Clinical significance of cytomegalovirus viremia in bone marrow transplantation

Early detection of cytomegalovirus (CMV) infection in bone marrow transplant patients by reverse transcription-PCR for CMV spliced late gene UL21.5: a two site evaluation

BACKGROUND

Bone marrow transplant (BMT) patients at risk of developing cytomegalovirus (CMV) pneumonitis are identified routinely by the early detection of virus in blood. For early diagnosis of CMV infection, the RNA-based approach demonstrates advantages when compared with the current CMV antigen and DNA detection methods.

OBJECTIVES

We have evaluated our previously developed reverse transcription-polymerase chain reaction (RT-PCR) to a spliced late CMV gene (SLG; J. Virol. Methods 56 (1996), 139) to monitor CMV infection in BMT patients at two clinical sites. The diagnostic value of the SLG RT-PCR was compared with the routine CMV antigen and DNA detection methods.

STUDY DESIGN

Weekly blood samples from BMT patients were tested for CMV during the first 3 months post-transplant. The qualitative SLG RT-PCR, semiquantitative DNA PCR, and viral antigen tests were compared. The RNA and DNA PCR results were analysed in terms of their temporal relationship and consistency of CMV detection and compared with CMV infection diagnosed by viral antigen tests.

RESULTS

Of the 101 BMT recipients studied, 25 developed CMV antigenemia and/or DNAemia resulting in symptomatic infection in two patients. All CMV PCR-positive patients were either CMV seropositive pretransplant or received marrow from seropositive donor. The highest incidence of CMV infection was seen in seropositive recipients (R+) irrespective of the donor's status. Detection of CMV infection by SLG RNA preceded CMV DNA detection by 0-2 weeks (median 1 week) and CMV antigen detection by 0-8 weeks (median 3 weeks). Once detected, the SLG RNA remained consistently positive before antiviral treatment was commenced. Both the SLG RNA and CMV DNA detection methods had the same clinical sensitivity, specificity, positive and negative predictive values of 100, 94, 80 and 100%, respectively.

CONCLUSIONS

The RT-PCR for SLG RNA proved to be the earliest indicator of CMV infection in BMT patients demonstrating a sustained pattern of CMV detection during the 3 months post-transplant period. Although very similar in its diagnostic performance to CMV DNA PCR the SLG RNA RT-PCR does not require quantitation and provides an efficient and ongoing indication of active CMV infection.

Reconstruction of the immune system after unrelated or partially matched T-cell-depleted bone marrow transplantation in children: functional analyses of lymphocytes and correlation with immunophenotypic recovery following transplantation

Reconstitution of the immune system following T-cell-depleted bone marrow transplantation (BMT) in children has yet to be fully elucidated. Thus, we prospectively studied the recovery of immune function in 64 children who underwent T-lymphocyte-depleted marrow transplants using either matched family member donors or matched unrelated donors. We measured in vitro posttransplantation proliferative responses to phytohemagglutinin (PHA), concanavalin A, pokeweed mitogen, and Candida albicans antigen and assessed unidirectional allogeneic mixed-lymphocyte culture (MLC) responses at various times. A total of 129 healthy individuals served as normal controls for these assays. Responses to T-cell mitogens normalized within 12 months posttransplantation, while MLC responses normalized by 9 months. The presence of graft-versus-host disease (grade II or greater) and cytomegalovirus infection was associated with delays in immune function recovery. Importantly, immune function recovery correlated temporally with a rise in peripheral lymphocyte count. In contrast, the CD4/CD8 ratio was not predictive of immune recovery. Knowledge of immune function recovery may guide clinicians in devising strategies to minimize the risk of infection post-BMT.

