CYTOMEGALOVIRUS

IL-33/ST2 pathway drives regulatory T cell dependent suppression of liver damage upon cytomegalovirus infection

Regulatory T (Treg) cells dampen an exaggerated immune response to viral infections in order to avoid immunopathology. Cytomegaloviruses (CMVs) are herpesviruses usually causing asymptomatic infection in immunocompetent hosts and induce strong cellular immunity which provides protection against CMV disease. It remains unclear how these persistent viruses manage to avoid induction of immunopathology not only during the acute infection but also during life-long persistence and virus reactivation. This may be due to numerous viral immunoevasion strategies used to specifically modulate immune responses but also induction of Treg cells by CMV infection. Here we demonstrate that liver Treg cells are strongly induced in mice infected with murine CMV (MCMV). The depletion of Treg cells results in severe hepatitis and liver damage without alterations in the virus load. Moreover, liver Treg cells show a high expression of ST2, a cellular receptor for tissue alarmin IL-33, which is strongly upregulated in the liver of infected mice. We demonstrated that IL-33 signaling is crucial for Treg cell accumulation after MCMV infection and ST2-deficient mice show a more pronounced liver pathology and higher mortality compared to infected control mice. These results illustrate the importance of IL-33 in the suppressive function of liver Treg cells during CMV infection.

Treg cells are crucial for immune homeostasis and for dampening immune response to several diseased conditions, including viral infections. Murine cytomegalovirus (MCMV) is a herpesvirus with pathogenic potential, so that early immune mechanisms are essential in controlling virus and protecting from virus-induced pathology. Studies on Foxp3⁺ Treg cells have revealed their inhibitory role on the early T cell response to MCMV infection and have suggested Treg cells as a target of MCMV’s immunoevasion mechanisms. Here we demonstrate that the number and activation status of liver Treg cells is strongly induced upon MCMV infection in order to protect the host from severe liver damage. They constitutively express high amounts of IL-33 receptor ST2 and their accumulation depends on IL-33, which is released as a tissue alarmin after the cell damage. For the first time, we show an immunoregulatory role of IL-33-dependent Treg cells in the liver of MCMV infected mice and their suppression of MCMV-induced immunopathology.

Host and donor immune responses contribute to antiviral effects of amotosalen-treated donor lymphocytes following early posttransplant cytomegalovirus infection

We have previously shown that amotosalen-treated splenocytes rescued allorecipients from a lethal dose of mouse CMV (MCMV) administered on day 0 in experimental parent C57BL/6-->CB6F1 allogeneic bone marrow transplant. In this study, we investigated the mechanism of antiviral activity of amotosalen-treated donor splenocytes when sublethal MCMV infections were administered 7 days posttransplant. Recipients of 3 x 10(6) untreated splenocytes were used as control. Following MCMV infection, recipients of untreated splenocytes had 40% early mortality due to acute graft-vs-host disease compared with no deaths among recipients of 10 x 10(6) treated splenocytes. However, recipients of both types of donor splenocytes effectively cleared MCMV from their liver. Like the untreated CD8(+) T cells, amotosalen-treated CD8(+) T cells equally retained their in vivo CTL activity against MCMV early peptide-pulsed targets and expressed similar levels of granzyme B within 11 days of infection. In contrast to full donor chimerism in recipients of untreated splenocytes, recipients of amotosalen-treated splenocytes showed mixed chimerism with both donor spleen- and host-derived anti-MCMV CD8(+) T cells in their blood and lymphoid organs, with significantly higher numbers of host-derived CD4(-)CD8(-) (double negative) T cells in the spleens of recipients of treated splenocytes compared with the recipients of untreated splenocytes. Additionally, recipients of amotosalen-treated splenocytes had lower levels of serum IFN-gamma and TNF-alpha in response to MCMV infection compared with untreated recipients. Thus, adoptive immunotherapy with treated T cells is a novel therapeutic approach that facilitates hematopoietic engraftment and permits antiviral immunity of both donor and host T cells without graft-vs-host disease.

