suggesting distinct pathologic mechanisms are responsible. CMV retinitis/encephalomyelitis IRD patients had marginally lower pretreatment CD4 T-cell counts, but indices of immune reconstitution were similar in all groups and independent of HLA-B44.

Direct measurement of CD4+ and CD8+ T-cell responses to CMV in HIV-1-infected subjects

Data from murine models of chronic viral infection suggest that CD4+ T-cell responses to viral pathogens are important in sustaining the number and/or function of CD8+ cytotoxic T-cell (CTL) effectors. In this study, we used cytokine flow cytometry (CFC), staining with HLA-A*0201-peptide tetramers, and peptide stimulation with epitopic peptides to study functional CD4+ and CD8+ T-cell responses to cytomegalovirus (CMV) in human subjects coinfected with CMV and the human immunodeficiency virus, type 1 (HIV-1). We show that strong CD4+ and CD8+ T-cell responses to CMV antigens are sustained over time in HIV-1-infected individuals. Those who maintain a strong CD4+ T-cell response to CMV are also likely to maintain higher frequencies of CD8+ T cells capable of binding to HLA-A*0201-CMV pp65 (A2-pp65) tetramers as well as responses to pp65 peptide stimulation with effector cytokine production. These data support the hypothesis that declines in frequencies of CD4+ T-cell responses to CMV are associated with an inability to sustain high levels of CMV-specific CD8+ T-cell responses in HIV-1-infected subjects. These declines may precede the onset of CMV-associated end organ disease.

Host response to cytomegalovirus infection as a determinant of susceptibility to coronary artery disease: sex-based differences in inflammation and type of immune response

BACKGROUND

Positive and negative associations between cytomegalovirus (CMV) infection and coronary artery disease (CAD) have been reported. We postulated that the susceptibility to CMV-induced CAD might relate to patterns of inflammatory and immune responses to CMV infection and that sex might have an effect on these responses.

METHODS AND RESULTS

In 151 men and 87 women being evaluated for CAD, blood samples were tested for humoral (Ab+) and cellular (Tc+) responses to CMV and for C-reactive protein (CRP). In men, an elevated CRP level was a significant determinant of CAD even after adjustment for CAD risk factors (OR, 3.1; 95% CI, 1.21 to 7. 97). CMV seropositivity was associated with elevated CRP levels on multivariate analysis (P:=0.006). In contrast, in women, CMV seropositivity was independently predictive of CAD (OR, 41.8; 95% CI, 4.12 to 423.74). CRP level in women with CAD was >25% higher than those without CAD, but the difference did not reach statistical significance. Importantly, compared with CMV Ab-/Tc- women, CAD prevalence was higher in Ab+/Tc- and Ab+/Tc+ (13% versus 68% and 64%, both P:<0.005) but not in Ab-/Tc+ women (25%). There were no differences in age, smoking, diabetes, hypertension, and hypercholesterolemia among women with different types of immune responses to CMV infection.

CONCLUSIONS

The mechanisms by which CMV predisposes to CAD in men and women may be different. In men, CMV appears to contribute to CAD risk, insofar as it predisposes to inflammation. In women, other mechanisms, possibly related to the type of immune response generated by the host, appear to be responsible for the proatherogenic effects of CMV.

Progressive reduction of CMV-specific CD4+ T cells in HIV-1 infected individuals during antiretroviral therapy

Visualization of antigen-specific T cells has become an important tool in studying immune responses. The aim of this study was to analyze CMV-specific CD4+ T cells in healthy and HIV-infected individuals. Peripheral blood mononuclear cells (PBMC) were examined for antigen-induced intracellular cytokine responses. We found significant numbers of CMV-specific CD4+ T cells detectable in most CMV-IgG+ HIV-1 infected individuals, whereas CMV-specific CD4+ T cells could not be demonstrated in CMV-IgG- patients. Median frequency of CMV-specific CD4+ T cells were lower in HIV-infected subjects who had been treated with highly active antiretroviral therapy (HAART) for more than 1 year than in untreated HIV-infected individuals. In patients under therapy for less than 1 year median CMV-specific CD4+ T cell responder frequency was higher than in subjects treated for more than 1 year but lower than in untreated subjects. HIV suppression with HAART might lead to a progressive reduction of CMV-specific CD4+ T cells indicating an efficient elimination of an opportunistic pathogen.