Comparison of three methods for extraction of viral nucleic acids from blood cultures

Reliable nucleic acid extraction techniques for blood specimens are required for the sensitive detection of viral DNA. Standardized procedures for processing blood specimens for the molecular detection of herpesviruses (cytomegalovirus [CMV], herpes simplex virus, varicella-zoster virus, and Epstein-Barr virus [EBV]) have not been established. Three methods were used to extract DNA from blood specimens from healthy donors and asymptomatic immunocompromised patients: (i) IsoQuick treatment of whole blood, (ii) extraction of the peripheral blood leukocytes by lysis (lysis buffer and proteinase K), and (iii) extraction of peripheral blood leukocytes with phenol-chloroform (sodium docecyl sulfate solution and proteinase K). All blood specimens from 25 healthy blood donors were negative for CMV, herpes simplex virus and varicella-zoster virus nucleic acid sequences, regardless of the extraction method, while three samples (12%) extracted by the lysis technique were positive for EBV DNA. Of 25 blood samples from asymptomatic immunocompromised patients, CMV and EBV each were detected in nine specimens by lysis extraction, four each by IsoQuick and four (CMV) and six (EBV) by the phenol-chloroform method. Our results indicate that the lysis method is optimal for the detection of CMV and EBV DNA sequences by PCR from the leukocytic fraction of blood specimens. DNA of these viruses is frequently present in blood specimens from asymptomatic immunocompromised patients and occasionally from healthy donors.

Cytomegaloviral virus infection in bone marrow transplantation recipients: strategies for prevention and treatment

Cytomegalovirus is major infectious pathogen following allogeneic bone marrow transplantation. In infected recipients, the virus is generally detected between 4 and 10 weeks after transplantation. Historically, CMV disease developed in 30-40% of seropositive recipients, the predominante manifestation being interstitial pneumonitis, which was generally lethal. Therapeutic interventions are discussed with special reference to the use of antiviral therapy for both treatment and prevention of CMV disease. The strategies developed in the bone marrow transplantation population to treat or prevent the development of CMV disease can be extrapolated to other patients groups who are immunosuppressed and at risk for developing clinical manifestations of CMV infection.

Cytomegalovirus infection and pneumonitis. Impact after isolated lung transplantation. Washington University Lung Transplant Group

Using aggressive surveillance of blood, bronchoalveolar lavage (BAL) fluid, and lung tissue, we sought to determine the incidence of cytomegalovirus (CMV) pneumonitis in isolated lung transplant recipients and to characterize its impact on pulmonary function, chronic rejection, and survival. Forty-six lung transplant recipients who survived greater than 30 days had prospective documentation of CMV infection in blood and BAL fluid and regular surveillance with transbronchial lung biopsy. CMV infection was documented in 92% of patients who were D-/R+, D+/R+, or D+/R-, and the incidence of histologically confirmed CMV pneumonitis among these patients was 75%. No D-/R- patient experienced CMV infection or disease. D+/R- patients experienced more frequent and severe episodes, and ganciclovir prophylaxis during the first 2 wk was not useful. CMV pneumonitis was accompanied by detectable radiographic changes in less than one third of cases. The detection of CMV in BAL fluid was not predictive of CMV pneumonitis on biopsy, except in D+/R- patients during the first 90 days after transplantation. There was no evidence of an adverse impact because of CMV infection on pulmonary function during the first year after transplantation. A relationship between CMV infection and bronchiolitis obliterans could not be documented; however, D+/R- patients had higher morbidity and a trend toward lower survival. In a multivariate analysis, D+/R- status was an independent predictor of death.

High levels of circulating cytomegalovirus DNA reflect visceral organ disease in viremic immunosuppressed patients other than marrow recipients

Although viremia is a hallmark of disseminated cytomegalovirus (CMV) infection, not all viremic patients have visceral organ CMV disease. We used blot hybridization with a cloned subgenomic probe to quantitate viral DNA in blood leukocytes of 60 viremic patients (25 with solid organ transplants, 20 with AIDS, and 15 marrow recipients) who had different clinical manifestations of CMV infection. The results are expressed as pg of viral DNA/10 micrograms of leukocyte DNA. Patients with AIDS or with solid organ transplants who had CMV visceral organ disease had the largest amounts of viral DNA in their granulocytes (median 632 and 237 pg, respectively). These amounts were significantly greater than those in similar viremic patients without CMV visceral disease (17 and 21 pg; P < 0.005 and 0.002, respectively). All patients in the study with > 150 pg of CMV DNA in their granulocytes had visceral CMV disease. The amounts of viral DNA in granulocytes of AIDS and organ transplant patients with CMV retinitis were low (median 22 pg). Marrow transplant patients were unique in that the amounts of CMV DNA in granulocytes were low whether CMV visceral organ disease was present (17 pg) or absent (14 pg). We conclude that high levels of circulating CMV DNA in viremic AIDS and solid organ transplant patients reflect viral involvement of visceral organs but not the retina. In marrow recipients, the severity of CMV disease, even when fatal, is not reflected quantitatively in peripheral blood leukocytes.