Withdrawal of maintenance therapy for cytomegalovirus retinitis in AIDS patients exhibiting immunological response to HAART

BACKGROUND: Before the introduction of highly active antiretroviral therapy (HAART), CMV retinitis was a common complication in patients with advanced HIV disease and the therapy was well established; it consisted of an induction phase to control the infection with ganciclovir, followed by a lifelong maintenance phase to avoid or delay relapses. METHODS: To determine the safety of CMV maintenance therapy withdrawal in patients with immune recovery after HAART, 35 patients with treated CMV retinitis, on maintenance therapy, with CD4+ cell count greater than 100 cells/mm³ for at least three months, but almost all patients presented these values for more than six months and viral load < 30000 copies/mL, were prospectively evaluated for the recurrence of CMV disease. Maintenance therapy was withdrawal at inclusion, and patients were monitored for at least 48 weeks by clinical and ophthalmologic evaluations, and by determination of CMV viremia markers (antigenemia-pp65), CD4+/CD8+ counts and plasma HIV RNA levels. Lymphoproliferative assays were performed on 26/35 patients. RESULTS: From 35 patients included, only one had confirmed reactivation of CMV retinitis, at day 120 of follow-up. No patient returned positive antigenemia tests. No correlation between lymphoproliferative assays and CD4+ counts was observed. CONCLUSION: CMV retinitis maintenance therapy discontinuation is safe for those patients with quantitative immune recovery after HAART.

Cytomegalovirus ileitis associated with goblet cell carcinoid tumour of the appendix

We report a female patient with cytomegalovirus (CMV) terminal ileitis and CMV viraemia, associated with a metastatic goblet cell carcinoid (GCC) tumour of the appendix. She was treated with ileocaecal resection followed by ganciclovir. We highlight the importance of vigilant histopathological assessment and discuss the existing literature on gastrointestinal CMV infection in immunocompetent patients.

Endoscopic diagnosis of cytomegalovirus infection of upper gastrointestinal tract in solid organ transplant recipients: Hungarian single-center experience

BACKGROUND

Cytomegalovirus (CMV) is considered to be the major cause of upper gastrointestinal (GI) symptoms in organ transplant recipients. In the diagnosis of GI CMV infection the detection of the virus in the mucosa is essential. The aim of the study was to evaluate the significance of CMV, detected in biopsy specimens from stomach and duodenum of solid organ transplant recipients.

METHODS

Data of 227 elective upper endoscopies on symptomatic organ transplant recipients were evaluated for clinical symptoms, endoscopic changes and conventional histologic alterations of mucosal biopsy samples. Qualitative PCR was performed for detection of the presence of CMV-DNA in each biopsy materials.

RESULTS

CMV-DNA was detected in biopsy samples of 91 patients (40.1%) while only in 20 cases (8.8%) the signs of CMV infections were found by conventional histology (p < 0.00001). No considerable differences could be observed in symptomatic, histologic alterations between CMV-PCR positive and negative groups. There were no endoscopic changes in 25.3% of CMV-PCR positive and 5.1% of negative patients.

CONCLUSIONS

Qualitative PCR is an accurate method for the detection of CMV in the mucosa of the GI tract. Further investigations are needed for determination of the exact pathological role of detected CMV.

Immune evasion proteins of human cytomegalovirus do not prevent a diverse CD8+ cytotoxic T-cell response in natural infection

Although cytomegalovirus (CMV) expresses proteins that interfere with antigen presentation by class I major histocompatibility complex (MHC) molecules, CD8+ cytotoxic T cells (CTLs) are indispensable for controlling infection and maintaining latency. Here, a cytokine flow cytometry assay that employs fibroblasts infected with a mutant strain of CMV (RV798), which is deleted of the 4 viral genes that are responsible for interfering with class I MHC presentation, was used to examine the frequency and specificity of the CD8+ CTLs to CMV in immunocompetent CMV-seropositive individuals. A large fraction of the CD8+ CTL response was found to be specific for viral antigens expressed during the immediate early and early phases of virus replication and presented by fibroblasts infected with RV798 but not wild-type CMV. These results demonstrate that the inhibition of class I antigen presentation observed in CMV-infected cells in vitro is not sufficient to prevent the induction of a broad repertoire of CD8+ CTLs after natural infection in vivo. Thus, reconstitution of T-cell immunity in immunodeficient patients by cell therapy or by vaccination may need to target multiple viral antigens to completely restore immunologic control of CMV.

Herpesviruses: emerging nosocomial pathogens?

BACKGROUND

Herpesviruses are ubiquitous pathogens that are known to cause infection in humans and animals. It is likely that more than 90% of adults have been infected by one or more herpesviruses. As hospitalized patients become increasingly immunosuppressed by virtue of illness or therapies, it is increasingly likely that human herpesvirus infection will become manifest in the hospital. Whether these manifestations represent manifestations of reactivated latent disease or true nosocomial infections is an open question.