CMV retinitis recurs after stopping treatment in virological and immunological failures of potent antiretroviral therapy

OBJECTIVES

To determine predictors of clinical relapse of cytomegalovirus (CMV) end-organ disease in a cohort of 17 HIV-infected patients with healed and treated CMV retinitis (CMVR) who responded to HAART with an increase in CD4 cell counts to above 70 cells/mm3 and discontinued CMV maintenance therapy (MT).

DESIGN

Seventeen patients were monitored for reactivation of retinitis. The CD4 cell counts, HIV RNA and peripheral blood mononuclear cell (PBMC) lymphoproliferative assays to CMV at 3 month intervals were compared between patients with and without reactivation of CMVR. Positive lymphoproliferative responses were defined as a stimulation index of 3 or greater.

RESULTS

Five out of 17 (29%) patients experienced a recurrence of CMVR a mean of 14.5 months after stopping CMV MT and between 8 days and 10 months after CD4 cell counts fell below 50 cells/mm3. Median CD4 cell counts and plasma HIV RNA at reactivation were 37 cells/mm3 and 5.3 log10 copies/ml. Three patients recurred at a previously active site of the retina, one had contralateral CMVR, and one a recurrence of retinitis and pancreatitis simultaneously. Mean lymphoproliferative responses to CMV were 2.4 in patients with reactivation versus 21.0 stimulation index (SI) in patients without reactivation (P= 0.01). A model incorporating four variables (CD4 cell counts and HIV RNA at maintenance discontinuation, highest CD4 cell count, nadir HIV RNA and median lymphoproliferative responses) identified correctly 88% of patients with and without reactivation.

CONCLUSION

CMV disease recurs after virological and immunological failure of HAART if CD4 cell counts drop below 50. In this situation, anti-CMV agents should be resumed before clinical reactivation ensues, because of the risk of contralateral retinal involvement and systemic disease.

Lymphocyte proliferation assays may underestimate antigen responsiveness in human immunodeficiency virus infection

The objective of this study was to examine the relationships among lymphocyte proliferation, interferon-gamma (IFN-gamma) production, and apoptosis in peripheral blood mononuclear cells (PBMC) of HIV-1-infected patients and controls. PBMC were prepared from 19 HIV-1-infected patients and 16 healthy controls. Using tetanus toxoid (TT) as a recall antigen, we assessed lymphocyte proliferation using [(3)H]thymidine incorporation after 2, 4, 6, and 7 days' culture and IFN-gamma production in 48-h culture supernatants by ELISA. Apoptosis was measured using TdT-mediated dUTP nick-end labeling. Median stimulation indices (SIs) in HIV-1-infected patients were 2.8 and 3.7 as opposed to 24.9 and 25.1 in healthy controls after 6 and 7 days' culture, respectively (P < 0. 001). Among the controls, peak proliferation was seen after 7 days in culture whereas in patients, SIs peaked at 4 days and fell progressively by days 6 and 7. At 2 and 4 days of stimulation with tetanus, patients' T cells showed increased apoptosis (19 and 25%) vs 12 and 15% apoptosis seen in controls' cells, P < 0.05. Interferon-gamma in 48-h supernatants of TT-stimulated PBMC was comparable among patients and controls. Whereas in our system, 6 and 7 day assays of lymphocyte proliferation provide increasing responses to TT among healthy controls, these durations of culture may underestimate antigen responsiveness in HIV-1 infection. Cell death due to apoptosis may account for this phenomenon. Whether shorter term or longer term assays of lymphocyte responsiveness more accurately reflect in vivo immune competence is unknown. Nonetheless, shorter duration assays may provide a more realistic estimate of the frequency of antigen-reactive cells in persons with HIV-1 infection.

