Treatment of cytomegalovirus pneumonia after marrow transplant with combined vidarabine and human leukocyte interferon

Chapter 3 Antiviral drugs: general considerations

The development of an antiviral drug as well as of other drugs is a long process. In most programmes the screening and evaluation start using inhibition of virus multiplication in cell cultures, but in some instances the screening starts in animal models of different viral diseases. In these cases, the mechanism of action has to be analyzed after the in vivo effect has been found. It is not possible to specify precisely the time and resources required in a newly started project to find a compound active against a virus infection but 5-10 years is a reasonable estimation. For some viruses such as herpesviruses, where a number of active inhibitors are already known, the task is simpler than it is to find inhibitors of a virus such as influenza against which only a few active inhibitors have been reported. Evaluation of clinical efficacy in humans is a large and difficult part of the development of an antiviral drug. The number of uncontrolled clinical studies claiming efficacy of different drugs against viral diseases is depressingly large. It is essential to perform double-blind, placebo-controlled and statistically well evaluated studies to be able to judge the clinical efficacy of an antiviral drug. As the knowledge of the detailed natural history and molecular biology of viral diseases and viruses themselves increases, one will obviously have better opportunities to find new drugs. Methods such as X-ray diffraction measurement and NMR determinations will probably lead to a detailed understanding of the structures and interactions taking place at the active site of viral enzymes and their cellular counterparts.

Respiratory infections: pneumonia, lung abscess, and empyema

Pneumonia is an important clinical problem that affects children of all ages. Although effectively treated on an outpatient basis in the majority of cases, some children with respiratory infections still require hospitalization. This may be particularly true for patients with immunocompromise, for whom the lung represents the most common site of infection. Furthermore, respiratory infections represent a significant source of morbidity and mortality in this patient population. This article focuses on the clinical presentation, etiology, and treatment of childhood pneumonia, with special consideration given to the immunocompromised child. Two specific complications of pneumonia, lung abscess and empyema, are discussed.

Pneumonia in the compromised host including cancer patients and transplant patients

Pneumonia remains a major cause of morbidity and mortality in the immunocompromised host. The type and timing of immunosuppression will predispose the patient to infections with certain pathogens. This article discusses the types of immunosuppression and their infectious and noninfectious implications. Key points of the most commonly involved pathogens are mentioned. Finally, an approach to diagnosis and empiric therapy is discussed.

Viral infections in severely immunocompromised cancer patients

Immunocompromised cancer patients are susceptible to infection by many viral pathogens. The most serious morbidity results from active infection by members of the herpes virus family. Reactivation of latent virus occurs as a sequela of cytotoxic therapy and deficiency of cell-mediated immunity, especially cytotoxic responses, the major host protective defense. Herpes simplex virus and varicella zoster virus infections are problematic in patients with all types of cancer; cytomegalovirus infections cause life-threatening morbidity in bone marrow transplant patients. Several antiviral agents are highly active against these pathogens and different strategies of using them have resulted in reduced morbidity and mortality. Ultimately, the resolution of these infections is dependent on the control of the malignancy and the ability of the patient to mount an adequate immune response.

Therapeutic use of ganciclovir for invasive cytomegalovirus infection in cadaveric renal allograft recipients

Between November 1987 and September 1989, 419 cadaveric renal transplants were performed at our university. Of the patients 36 (8.6%) had invasive cytomegalovirus infection documented by gastric or duodenal mucosal biopsy in 23 (64%), bronchoalveolar lavage in 12 (33%), allograft biopsy or nephrectomy specimen in 5 (14%) and/or liver biopsy in 1 (3%). Cytomegalovirus severity was defined as mild in 27 patients, moderate in 6 and severe in 3. Ganciclovir [9-(1,3-dihydroxy-2-propoxymethyl)-guanine] was begun once the diagnosis was confirmed by histology or culture at a median of 56 days from transplantation (range 28 to 133 days). Duration of ganciclovir therapy was a minimum of 7 days or until fever was absent for 5 consecutive days (mean 12.2 +/- 3.5 days, range 4 to 21). Ganciclovir was well tolerated and side effects were limited to de novo neutropenia (7 patients), thrombocytopenia (2) and rash (1). Initial clinical improvement was observed in all patients. Two patients had recurrent cytomegalovirus infections that responded to a second course of ganciclovir. The 1-year actuarial patient survival was 100%. At a mean followup of 12.7 +/- 6.2 months 19 patients retained allograft function with a mean serum creatinine of 2.5 mg./dl. (range 1.2 to 4.6). Ganciclovir appears to be a safe and effective drug for the treatment of tissue invasive cytomegalovirus infection in cadaver renal transplant recipients. Prompt institution of this drug at diagnosis of invasive cytomegalovirus may lower the mortality rate formerly associated with this disease.