METHODS

Review of the pertinent English-language literature.

RESULTS

There are eight known herpesviruses that cause disease in humans. Herpesviruses are double-stranded DNA viruses. The prototypical structure consists of an inner DNA core that is encased within a nucleocapsid that is icosahedral in configuration and consists of capsomere subunits. Herpesvirus infection generally occurs when virus is transmitted in oral secretions from an infected to a naive host. Clinical reactivation syndromes can occur in transplant patients, cancer chemotherapy patients, and patients with acquired immunodeficiency syndrome. Life-threatening infections are most closely associated with human herpesvirus-5 (cytomegalovirus), whereas the relationships between human herpesvirus-7 and clinical disease are largely undefined.

CONCLUSION

Clinical expressions of herpesvirus in surgical patients are not nosocomial infections, but are in the vast majority of cases the reactivation of latent infection. Reactivation disease can be lethal to the immunosuppressed host.

Mycobacterial and nonbacterial pulmonary complications in hospitalized patients with human immunodeficiency virus infection: a prospective, cohort study

BACKGROUND

A prospective observational study was done to describe nonbacterial pulmonary complications in hospitalized patients with human immunodeficiency virus (HIV) infection.

METHODS

The study included 1,225 consecutive hospital admissions of 599 HIV-infected patients treated from April 1995 through March 1998. Data included demographics, risk factors for HIV infection, Acute Physiology and Chronic Health Evaluation (APACHE) II score, pulmonary complications, CD4+ lymphocyte count, hospital stay and case-fatality rate.

RESULTS

Patient age (mean +/- SD) was 38.2 +/- 8.9 years, 62% were men, and 84% were African American. The median APACHE II score was 14, and median CD4+ lymphocyte count was 60/microL. Pulmonary complications were Pneumocystis carinii pneumonia (85) in 78 patients, Mycobacterium avium complex (51) in 38, Mycobacterium tuberculosis (40) in 35, Mycobacterium gordonae (11) in 11, Mycobacterium kansasii (10) in 9, Cytomegalovirus (10) in 10, Nocardia asteroides (3) in 3, fungus ball (2) in 2, respiratory syncytial virus (1), herpes simplex virus (1), Histoplasma capsulatum (1), lymphoma (3) in 3, bronchogenic carcinoma (2) in 2, and Kaposi sarcoma (1). The case-fatality rate of patients was 11% with Pneumocystis carinii pneumonia; 5%, Mycobacterium tuberculosis; 6%, Mycobacterium avium complex; and 7%, noninfectious pulmonary complications.

CONCLUSION

Most pulmonary complications in hospitalized patients with HIV are from Pneumocystis and mycobacterial infection.

Infectious diarrhea in human immunodeficiency virus

Chronic HIV-associated diarrhea is currently a field in flux. Improved noninvasive diagnostic tests, improved pathogen-specific regimens, and better empiric therapies may change some of the assumptions used to select algorithms for diagnostic evaluation and management. Any shift in the cause of diarrhea from pathogen-associated to idiopathic or a reduction in the overall incidence of diarrhea would have considerable impact. It is unclear how significant the problem of pathogen relapse in previous responders will become. Existing studies reviewed in this article show that the high diagnostic yield of endoscopy when stool tests are negative, coupled with significantly better outcomes when pathogens are identified, support the current practice of routine endoscopic evaluation. There currently are scant data on the economic impact of HIV-associated diarrhea as it relates to pathogen-specific and empiric therapy in the era of protease inhibitors. Such data would be integral to future evaluation of the impact of diagnostic and therapeutic strategies.

In vivo acute depletion of CD8(+) T cells before murine cytomegalovirus infection upregulated innate antiviral activity of natural killer cells

In this study, we investigated the effect of depletion of CD8(+) T cells on the activity of natural killer (NK) cells at an early phase of murine cytomegalovirus (MCMV) infection. For CD8(+) T cell depletion, mice were intraperitoneally treated with anti-CD8 mAb, purified from 2.43 hybridoma, for 2 consecutive days before or after infection. Three days after infection, we found that an acute depletion of CD8(+) T cells before infection caused a significant decrease in the viral load in liver and spleen. This effect coincided with an increase in numbers of CD3(-) NK1.1(+) cells in spleen and their expression of the early activation molecule CD69. Although cytolytic activity of NK cells increased on day 3 of infection in CD8-depleted mice, the level of IFN-gamma decreased in serum and supernatant of cultured spleen cells. In contrast to the effect of acute depletion of CD8(+) T cells before infection, the depletion after infection had no effect on the viral load or number and cytolytic function of NK cells. Lack of effects of CD8(+) T cell depletion on the viral load and NK cytolytic activity is also observed in CD8(+) knockout mice. In conclusion, the results suggest that an acute depletion of CD8(+) T cells before MCMV infection effectively upregulated the antiviral activity of NK cells. This effect appears to be mediated through an increase in numbers, activation and cytolytic activity of NK cells.