Low predictive value of polymerase chain reaction for diagnosis of cytomegalovirus disease in liver transplant recipients

The polymerase chain reaction (PCR) and viral culture techniques were prospectively compared for the detection of cytomegalovirus (CMV) in blood samples from 24 liver transplant recipients. Nine patients had one or more episodes of viremia, seven of which were clinically symptomatic infections. All samples in which CMV was isolated by culture were positive by the PCR. However, the PCR result was also positive for one or more samples from 11 patients who never developed CMV-related symptoms. Although the PCR is a very sensitive technique for CMV detection in blood samples from liver transplant recipients, it is not useful as a marker of symptomatic CMV disease.

Cytomegalovirus (CMV) excretion as a factor in the severity of CMV disease in kidney and simultaneous kidney and pancreas transplantation

The aim of the study was to evaluate the virological parameters associated with the severity of cytomegalovirus (CMV) disease in renal and simultaneous renal and pancreatic transplantation. The association of the viral profile and the severity of the viral disease was analysed taking into account different confounding variables susceptible to linkage with the severity of the CMV infection and the viral parameters. All the patients transplanted between 1 January 1989 and 31 December 1990, a total of 242, were prospectively followed by viral cultures in blood and urine and by serological methods using the detection of CMV-specific IgM and the complement fixation (CF) test. The samples were taken systematically each week for the first month and then at day 90, 180 and every 6 months and also in cases of clinical manifestations related to viral disease. CMV infection was diagnosed virologically by the presence of viraemia, viruria, IgM, or a significant rise in CMV antibody titre in CF. CMV disease was classified as asymptomatic, mild (fever and/or leukopenia), moderate (fever, leukopenia and liver abnormalities), severe (CMV pneumopathy and/or gastrointestinal disease) or fatal. The incidence of CMV infection was 65% (157/242): 32% asymptomatic, 36% mild, 30% moderate and 2% severe. The presence of IgM was associated with the severity of CMV disease: 51.4% of moderate and severe CMV infections in the group with IgM versus only 16% in the group without IgM (P < 0.0001). The risk of having severe or moderate CMV disease was 3.28 times higher in patients with positive IgM. However the serological changes in CF were not significantly associated with the severity of the viral disease since 34.6% of the patients with CF changes had a severe form versus 20.8% in the group without CF modification. Viruria was significantly associated with moderate or severe infection: 43.6% of the patients with viruria had severe infection versus only 12.5% in the patients without viruria (P < 0.0002). The risk of having moderate or severe CMV disease was 3.48 times higher in the patients with viruria. Viraemia was also associated with more severe CMV infection: 48.6% of moderate or severe CMV infection in the group of patients with viraemia versus 19% in the group without viraemia (P < 0.0001). The risk of having severe or moderate CMV infection was 2.58 times higher in the patients with viraemia. Viraemia was not more associated with severe CMV infection than viruria. Using the maximum likelihood ratio method and the logistic regression model, CMV-specific IgM, viruria and viraemia were each shown to be associated with the severity of CMV disease and the addition of one parameter to the other(s), whatever the type (except the CF changes) and whatever the order of this addition, did not remove the link between the severity and IgM, viruria and viremia. The incidence of severe and moderate CMV disease increased with the number of positive viral parameters (PVP) from 2% of moderate and severe infections in the group with one PVP, to 28% in the group with two PVP, to 39% in the group with three PVP and 68% in the group with four PVP (trend, 35.95; P < 0.0001). Taking the absolute risk of the group of patients without IgM, viruria or viraemia as the basal level, the observed relative risk of severe CMV infection varied from 6.45 in the group with positive IgM without viruria or viraemia, to 10.74 in the group with positive IgM and viruria without viraemia and to 22.5 in the group with the three positive parameters IgM, viruria and viraemia. The different potential confounding factors (recipient and donor serology, renal or renal and pancreatic transplantation, DR compatibility, rejection before CMV infection) did not modify the link between the viral profile and the severity of CMV disease. This study suggests that the severity of CMV disease might be linked to the overspread of the virus as well as to the consequences of a CMV-specific humoral immune response.