Foscarnet for treatment of cytomegalovirus infections in bone marrow transplant recipients

42 episodes of verified or clinically suspected cytomegalovirus (CMV) infection in 40 bone marrow transplant (BMT) recipients were treated with foscarnet (trisodium phosphonophormate hexahydrate). CMV infection was verified in 31/42 treatment episodes. Symptoms treated were pneumonia (n = 17), pancytopenia with or without fever (n = 12), enteritis (n = 5), fever (n = 4), encephalitis (n = 2), retinitis (n = 1) and hepatitis (n = 1). Foscarnet was given as a continuous intravenous infusion. Side-effects observed were increase in serum creatinine (38%), decrease in serum calcium (19%), increase in serum bilirubin (12%), decrease in hemoglobin concentration (7%), increase in serum calcium (5%), increase in serum transaminase (5%), hypophosphatemia (2%) and tremor (2%). CMV was eradicated from blood and/or urine in 11/25 (44%) of assessable treatment episodes with infection verified by isolation. Overall clinical improvements including eradication of CMV, afebrility and/or improvements in laboratory abnormalities were seen in 14/31 (45%) episodes of verified infection. All 15 patients with CMV interstitial pneumonia (CMV IP) died. We conclude that foscarnet is nephrotoxic but otherwise well tolerated with moderate clinical and virostatic effects on CMV infection. The effect on CMV IP is discouraging.

Early treatment with ganciclovir to prevent cytomegalovirus disease after allogeneic bone marrow transplantation

BACKGROUND

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after allogeneic bone marrow transplantation. We conducted a controlled trial of ganciclovir for the early treatment of CMV infection in asymptomatic recipients of bone marrow transplants whose surveillance cultures for CMV became positive.

METHODS

Bone marrow--allograft recipients who were seropositive for CMV antibodies or who received seropositive marrow were screened for CMV excretion by culture of throat swabs, blood, urine, or bronchoalveolar-lavage fluid. In this double-blind trial, 72 patients who had marrow engraftment and were excreting virus were randomly assigned to receive either placebo or ganciclovir (5 mg per kilogram of body weight twice a day for one week, followed by 5 mg per kilogram per day) for the first 100 days after transplantation. Patients were followed for the development of biopsy-confirmed CMV disease, ganciclovir-related toxicity, and survival.

RESULTS

Between assignment to the study drug and day 100 after transplantation, CMV disease developed in only 1 of the 37 patients assigned to receive ganciclovir (3 percent), but in 15 of the 35 patients assigned to receive placebo (43 percent, P less than 0.00001). The ganciclovir recipients had rapid suppression of virus excretion; 85 percent had negative cultures after one week of treatment, as compared with 44 percent of the placebo group (P = 0.001). The principal toxic reaction was neutropenia; 11 ganciclovir recipients had an absolute neutrophil count below 0.75 x 10(9) per liter, as compared with 3 placebo recipients (P = 0.052). Treatment was discontinued in 11 ganciclovir recipients and 1 placebo recipient because of neutropenia (P = 0.003). After treatment was stopped, the neutrophil count recovered in all patients. Overall survival was significantly greater in the ganciclovir group than in the placebo group both 100 days and 180 days after transplantation (P = 0.041 and 0.027, respectively).

CONCLUSIONS

Early treatment with ganciclovir in patients with positive surveillance cultures reduces the incidence of CMV disease and improves survival after allogeneic bone marrow transplantation.