Protective effect of black seed oil from Nigella sativa against murine cytomegalovirus infection

In this study, antiviral effect of black seed oil (BSO) from Nigella sativa was investigated using murine cytomegalovirus (MCMV) as a model. The viral load and innate immunity mediated by NK cells and M&phi; during early stage of the infection were analyzed. Intraperitoneal (i.p.) administration of BSO to BALB/c mice, a susceptible strain of MCMV infection, strikingly inhibited the virus titers in spleen and liver on day 3 of infection with 1x10(5) PFU MCMV. This effect coincided with an increase in serum level of IFN-gamma. Although BSO treatment decreased both number and cytolytic function of NK cells on day 3 of infection, it increased numbers of M&phi; and CD4(+) T cells. On day 10 of infection, the virus titer was undetectable in spleen and liver of BSO-treated mice, while it was detectable in control mice. Although spleen of both control and BSO-treated mice showed similar CTL activities on day 10 after infection, serum level of IFN-gamma in BSO-treated mice was higher. Furthermore, BSO treatment upregulated suppressor function of M&phi; in spleen. These results show that BSO exhibited a striking antiviral effect against MCMV infection which may be mediated by increasing of M&phi; number and function, and IFN-gamma production.

Outcome of AIDS-associated cytomegalovirus colitis in the era of potent antiretroviral therapy

The effect of protease inhibitors (PIs) on the outcome of AIDS-associated cytomegalovirus (CMV) colitis is unknown. The aim of this study was to determine the impact of PIs on the recurrence of CMV disease and long-term survival in a large cohort of acquired immunodeficiency syndrome (AIDS) patients with CMV colitis. We reviewed the medical records of 252 AIDS patients who were diagnosed with CMV colitis by colonoscopy between January 1992 and January 1997 at Bellevue Hospital (New York, NY, U.S.A.). Follow-up data were obtained from chart review and direct telephone contact. A complete response to ganciclovir and/or foscarnet therapy was seen in 87.0% of the patients. Recurrence of CMV colitis occurred in 53.1% of patients and was significantly less common in those who received maintenance therapy (36.1% vs. 56.7%; p = 0.03) and in those who were treated with PIs (22.8% vs. 71.9%; p < 0.001). During follow-up. 69.3% of patients died. Multivariate analysis using Cox regression showed that mortality was increased in patients with recurrent CMV colitis (relative risk [RR] of death, 1.7: 95% CI, 1.1-2.6; p = 0.02) and comorbid disease (RR, 1.5: 95% CI, 1.1-2.2; p = 0.02), and decreased in those who were treated with PIs (RR, 0.42; 95% CI, 0.3-0.7; p = 0.001). The median survival was 71 weeks and was significantly longer in patients who were treated with PIs than in those who did not receive these potent anti-retroviral medications (99 vs. 51 weeks; p < 0.001). PIs significantly improve the outcome of AIDS-associated CMV colitis.

Protective effects of hochu-ekki-to, a Chinese traditional herbal medicine against murine cytomegalovirus infection

The innate immunity against murine cytomegalovirus (MCMV) at the early phase of infection is mediated by NK cells and macrophages. We studied the effects of hochu-ekki-to (HET), a traditional Chinese herbal medicine, on the regulation of innate immunity mediated by NK cells and macrophages. We found the oral administration of HET to increase both the number of leukocytes in the spleen and liver and the splenic NK cell cytotoxicity associated with the increased induction of serum IFN-alpha/beta after an MCMV infection but it had no effect on liver NK cells. However, no differences were found in the serum IL-12, IFN-gamma, TNF-alpha and nitric oxide (NO) production in the culture of macrophages between the HET- and PBS-treated mice on day 2 after MCMV infection. In addition, HET-treated splenic and peritoneal macrophages were found to show a higher intrinsic resistance against in vitro MCMV infection than that of PBS-treated mice. Therefore, the HET-induced effects on NK cells and macrophages selectively reduced the viral load in the spleen but not in the liver at an early phase of MCMV infection. HET may thus be useful in the treatment of human cytomegalovirus infection which commonly occurs in HIV-infected AIDS patients.