Novel potential agents for human cytomegalovirus infection: synthesis and antiviral activity evaluation of benzothiadiazine dioxide acyclonucleosides

The first acyclonucleosides based on the benzothiadiazine dioxide system were synthesized following the silylation procedure. Several acyclic moieties, including acetoxyethoxymethyl, benzyloxymethyl, and propargyloxymethyl groups, were introduced. Two synthetic strategies were designed to selectively obtain the N-1 or N-3 derivatives. Lipase-mediated deacylation was used for the deprotection of the acyclonucleosides. Some of the benzothiadiazine dioxide acyclonucleosides, in particular 16, proved active against human cytomegalovirus (CMV) at concentrations slightly higher than that found for ganciclovir [50% inhibitory concentration (IC50) = 3. 5-3.7 micrograms/mL, cytotoxicity (CC50) >/= 40 micrograms/mL, MCC = 20 micrograms/mL]. Additionally, compound 16 inhibited the replication of human immunodeficiency virus type 1 (HIV-1) and HIV-2 in CEM cells at concentrations that were 5-fold lower than its cytotoxic concentration.

Telemedicine diagnosis of eye disorders by direct ophthalmoscopy. A pilot study

OBJECTIVE

To report a pilot study of telemedical direct ophthalmoscopy in the diagnosis of acquired immune deficiency syndrome (AIDS)-related retinopathy in a human immunodeficiency virus (HIV)-positive population and in the diagnosis of glaucoma, cataract, and retinopathy in a diabetic population.

DESIGN

Prospective comparative case series.

PARTICIPANTS

Seventeen HIV-positive and 20 diabetic patients.

METHODS

A direct ophthalmoscope custom-fitted with a digital microcamera capable of transmitting images from any of 61 sites within the Georgia Statewide Telemedicine Program was used by a nonophthalmologist to examine 34 eyes of 17 HIV-positive patients and 39 eyes of 20 patients with diabetes. Fundus images were transmitted in real-time to a reviewing ophthalmologist. An in-person, comprehensive examination including indirect ophthalmoscopy, was performed by a second ophthalmologist. Telemedical examination was compared to the in-person comprehensive examination.

RESULTS

For the HIV study, 21 eyes did not show HIV retinopathy (noninfectious retinopathy with cotton-wool spots) by in-person examination. Telemedical examination correctly identified 20 of these eyes as disease-free (specificity = 95%). HIV retinopathy was present in 12 of the 34 eyes by in-person evaluation with telemedical examination correctly diagnosing 10 of these eyes (sensitivity = 83%). One eye with dense cataract and retinal detachment was unable to be evaluated ophthalmoscopically by either in-person or telemedical examination. Telemedical and in-person assessments for HIV retinopathy were identical in 100% of eyes without cataract. Disagreement in diagnosis between telemedical and in-person examination was associated with cataract (P < 0.0007). For the diabetes study, because of an inadequate image, telemedical examination was unable to classify 46% and 36% of eyes for glaucoma and diabetic retinopathy, respectively. Inability to make a telemedical determination for glaucoma (P < 0.011), nonproliferative (P < 0.064) and proliferative (P < 0.064) diabetic retinopathy was associated with cataract. Of the eyes that were able to be assessed by telemedical examination for diabetic retinopathy (n = 25), glaucoma (n = 21), and cataract (n = 39), the accuracy was poor (sensitivity = 29%, 50%, and 41%, respectively). Telemedical examination for diabetic retinopathy and glaucoma was more likely to agree with in-person examination in eyes without cataract as compared to eyes with cataract (not statistically significant).

CONCLUSION

Telemedical direct ophthalmoscopic, real-time fundus imaging may provide a valuable means for providing ophthalmic consultation to the primary care physician in younger patients without lens or media opacity, but is inadequate for eyes with any degree of lens or media opacity.