Combined antiviral effects of paired nucleosides against guinea pig cytomegalovirus replication in vitro

Several promising antiviral nucleosides have been tested in paired combinations against guinea pig cytomegalovirus (GPCMV) replication in guinea pig embryo (GPE) cells by plaque reduction assay; these are [9-(2-hydroxy-1-3-2-dioxaphosphorinan-5-yl)oxymethyl]-guanin e P-oxide (2'nor-cGMP, compound 164), [4-amino-5-bromo-7-(2-hydroxyethoxymethyl)-pyrrolo(2,3-d)pyrimidine] (compound 102), (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), 9-(2-hydroxyethoxymethyl)-guanine (acyclovir, ACV) and 3'-azido-3'-deoxythymidine (zidovudine, AZT). Various degrees of interactions were observed; i.e. synergistic reactions were noted in the presence of compound 164/compound 102 and compound 164/DHPG combinations at all concentrations tested. HPMPC/DHPG combinations were synergistic at relatively lower concentrations of DHPG, but became antagonistic as the concentration of DHPG increased. Combinations of compound 164/ACV and DHPG/AZT were antagonistic.

A multivariate analysis of risk factors for cytomegalovirus infection in liver-transplant recipients

Thirty-three consecutive liver-transplant recipients were prospectively studied over a 37-mo period for evidence of cytomegalovirus infection. Sixteen (48%) episodes of cytomegalovirus infection were identified; 9 were primary infections and 7 were recurrent infections. Beginning with patient 8, gamma-globulin prophylaxis was routinely administered to most patients. Twelve potential risk factors for cytomegalovirus infection were evaluated and included pretransplant cytomegalovirus serological status of donor and recipient; recipient's age, sex, race, and liver disease; number and type of blood products transfused; type and intensity of immunosuppression; and occurrence of rejection. The Cox proportional hazards model identified positive donor cytomegalovirus serology as the single most important risk factor for subsequent development of cytomegalovirus infection, regardless of recipient cytomegalovirus serological status. In addition, use of gamma-globulin prophylaxis seemed to be protective against the occurrence of disseminated cytomegalovirus disease.

Cytomegalovirus infection after organ transplantation: an update with special emphasis on renal transplantation

Cytomegalovirus infections are still the most important infectious complications after organ transplantation. Besides historical notes this review will deal with new aspects concerning the epidemiology of the CMV, diagnostic modalities of CMV infection, the delicate counterbalance between the immune system and the CMV, as well as the symptomatology of this infection. Furthermore, aspects like prophylaxis and new, promising therapeutic regimes for treatment of infection will be dealt with. Although this update is applicable for all types of solid organ transplantation, emphasis will be on renal transplantation.

Effect of 2'-nor-cyclic GMP against guinea pig cytomegalovirus infection

Cyclic phosphate derivative of DHPG, 2'-nor-cGMP [9-[(2-hydroxy-1,3,2-dioxaphosphorinan-5-yl)oxymethyl]-guani ne phosphate-oxide] was evaluated for activity against guinea pig cytomegalovirus (GPCMV) infection in cultured guinea pig embryo cells and in guinea pigs. By virus yield reduction and plaque reduction assays, 2'-nor-cGMP was demonstrated to be 15- to 20-fold more potent against GPCMV infection than its parental drug DHPG. The selectivity index of 2-nor-cGMP was 110, which was 10-fold higher than that of DHPG. In cultured cells, 2'-nor-cGMP attained maximal antiviral activity when added to the cells within 12 h postinfection. In the studies on GPCMV infection in guinea pigs, 2'-nor-cGMP administered subcutaneously once daily (5 mg/kg per day) for 8 days, starting 24 after virus inoculation, significantly suppressed GPCMV infectivity titers in the blood, spleen, lung, and salivary gland during acute infection (10 days postinfection) as compared with sham-treated infected animals. A greater reduction of GPCMV infectivity titers in the salivary gland was noted during chronic infection (i.e., 24 days postinfection). Clinically, splenomegaly and peripheral lymphocytosis were significantly modified as compared with the sham-treated animals (P less than 0.05). The drug, administered at this dosage, was reasonably tolerated by the guinea pigs and showed clinical benefit.