Comparison of two methods for rapid detection of cytomegalovirus viraemia in cell culture

Two methods for rapid CMV viraemia detection in cell culture with immunoperoxidase staining performed 40 h post-inoculation were compared, on 230 blood samples: (1) a 24-well plate centrifugation assay and (2) a 25-cm2-culture flask technique, without centrifugation. The flask technique was significantly more sensitive than the 24-well plate technique. Moreover, the flask assay was more cost-effective and offered other advantages such as easier sterile handling and less damage of the cell monolayer.

Infecção pelo citomegalovírus em pacientes com síndrome da imunodeficiência adquirida (AIDS): relações clínico-virológicas e anatomopatológicas

Com o objetivo de determinar a prevalência da infecção pelo Citomegalovírus (CMV) em pacientes com AIDS, bem como relacionar os achados clínico-virológicos decorrentes desta infecção com as repercussões anatomopatológicas, estudamos 50 pacientes adultos atendidos entre abril de 1986 a junho de 1987, em dois hospitais públicos de São Paulo (HSP e HSPE). Estes pacientes foram acompanhados clínica e laboratorialmente, por período médio de 2 meses com coletas seriadas de sangue, urina e saliva. Foram realizados isolamento do CMV em monocamadas de fibroblastos humanos e testes sorológicos de Imunofluorescência Indireta (IFI-IgG/IgM) e Reação Imunoenzimática (ELISA-IgG). No momento da admissão no estudo 20% (10/50) dos pacientes apresentavam anticorpos IgM CMV específicos e 100% (50/50) deles anticorpos IgG (IFI). Durante o acompanhamento, 5 pacientes inicialmente IgM negativos tornaram-se IgM positivos, sugerindo reativação ou reinfecção pelo CMV. O CMV foi isolado de sangue periférico em 12,5%, da urina em 23,2%, da saliva em 21,9% dos pacientes. Exames anatomopatológicos foram realizados em 24 pacientes, correspondendo a 60% dos pacientes que evoluiram para óbito durante o período de estudo. Corpúsculos de inclusão citomegálica característicos foram observados em 50% das necrópsias, sendo o aparelho digestivo, pulmões e supra-renais os sítios mais acometidos. Não se observou uma relação estatisticamente significante entre os achados clínicos e os achados virológicos e anatomopatológicos.

Predictive value of cytomegalovirus viraemia for the occurrence of CMV organ involvement in AIDS

In HIV-infected patients, the presence of cytomegalovirus (CMV) viraemia is predictive of the development of acquired immunodeficiency syndrome (AIDS), but it is not known whether it predicts further occurrence of CMV organ involvement. To assess the predictive value of CMV viraemia in the occurrence of CMV organ involvement, CMV blood cultures were performed at the onset of AIDS in 71 patients. They were prospectively followed up for at least 6 months, with a mean of 16.6 +/- 7 months (6-36 months). CMV viraemia was present in 28/71 patients (39.5%) at the onset of AIDS. CMV organ involvement occurred in 18/71 patients (25.4%) after 8.7 +/- 3.3 months. Fourteen of the 28 patients (50%) with early CMV viraemia developed CMV organ involvement after 7.7 +/- 6.3 months as compared with 4/43 patients (9.3%) who were not viraemic at the onset of AIDS with a mean follow-up of 11.8 +/- 3.8 months (P less than 0.001). At the time of CMV organ involvement, CMV viraemia, however, was present in 94.4% of the cases. No differences in survival was observed between initially viraemic and non-viraemic patients. No difference has found in mean CD4 cell count between viraemic and non-viraemic patients. This high predictive value of early CMV viraemia in AIDS for the occurrence of CMV organ involvement underlines the need for repeated search for CMV organ involvement when CMV viraemia is detected, and for less toxic antiviral drugs that might be used earlier.