Cytomegalovirus retinitis, human immunodeficiency virus antibody positivity and normal T helper cell numbers

We describe a 46-year-old man in whom retinitis was diagnosed as his initial HIV and AIDS defining illness. A diagnosis of CMV infection was made based on the clinical appearance of the fundus and confirmed by DNA polymerase chain reaction (PCR) on his vitreous biopsy. His CD4+ T lymphocyte count at the time was 580 x 10(6)/l (16%) with a CD4:CD8 ration of 0.28. He had a splenectomy following trauma more than 20 years earlier. He responded very well to intravenous and oral ganciclovir and remains recurrence-free almost 2 years later. This case and others highlight two issues: (i) CMV retinitis in HIV positive is not confined to those with very low CD4+ T lymphocyte counts; (ii) previous splenectomy may have an impact on CD4+ cell numbers and function.

Restoration of cytomegalovirus-specific CD4+ T-lymphocyte responses after ganciclovir and highly active antiretroviral therapy in individuals infected with HIV-1

Recent studies of subjects infected with human immunodeficiency virus (HIV-1) have produced conflicting results about the extent of reconstitution possible in the CD4+ lymphocyte repertoire after highly active antiretroviral therapy (HAART). The effect of HAART on the incidence of opportunistic infections will probably depend on reconstitution of antigen-specific CD4+ lymphocyte responses to important pathogens, including cytomegalovirus (CMV), the leading cause of blindness in AIDS. Several studies have demonstrated an important role for CD4+ lymphocytes in controlling CMV replication in vitro and in clinical studies. It is now possible to quantitate antigen-specific CD4+ lymphocyte responses by flow cytometry. Using this method, we studied CMV-specific CD4+ lymphocyte responses in individuals infected with HIV-1 with and without a history of active CMV-associated end organ disease (EOD), and in those with quiescent CMV EOD after ganciclovir therapy and HAART. The presence of active CMV-associated EOD strongly correlated with loss of CMV-specific lymphocyte responses (P = 0.0004). In contrast, patients with no history of CMV-associated EOD and most patients with quiescent EOD after HAART demonstrated strong CMV-specific CD4+ lymphocyte responses. These data indicate that the loss of CMV-specific CD4+ lymphocyte responses in individuals infected with HIV-1 who have active CMV EOD may be restored after ganciclovir therapy and HAART, which provides evidence for functional immune reconstitution to an important pathogen.

NK Cell Modulation of Murine Cytomegalovirus Retinitis

CMV retinitis, the most common ophthalmic infection of AIDS patients, causes blindness if left untreated. To study the role of NK cells in the modulation of CMV ocular infection, 9.0 × 102 plaque-forming units of the Smith strain of murine CMV (MCMV) was injected into the supraciliary space of the left eyes of BALB/c mice. Lysis of NK-sensitive target cells (YAC-1) by effectors from the draining lymph nodes peaked at day 5 postinfection, while the splenic cytolytic response was biphasic, with peaks at days 2 and 7 postinfection. Flow cytometry showed that NK cells (DX-5+) increased in spleens and eyes 5 days after supraciliary infection with MCMV compared with uninfected or mock-infected controls. Eight days after supraciliary injection with 9.0 × 102 plaque-forming units of MCMV, 7 of 10 NK-depleted mice developed retinitis compared with only 2 of 10 non-NK-depleted control mice. Poly(I-C) activation of NK cells in T cell-depleted animals protected mice from MCMV retinitis; only 2 of 10 mice in the poly(I-C)-treated group developed retinitis compared with 8 of 10 T cell-depleted, non-poly(I-C)-treated control mice. These results show the importance of NK cells in preventing MCMV retinitis and suggest that NK cells may also be involved in modulation of cytomegalovirus retinitis in human patients.

Cytomegalovirus retinitis and low-grade non-Hodgkin's lymphoma: case report and review of the literature

Patients with non-Hodgkin's lymphoma may develop retinal or choroidal lesions during the course of their disease. New immunosuppressive therapies currently used in reticuloendothelial malignancies have increased the incidence of opportunistic infections in this patient population. The differentiation of lymphomatous infiltration from opportunistic infection as a cause of chorioretinal infiltrates is critical, as the treatments are fundamentally different. We report a case of a patient with non-Hodgkin's lymphoma who developed a chorioretinal infiltrate that was initially thought to represent progressive disease. The patient received radiation treatment appropriate for intraocular lymphoma. The lesion progressed further and after reevaluation a diagnosis of cytomegalovirus retinitis was made and therapy initiated. Review of the literature for intraocular lymphoma and cytomegalovirus retinitis is provided and diagnostic strategies are described. We recommend analysis of intraocular fluid when there is difficulty in clinically differentiating intraocular lymphoma from opportunistic infection.