Effect of natural human interferon-beta on the replication of human cytomegalovirus

The antiviral effect of natural human interferon-beta (HuIFN-beta) against human cytomegalovirus (CMV) was evaluated in human embryonic lung fibroblasts (HEL). Natural HuIFN-beta, like other HuIFNs, inhibited the replication of CMV. Pretreatment of the cells with natural HuIFN-beta inhibited the appearance of immediate-early antigen (IEA) or pre-early nuclear antigen (PENA) as well as the production of infectious CMV. After a single treatment with natural HuIFN-beta, intracellular 2', 5'-oligoadenylate (2-5A) synthetase activity was induced and maintained at a high level for several days. The anti-CMV effect of natural HuIFN-beta correlated with the intracellular 2-5A synthetase activity.

Treatment of persistent active herpesvirus infections

All human herpesviruses cause chronic infections in which latent virus is periodically reactivated. Persistently active infections are uncommon, however, and occur exclusively in individuals whose immune systems fail to control virus multiplication and spread. This paper summarizes the management of these unusual infections.

Seronegative blood products prevent primary cytomegalovirus infection after bone marrow transplantation

Seventy one patients underwent bone marrow transplantation for aplastic anaemia or haematological malignancy, 39 as allografts and 32 as autografts. All patients who were seronegative to cytomegalovirus received blood product support exclusively from seronegative community blood donors; seropositive patients received unscreened products. In no patients was there any attempt to reduce cytomegalovirus (CMV) infection by giving prophylaxis with immunoglobulin, and granulocyte transfusions were not given. The incidence of cytomegalovirus infection in the seronegative recipients (22 allograft, 15 autograft) was 0%; in the seropositive recipients 16 (63%) in allografts and 17 (18%) in autografts. These results suggest that provision of exclusively seronegative blood products is an important contribution for seronegative transplant recipients, but make little impact in autologous transplantation where the incidence of infection is low.

Acyclovir for prevention of cytomegalovirus infection and disease after allogeneic marrow transplantation

Patients undergoing allogeneic bone marrow transplantation who are seropositive for cytomegalovirus are vulnerable to serious cytomegalovirus infection, presumably because of reactivation of latent endogenous virus and severe immunosuppression. We administered intravenous acyclovir from 5 days before to 30 days after allogeneic marrow transplantation for hematologic neoplasms in an effort to prevent cytomegalovirus infection and disease in patients seropositive for cytomegalovirus before transplantation. Eighty-six patients seropositive for both cytomegalovirus and herpes simplex virus before transplantation received acyclovir, whereas 65 patients seropositive only for cytomegalovirus served as controls (acyclovir is the standard prophylactic agent against herpes simplex virus in this setting). The probability that cytomegalovirus infection would develop within the first 100 days after transplantation was 0.70 among acyclovir recipients and 0.87 among control patients at medians of 62 and 40 days after transplantation, respectively (P = 0.0001 by log-rank test). Invasive cytomegalovirus disease developed in 19 acyclovir recipients (22 percent) and 25 control patients (38 percent) (P = 0.008). Survival within the first 100 days after transplantation was better among acyclovir recipients (P = 0.002). Acyclovir prophylaxis was associated with a relative risk of 0.5 or less for the development of cytomegalovirus infection or disease or for death within the first 100 days after transplantation (P less than or equal to 0.04), in proportional-hazards regression analysis. We conclude that prophylaxis with intravenous acyclovir significantly reduced the risk of both cytomegalovirus infection and cytomegalovirus disease in seropositive patients after allogeneic bone marrow transplantation and that it was also associated with significantly improved survival.