Virus infections in bone marrow transplant recipients: a three year prospective study

Over three years 81 consecutive bone marrow transplant recipients (32 allogeneic and 49 autologous) who received prophylaxis with acyclovir, were studied for symptomatic virus infection. Thirty nine infections were documented in a total of 28 patients. Thirty two infections were mild, five were moderately severe, and two were severe. Cytomegalovirus infection occurred in only six allogeneic recipients. Herpes simplex virus and varicella zoster virus infections occurred infrequently. Seven patients who were considered at the time of death to have died due to an infectious cause were studied virologically at necropsy. In only one patient was a virus infection thought to have been the cause of death. Prophylaxis with acyclovir may have influenced the rate and clinical prominence of herpes virus infections. In this study viruses were considered to have had a relatively minor role in causing morbidity and mortality.

Rejection in liver transplantation

One hundred four liver transplant recipients were retrospectively reviewed for the incidence of liver allograft rejection, the response to antirejection therapy and the impact of rejection on graft and patient survival. Liver biopsies were performed weekly during episodes of graft dysfunction and to follow response to treatment. Baseline immunosuppression consisted of cyclosporine and low-dose prednisolone. Rejection was treated with steroids and with OKT3 as rescue. Azathioprine was given to patients with preoperative or perioperative renal insufficiency and was added to patients' treatment after the first sign of rejection. Seven complications were observed in approximately 1,100 liver biopsies, only one necessitating surgery. We found that 39.4% of the patients never experienced acute rejection, and 60.6% had at least one episode of acute rejection. Overall, 42.3% of the patients had only one episode of acute rejection, 13.5% had two, 3.8% had three and 1% had five episodes of acute rejection. Sixty of 63 first acute rejection episodes occurred within 21 days of transplant. Primary disease, sex or patient age had no significant influence on the incidence of rejection. There was a lower incidence of rejection (p less than 0.005) in patients transplanted after October, 1986, despite lower mean cyclosporine levels. Mean cyclosporine level during the first postoperative month was 679 ng per ml vs. a mean level of 910 ng per ml prior to October, 1986, when the immunosuppressive protocol was altered. Antirejection therapy was very effective in that only two of the 63 patients had graft failure due to acute rejection. Both of these patients were subsequently retransplanted.(ABSTRACT TRUNCATED AT 250 WORDS)

Hybridization techniques provide improved sensitivity for HCMV detection and allow quantitation of the virus in clinical samples

Hybridization techniques (slot-blot and in-situ hybridization assays) and immunostaining using murine monoclonal antibodies directed against different proteins of the human cytomegalovirus (HCMV) were compared for their sensitivity and specificity for detection of HCMV. A model system with HCMV infected human embryonic lung fibroblasts and lung biopsy specimens obtained from patients with culture positive HCMV interstitial pneumonia were used for evaluation of these techniques. The hybridization techniques were found to provide an improved sensitivity compared to immunostaining. Additionally a good correlation was found between the virus dose determined by TCID50 and the amount of viral DNA detected by slot-blot hybridization and by the number of autoradiographic silver grains per 100 cells per 2 weeks exposure time detected in the infected fibroblasts by in-situ hybridization. Thus, at least in the model system quantification of the virus was achieved by hybridization assays.