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 enteritis: a highly lethal condition requiring early detection and intervention

Cytomegalovirus infection causing symptomatic enteritis is most usually associated with immunosuppressed transplant patients or patients positive for human immunodeficiency virus. Most reports studying this illness are small and do not clearly define the risk factors or mortality rates.

METHODS

The present study retrospectively reviewed the charts of 67 patients with biopsy-proven cytomegalovirus enteritis (esophageal, gastric, small bowel, and colonic) to define and to investigate factors that influence survival. Patients were classified into four groups based on underlying medical condition: 1) patients positive for human immunodeficiency virus; 2) transplant patients receiving immunosuppressive medications; 3) immunosuppressed nontransplant patients; and 4) otherwise healthy individuals. Mortality rates based on underlying medical condition, location of intestinal cytomegalovirus infection, cytomegalovirus therapy, age, and average days to institution of treatment were defined and statistically assessed.

RESULTS

Mortality was significantly greater in the normal patient group (80 percent) than in the transplant (21 percent), other immunosuppressed (44 percent), or human immunodeficiency virus-positive (75 percent) groups (P = 0.0006, Cochran-Mantel-Haenszel statistics). There was no difference in mortality based on intestinal location of disease or treatment modality (surgery, medical therapy, or both). Cohorts of patients older than 65 years had a statistically higher mortality rate vs. those younger than 65 years old (68 vs. 38 percent; P = 0.05, Cochran-Mantel-Haenszel statistics). Statistically increased mortality was also associated with increased time from hospital admission to institution of cytomegalovirus treatment, whether therapy was medication alone or medication and surgery (P < 0.05, exact Wilcoxon's test).

CONCLUSIONS

1) Lethal cytomegalovirus enteritis can arise in patient populations not typically identified as being at risk for this disorder, including normal individuals. 2) Mortality in cytomegalovirus enteritis is adversely associated with age older than 65 years and increased time to institution of therapy but is not affected by anatomic site of infection or particular form of treatment. Paradoxically, in this study, normal patients had the highest mortality, which we attribute to a low index of suspicion and relatively late institution of therapy.

Diagnosing HIV-related disease: using the CD4 count as a guide

OBJECTIVE

To summarize current information on the relation between CD4 counts and the risk of different HIV-related diseases.

MEASUREMENTS AND MAIN RESULTS

MEDLINE search of English language articles between 1985 and 1996 using the medical subject heading (MeSH) term "CD4 lymphocyte count" and searches using key words of multiple HIV-related diseases were conducted. Some HIV-related diseases can be stratified to different CD4 count levels. Regardless of their CD4 count, HIV-infected patients are susceptible to sinusitis, Kaposi's sarcoma, community-acquired pneumonia, and oral hairy leukoplakia. In advanced HIV, when CD4 is below 200/mm3, Pneumocystis carinii pneumonia, toxoplasmosis, progressive multifocal leukoencephalopathy, Mycobacterium avium complex, molluscum contagiosum, and bacillary angiomatosis all increase in incidence. In very advanced HIV disease, when CD4 counts are below 50/mm3, patients are at risk of pseudomonas pneumonia, cytomegalovirus retinitis, central nervous system lymphoma, aspergillosis, and disseminated histoplasmosis.

Cytomegalovirus Infection Presenting as Chronic Sinusitis and Nasal Polyposis: A Case Report

Cytomegalovirus (CMV) is the most common viral opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS), affecting up to 90% of patients. CMV can manifest as primary, latent or chronic persistent infection, most commonly appearing as retinitis, encephalitis or gastrointestinal disease. Other less common presentations, including otolaryngologic expression of the virus, have also been noted. Described here is the first known documented case of CMV with both chronic sinusitis and nasal polyposis in an AIDS patient.

Granulocyte colony-stimulating factor use is associated with decreased bacteremia and increased survival in neutropenic HIV-infected patients

BACKGROUND

Neutropenia occurs in up to 17% of human immunodeficiency virus (HIV)-infected individuals. Although granulocyte colony-stimulating factor (G-CSF) can reverse HIV-related neutropenia, it is not established that this therapy can reduce bacterial infections and affect survival.