Treatment of cytomegalovirus retinopathy with ganciclovir

Ganciclovir is an experimental antiviral drug with activity against human cytomegalovirus (CMV). Forty patients with acquired immune deficiency syndrome (AIDS) and CMV retinopathy were treated with ganciclovir on a compassionate protocol basis. Initial treatment doses ranged from 5.0 to 14.0 mg/kg/day for 9 to 26 days. Signs of drug response were a halt to enlargement of lesions, decreased opacification of retinal tissue, and resolution of hemorrhage and vasculitis. Complete response was seen in 88% of patients and incomplete response was seen in 9%. Vision improved or remained stable in 88% of patients. Initial treatment did not eradicate live virus from the eye. To prevent reactivation of disease, 26 patients received low-dose maintenance therapy ranging from 1.5 to 7.5 mg/kg/day, once or twice daily, 3 to 7 days per week. Reactivation of disease developed for unknown reasons in 50% of patients on continuous, uninterrupted maintenance therapy for longer than 3 weeks. Reversible neutropenia, requiring cessation of treatment, developed in 30% of patients on initial treatment and in 38% of patients on maintenance therapy. Rhegmatogenous retinal detachment was a late complication in seven patients. By reducing or delaying visual loss, ganciclovir appears to be useful in the management of CMV retinopathy in patients with AIDS.

Treatment of cytomegalovirus pneumonitis with foscarnet (trisodium phosphonoformate) in patients with AIDS

Foscarnet was administered to eight AIDS patients for suspected cytomegalovirus (CMV) pneumonitis as a continuous intravenous infusion for a minimum of 8 days. All the patients improved, three showing complete resolution of symptoms. Evidence of CMV infection from bronchoalveolar lavage samples was lacking in two patients. Adverse drug experiences consisted of thrombophlebitis, transient decreases in haemoglobin concentration, and reversible rises in serum creatinine levels.

Pathologic features of cytomegalovirus retinopathy after treatment with the antiviral agent ganciclovir

Ganciclovir is a new antiviral compound (also called BW B759U, DHPG, BIOLF-62, and 2'NDG) that has been used for the treatment of cytomegalovirus (CMV) retinopathy in immunocompromised patients (bone marrow recipients or acquired immune deficiency syndrome [AIDS] victims). The authors studied the eyes of three AIDS patients with CMV retinopathy who died while receiving ganciclovir chemotherapy. Gross, microscopic, and ultrastructural studies of these cases showed varying degrees of retinal scarring and active CMV lesions at the margins of the scars. CMV antigens were localized in cells at all layers of retina at the border of the lesions and in isolated cells in a perivascular location within histologically normal appearing retina. These areas probably represent sites of recrudescence when the drug is discontinued. In situ hybridization using a cloned complementary DNA (cDNA) probe of human CMV corroborated the immunocytologic localization of the virus. Ultrastructural studies showed megalic syncytial cells containing mostly capsids exclusively in the cell nucleus. The cytoplasmic electron-dense membrane-bound bodies that have characterized untreated cases of CMV retinopathy were absent in the treated cases. An attempt to isolate CMV in tissue culture from the vitreous and retina of one of the cases yielded a negative result. Our results indicate that ganciclovir does not effectively eliminate CMV from the retina nor does it suppress expression of all viral genes. Ganciclovir appears to function by limiting viral DNA synthesis and subsequent packaging of viral DNA into infectious units, thereby acting as a virostatic chemotherapeutic agent.

Pyrrolo[2,3-d]pyrimidine nucleosides as inhibitors of human cytomegalovirus

Seven arabinosyl, 2'-deoxyribosyl, and ribosyl pyrrolo[2,3-d]pyrimidines were evaluated in vitro for activity against human cytomegalovirus and for cytotoxicity in primary and established cell lines of human origin. The parent ribosyl analogs exhibited little antiviral selectivity owing to high cytotoxicity. In contrast, ara-tubercidin, ara-toyocamycin, ara-sangivamycin, and deoxysangivamycin exhibited selectivity between antiviral effect (measured by plaque or titer reduction or both) and cytotoxicity (measured microscopically and by incorporation of radioactive precursors into DNA, RNA, and protein). The selectivity (in vitro therapeutic indexes) for these four compounds ranged from 2 to 40. The two sangivamycin analogs were the most potent and selective. Ara-sangivamycin, for example, inhibited virus replication 10(5)-fold at a concentration (10 microM) which produced only partial inhibition of cell growth and labeled precursor incorporation. The four arabinosyl and deoxyribosyl nucleosides appeared to act by inhibition of viral DNA synthesis as quantitated by DNA-DNA dot blot hybridization. These four analogs also were tested for activity against two strains of type 1 herpes simplex virus by a plaque reduction assay. Unexpectedly, all compounds inhibited herpes simplex virus to a lesser extent than human cytomegalovirus.