Role of retinal vascular endothelial cells in development of CMV retinitis

PURPOSE

Although cytomegalovirus (CMV) retinitis is known to occur in association with retinal microangiopathy in individuals with marked immunodeficiency, glial cells are believed to be the initial target cells in the development of retinitis. Moreover, it has been hypothesized that CMV gains access to the retinal glia because of altered vascular permeability. In an attempt to address the hypothesis, we studied 30 autopsy eyes of AIDS patients with systemic CMV infection, with or without clinically apparent CMV retinitis.

METHODS

The autopsy eyes were processed in three ways. First, dual immunohistochemical studies were done by using anti-CMV antibodies for immediate early, early, and late antigens. The retinal cell types infected with the virus were then determined by using anti-GFAP, anti-VonWillebrand's factor, neuronal specific enolase, and leukocyte marker CD68. Second, selected eyes were processed for in situ hybridization with DNA probe specific to CMV. Third, an eye with clinically apparent CMV retinitis was submitted for electron microscopic examination.

RESULTS

At the site of retinal necrosis in those eyes with a clinical diagnosis of CMV retinitis, the immunohistochemical, in situ hybridization, and ultrastructural examinations revealed that CMV was present primarily in the Müller cells and in perivascular glial cells. Adjacent to these infected cells, focal areas of positive staining for CMV antigen were seen in the glial cells, neuronal cells, and retinal pigment epithelial cells. At these sites most of the retinal capillaries were devoid of endothelial cells. Few vessels located at the advancing margin of retinal necrosis showed the presence of viral proteins in the endothelial cells.

CONCLUSIONS

The present results indicate that retinal vascular endothelial cells could be the initial target in the development of viral retinitis, with subsequent spread of the infection to perivascular glia, Müller cells, and other retinal cells, including the retinal pigment epithelium.

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.

Determination of antigen-specific memory/effector CD4+ T cell frequencies by flow cytometry: evidence for a novel, antigen-specific homeostatic mechanism in HIV-associated immunodeficiency

The highly regulated secretion of effector cytokines by CD4+ T cells plays a critical role in immune protection against pathogens such as cytomegalovirus. Here, we directly compare the frequency and functional characteristics of cytomegalovirus-specific CD4+ memory/effector T cells in normal and HIV+ subjects using a novel, highly efficient multiparameter flow cytometric assay that detects the rapid intracellular accumulation of cytokine(s) after short-term (6 h) in vitro antigen stimulation. Responses in this assay correlate precisely with independent measures of sensitization history (e.g., seroreactivity), and allow the simultaneous assessment of multiple cytokines in single effector T cells. Healthy HIV- individuals manifested an average of 0.71, 0.72, 0.38, and 0.06% CD4+ T cells responding to cytomegalovirus with gamma-IFN, TNF-alpha, IL-2, and IL-4 production, respectively, with the simultaneous production of gamma-IFN, TNF-alpha, and IL-2 being the most common effector phenotype. Significantly, overall cytomegalovirus-specific CD4+ effector frequencies were markedly higher among 40% of HIV+ subjects (2.7-8.0%), and demonstrated a predominately polarized gamma-IFN+/TNF-alpha+/IL-2-/IL-4- phenotype. In contrast, CD4+ effector frequencies for heterologous, nonubiquitous viruses such as the mumps virus were low or absent in the HIV+ group. These data suggest the existence of homeostatic mechanisms in HIV disease that selectively preserve memory T cell populations reactive with ubiquitous pathogens such as cytomegalovirus-likely at the expense of T cell memory to more sporadically encountered infectious agents.