METHODS

A retrospective cohort study of 152 neutropenic, HIV-infected patients was performed to determine the therapeutic utility of G-CSF. Medical records of 71 patients who received G-CSF and 81 patients who never received G-CSF, during the years of 1991 to 1994 at Parkland Memorial Hospital, were reviewed for the incidence of bacteremia, G-CSF use, antiretroviral therapy (AR), Pneumocystis carinii pneumonia prophylaxis (PCPP), and opportunistic infections (OI).

RESULTS

The two patient groups had similar baseline characteristics including CD4 count (37 cells/mm3 versus 40 cells/ mm3, P=0.7). Univariate analysis revealed and trend toward decreased rates of all bacteremias in the G-CSF-treated group compared with the controls (0.54 bacteremias/100 patient months versus 2.2 bacteremias/100 patient months, P=0.064) and a marked decrease in the rates of gram-negative rod bacteremias in the G-CSF-treated group compared with the untreated group (0.09 gram-negative rod bacteremias/100 patient months versus 1.7 gram-negative rod bacteremias/100 patient months, P=0.002). In a multivariate analysis, significant decreased risk for bacteremia was found with G-CSF use (odds ratio [OR]=0.15, P=0.02). Survival was longer in patients treated with G-CSF than in the untreated group (median: 397 days versus 165 days). Multivariate analysis using Cox Proportional Hazards Model showed decreased risk of death in patients treated with G-CSF, ARs, PCPP.

CONCLUSIONS

We conclude that G-CSF use is associated with decreased bacteremias and is associated with prolonged survival in neutropenic, HIV-infected patients.

T cell therapy of human CMV and EBV infection in immunocompromised hosts

Acute virus infections in normal hosts are typically controlled by the development of a host immune response that includes MHC-restricted virus-specific T cells. Many viruses have developed methods to evade T cell recognition to facilitate initial infection and the establishment of a persistent infection in the host. Human cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are ubiquitous human pathogens that utilise novel strategies to evade immune elimination. Despite these evasion methods, CD4(+) and CD8(+) T cells expressing alphabeta T cell receptors have been shown to play a pivotal role in controlling initial infection and in maintaining CMV and EBV in a latent state. However, in settings of iatrogenic or acquired T cell deficiency, primary infection or reactivation of CMV and EBV frequently progresses to cause life threatening disease. In this article the role of MHC-restricted CD8(+) and CD4(+) T cell responses in controlling CMV and EBV infections in healthy individuals and the development of novel strategies to restore protective T cell immunity to deficient hosts by the adoptive transfer of virus-specific T cells is reviewed. Copyright 1997 John Wiley & Sons, Ltd.

Reconstitution of cellular immunity against cytomegalovirus in recipients of allogeneic bone marrow by transfer of T-cell clones from the donor

BACKGROUND

Cytomegalovirus (CMV) disease in immunocompromised patients correlates with a deficiency of CD8+ cytotoxic T lymphocytes specific for CMV. We evaluated the safety and immunologic effects of immunotherapy with clones of these lymphocytes in recipients of allogeneic bone marrow transplants.

METHODS

Clones of CD8+ cytotoxic T cells specific for CMV proteins were isolated from the blood of bone marrow donors. Fourteen patients each received four intravenous infusions of these clones from their donors beginning 30 to 40 days after marrow transplantation. The reconstitution of cellular immunity against CMV was monitored before and during the period of infusions and for up to 12 weeks after the final infusion. The rearranged genes encoding the T-cell receptor served as markers in evaluating the persistence of the transferred T cells.

RESULTS

No toxic effects related to the infusions were observed. Cytotoxic T cells specific for CMV were reconstituted in all patients. In vitro measurements showed that cytotoxic activity against CMV was significantly increased (P < 0.001) after the infusions in 11 patients who were deficient in such activity before therapy. The level of activity achieved after the infusions was similar to that measured in the donors. Analysis of rearranged T-cell-receptor genes in T cells obtained from two recipients indicated that the transferred clones persisted for at least 12 weeks. Cytotoxic-T-cell activity declined in patients deficient in CD4+ T-helper cells specific for CMV, suggesting that helper-T-cell function is needed for the persistence of transferred CD8+ T cells. Neither CMV viremia nor CMV disease developed in any of the 14 patients.

CONCLUSIONS

The transfer of CMV-specific clones of CD8+ T cells derived from the bone marrow donor is a safe and effective way to reconstitute cellular immunity against CMV after allogeneic marrow transplantation.