Molecular biology and immunology of cytomegalovirus

The application of modern biochemical techniques has led to a rapid improvement in our knowledge of the molecular biology of CMV. Several coding regions of the DNA genome have been identified with certainty and major virus-coded proteins have been given provisional names. The cascade expression of the CMV genome has been shown to be controlled by mechanisms similar to those found in other herpes viruses, together with novel post-transcriptional controls which remain to be defined. The control of CMV replication by the host involves both non-specific and specific defence mechanisms. The induction of natural killer cells and interferon early after CMV infection appears to be the most important aspects of the non-specific host defence against the virus. The cell-mediated immune response, in particular the generation of Tc cells against CMV early antigens, is probably the most important facet of the specific immune defence against CMV. When intact these defence mechanisms appear to be efficient in restricting viral replication; however, when such immunity is compromised, the balance rapidly swings in favour of the virus. As our understanding of the interaction between the host and the virus increases, it may be possible to redress the balance in such cases in favour of the host.

Vidarabine-associated encephalopathy and myoclonus

A 24-year-old man with disseminated herpes zoster, which occurred 9 months after bone marrow transplantation for chronic myeloid leukemia, developed encephalopathy and immobilizing myoclonus after 7 days of vidarabine treatment (10 mg/kg of body weight per day). Only mild hepatic dysfunction was a risk factor for a toxic reaction. After the vidarabine therapy was stopped, the symptoms worsened until treatment with hydration, large doses of chlordiazepoxide, and protective care gave symptomatic relief.

Treatment of serious cytomegalovirus infections with 9-(1,3-dihydroxy-2-propoxymethyl)guanine in patients with AIDS and other immunodeficiencies

The drug 9-(1,3-dihydroxy-2-propoxymethyl)-guanine (DHPG) was used to treat serious cytomegalovirus infections in 26 patients with underlying immunodeficiency (including 22 with the acquired immunodeficiency syndrome). In 17 of 22 patients in whom cytomegalovirus was virologically confirmed, clinical status improved or stabilized, although in 4 of them the status of some affected organs deteriorated or did not improve. Fourteen of 18 patients with adequate viral-culture data had clearing of cytomegalovirus from all cultured sites. Patients with cytomegalovirus pneumonia often responded poorly; four of seven died before completing 14 days of DHPG therapy. The condition of 11 of 13 patients with cytomegalovirus retinitis and 5 of 8 with gastrointestinal disease stabilized or improved. However, clinical and virologic relapses occurred in 11 of 14 patients (79 percent) when DHPG was discontinued. Neutropenia was the most frequent adverse reaction. We conclude that DHPG offers promise for the therapy of severe cytomegalovirus infections in some immunodeficient patients, but further study will be necessary to establish its efficacy and safety.

Early and late interstitial pneumonia following human bone marrow transplantation

Interstitial pneumonia is a major determinant of early and late morbidity and mortality following bone marrow transplantation. Among 952 patients receiving allogeneic marrow grafts in Seattle, 35% developed interstitial pneumonia within 100 days of transplant. Development of early cytomegalovirus (CMV) or idiopathic interstitial pneumonia was infrequent in patients with aplastic anemia prepared only with cyclophosphamide. Use of total body irradiation (TBI) in the transplant preparation, increasing patient age, pretransplant seropositivity for CMV antibody and post-transplant development of graft-versus-host disease (GVHD) all increased the risk of CMV pneumonia. Late interstitial pneumonia was studied in patients with chronic GVHD. Among 198 patients with extensive chronic GVHD, 31 episodes of interstitial pneumonia (seven idiopathic, six CMV, six pneumocystis, five miscellaneous and four unknown causes, and three varicella-zoster) were observed 3-24 months after transplant. In untreated patients with chronic GVHD, 15% developed late interstitial pneumonia. Patients with chronic GVHD who received prednisone +/- azathioprine as immunosuppressive therapy and trimethoprim sulfamethoxazole for infection prophylaxis had an 8% incidence of interstitial pneumonia. Patients with chronic GVHD given immunosuppressive treatment without trimethoprim sulfamethoxazole prophylaxis had a 28% incidence of interstitial pneumonia. Trimethoprim sulfamethoxazole significantly reduced the incidence of late interstitial pneumonia in patients with chronic GVHD (p = 0.001).