Detection of cytomegalovirus from blood leukocytes separated by sepracell-MN and Ficoll-Paque/Macrodex methods

Two density gradient separation techniques for separation of blood leukocytes were compared for the laboratory diagnosis of cytomegalovirus (CMV) viremia. Of 510 blood specimens processed by both methods, 76 (14.9%) yielded CMV. Of the 76 positive specimens, 66 (87%) and 65 (86%) were processed by the Ficoll-Paque/Macrodex (F-P/M; Macrodex is dextran 70 in normal saline; Pharmacia, Pisataway, N.J.) and Sepracell-MN methods, respectively. Of the 76 CMV-positive blood specimens, 72 (95%) were detected in shell vial cell cultures, whereas only 42 (55%) were detected in conventional tube cell cultures. The time for recognition of specific cytopathic effects due to CMV in tube cell cultures (8.0 versus 7.1 days), the number of fluorescent foci in each positive shell vial culture (19.3 versus 20.1), and the costs of the reagents ($3.50 versus $2.80) were similar and independent of the leukocyte separation method (F-P/M versus Sepracell-MN). Recovery of CMV from heparinized blood (F-P/M method) was similar to that from EDTA-anticoagulated blood (Sepracell-MN method). The Sepracell-MN method is a rapid and sensitive method for detection of CMV from blood specimens and is recommended as a replacement for the more tedious and time-consuming F-P/M procedure.

Predominant expression of circulating CD3+ lymphocytes bearing gamma T cell receptor in a prolonged immunodeficiency after allogeneic bone marrow transplantation

The cell surface expression of alpha:beta heterodimer was studied using WT31 monoclonal antibody, in peripheral blood lymphocytes (PBL) from a patient who developed a prolonged immunodeficiency after allogeneic bone marrow transplantation. This patient, grafted for chronic myelogenous leukemia, received T cell depleted bone marrow from her HLA, A, B, D matched sibling. The late occurrence of opportunistic infection, led us to analyze the phenotype of patient PBL. 70% of PBL were CD3+ and 29% WT31+, indicating that the majority of CD3+ PBL did not express the alpha:beta heterodimer. Transcription of the genes encoding the alpha, beta, and gamma chains was assessed in cell lines derived from PBL, by Northern blot analysis. We showed that the CD3+ WT31- subset expressed a truncated, beta mRNA (1.0 kb) and also truncated alpha transcript (1.4 kb). To determine the CD3-associated structure on CD3+ WT31- cell line, immunoprecipitation assays were performed using monoclonal anti-CD3 and an hetero antiserum against gamma peptides. These CD3+ WT31- cells expressed a disulfide linked dimer, composed of products of gamma gene (37 kD, 40 kD) and of undefined delta chain (45 kD). Functional analyses were performed in PBL before and after sorting with WT31 and anti-CD3 antibody. These circulating CD3+ WT31- cells were unable to proliferate when triggered with anti-T3 beads and they seemed to mediate a suppressor activity on CD3+ WT31+ cells.

Disseminated cytomegalovirus infection. Molecular analysis of virus and leukocyte interactions in viremia

Viremia is a hallmark of disseminated cytomegalovirus (CMV) infection and disease. Using conventional virus culture and a subgenomic cloned CMV DNA probe to detect viral DNA within leukocytes, we studied the virus-cell interactions involved in immunocompromised patients with viremic CMV infection. CMV was recovered by culture in 17/17 samples enriched for polymorphonuclear leukocytes. Viral DNA was detected by dot-blot hybridization in 16/17 (94%). In contrast, samples enriched for mononuclear cells yielded infectious CMV in culture in only 7/15 (47%) instances; nonetheless, viral DNA was present in 16/17 samples probed. The quantity of CMV DNA in polymorphonuclear cells was significantly greater than in mononuclear leukocytes (mean 13.1 vs. 9.1 estimated viral genome equivalents per 100 cells, respectively), and CMV was always recovered from these cells regardless of the amount of viral DNA present. Yet, when the amounts of CMV DNA were virtually identical in granulocytes and mononuclear cells (6.3 and 7.1 genomic equivalents, respectively) collected simultaneously, infectious CMV could not be recovered from mononuclear cells. Although several interpretations are possible, these data are consistent with the view that CMV exists within granulocytes in a mature infectious form during viremia. The virus interactions with mononuclear cells appear to be more complex, particularly in those cells that contain CMV DNA but do not yield infectious virus.

Enhanced interferon-alpha/beta (IFN-alpha/beta) and defective IFN-gamma production in chronic graft versus host disease: a potential mechanism for immunosuppression

Immunosuppression is a well-characterized consequence of chronic graft-versus-host disease (GVHD). We have previously shown that interferon (IFN) is produced in high levels during acute GVHD. Our objective in this study was to determine if IFN, as a cytokine with known immunosuppressive qualities, could be detected in mice experiencing chronic GVHD-induced immunosuppression. Two different experimental models were used to induce chronic GVHD. The first model involved the injection of parental strain spleen cells into adult F1 hybrids (AJ----B6AF1), while the second model utilized GVHD induced across minor histocompatibility barriers (B10.D2----BALB/c). Results indicated that significant levels of serum IFN-alpha/beta are present in mice undergoing chronic GVHD. Spleen cells from chronic GVHD mice were also shown to produce significant levels of IFN-alpha/beta upon in vitro culture in medium only. This IFN-alpha/beta production was greatly increased when GVHD spleen cells were cultured with either concanavalin A (Con A) or IL-2. In contrast, IFN-gamma production was undetectable in these Con A- or IL-2-containing cultures. Additionally, these same spleen cells which produced high levels of IFN-alpha/beta were immunosuppressed as measured by mitogen-induced cell proliferation. These results suggest that IFN-gamma production is defective in GVHD spleen cells, and that the presence of high IFN-alpha/beta production by GVHD mice may contribute to the immunosuppression associated with chronic GVHD.

Cytomegalovirus (CMV) infections in patients receiving CMV-IgG-hyperimmunoglobulin prophylaxis after bone-marrow transplantation

Conditioning therapy with aggressive chemotherapy and irradiation induces a state of transient combined immunodeficiency in bone-marrow transplant recipients. This promotes the occurrence of severe cytomegalovirus (CMV) infections, the most frequent lethal complication after bone-marrow transplantation (BMT) at present. Forty-four BMT recipients received CMV-IgG-hyperimmunoglobulin for CMV prophylaxis intravenously. The efficacy of this prophylaxis and possible risk factors for the occurrence of CMV-induced interstitial pneumonia (IP) were analyzed. Risk factors for the promotion of a CMV-IP were: additional immunosuppressive therapy after BMT, CMV-positive serostatus of the recipient, CMV-seropositive granulocyte transfusion, CMV infection immediately prior to BMT, and HLA-haploidentical BMT. In this study the incidence of graft-versus-host disease was low and was not associated with the incidence of CMV infections. The use of T-cell-depleted grafts did not result in increased CMV infections or IP and may possibly have improved the immunological reconstitution.

The biology of human cytomegalovirus infection after bone marrow transplantation

Human cytomegalovirus (HCMV) infection remains the most common infectious cause of morbidity after bone marrow transplantation (BMT). In a prospective study of 127 BMT recipients who received blood cultures for HCMV between days 28 to 105 after marrow grafting, HCMV viremia occurred in 68 patients (53.4%). Twenty patients (15.7%) had one or two positive cultures, and 48 (37.7%) had greater than or equal to three positive cultures. Fifty-nine patients (46.4%) had no viremia. HCMV-associated interstitial pneumonia (HCMV-IP) occurred in one-third of the viremic patients. Quantitative measurements of infectious HCMV or of HCMV DNA in lung tissue were made to determine whether HCMV replication correlated with clinical disease. Using DNA probes, viral DNA was measured by dot-blot hybridization, and this correlated with infectious HCMV. However, neither HCMV DNA nor HCMV viral titer correlated with time from the onset of pneumonia to death. The hypothesis is presented that HCMV-IP is caused by immunologic events induced after HCMV infection. In this model HCMV alterations in recipient cell surfaces induce donor alloreactivity to minor histocompatibility differences and lead to the subsequent pneumonitis which we term HCMV-IP. This model suggests that prevention of HCMV-IP will require early use of antiviral therapy or late use of immune response modification.