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.

Lung diseases after bone marrow transplantation. Results of a clinical, radiological, histological, immunological and lung function study

The case histories of 72 subsequently treated patients - 44 with acute leukemia, 10 with chronic myeloid leukemia, 16 with severe aplastic anemia and 2 with neuroblastoma - were analyzed after bone marrow transplantation (BMT) with respect to pulmonary diseases. Thirty-eight patients suffered from a total of 51 pulmonary complications, which led to death in 20. Of 13 patients, 3 died of bacterial pneumonia, all of them during granulocytopenia; 2 of 6 patients died of fungal pneumonia and 2 out of 3 of a mixed bacterial-mycotic infection. Adult respiratory distress syndrome (ARDS) led to death in 2 patients. A granulocyte count under 500/microliter correlated significantly (P less than 0.002) with the fatal outcome of bacterial, fungal and ARDS pneumonia as well as with bronchitis. Viral pneumonia led to death in 8 of 9 patients; in each there was a significant correlation (P less than 0.05) with graft-versus-host disease (GvHD). Patients with repeated episodes of pulmonary illness had significantly more chronic GvHD (P less than 0.05); several of these patients displayed a reduction in helper T cells and an increase in suppressor T cells in the peripheral blood. The natural killer (NK) cells were reduced and the percentage of activated NK cell level lay between 6% and 69%. B-cells were absent or deficient. These findings explain in part the absence of specific antibody reactivity. Five of these patients also contracted GvHD-associated obstructive bronchiolitis, which did not respond to therapy. Pulmonary infiltrates of unknown origin (including idiopathic interstitial pneumonia) occurred in 8 of the patients (11.1%), with a fatal outcome in 3 patients. Significant changes (P less than 0.05) in lung function after BMT appeared in the form of reduced vital capacity (VC) increased residual volume (RV) and an increase in RV expressed as the percentage of total lung capacity. Pulmonary diseases were the most common complication and cause of death in our patients after BMT.

Intravenous foscarnet for the treatment of severe cytomegalovirus infection in allograft recipients

Foscarnet, trisodium phosphonoformate, was administered intravenously to 6 immunosuppressed patients with life-threatening cytomegalovirus infection. Three of the patients were recipients of a kidney and 3 of a bone-marrow transplant. Favourable clinical responses were seen in 5 of the patients, 2 of whom were still in good health 5 and 8 months after the infection had cleared up. No toxic effect of the drug was detected. The results seem to justify further trials, in which foscarnet should be introduced at an earlier stage of the disease.

Inhibition of human cytomegalovirus by combined acyclovir and vidarabine

The inhibition of human cytomegalovirus (HCMV) isolates by acyclovir (ACV) and vidarabine (ara-A) was assessed by using an infectious-center plaque-reduction assay. When fixed concentrations of 4.5 micrograms of ACV and 250 ng of ara-A per ml were compared singly and in combination, the viral inhibition resulting from the ACV-ara-A combination was synergistic for three of four HCMV clinical isolates studied and additive for one HCMV isolate. An additional four HCMV strains obtained at postmortem examination from the lungs of bone marrow transplant patients were assessed for sensitivity to ACV-ara-A by using the dose required for 50% viral inhibition (ID50) as the endpoint. The mean ID50 of ACV for the four HCMV isolates was 12.3 micrograms/ml, whereas the mean ID50 of ara-A was 3.4 micrograms/ml. When 1 microgram of ara-A per ml (which yielded a mean plaque reduction of 23.6%) was combined with ACV, a mean of 5.2 micrograms of ACV per ml was required for 50% viral inhibition. The sum of the fractional inhibitory concentrations for each of the four HCMV isolates was less than 1, indicating synergy by the ACV-ara-A combination. Although DNA synthesis in growing human embryonic lung fibroblast (HEL) cells, as determined by [3H]thymidine incorporation, was diminished to 61% of that in untreated control cells when 22.5 micrograms of ACV and 1 microgram of ara-A per ml were used, there was no additive inhibition of DNA synthesis when the two-drug combination was used. HEL cell growth remained at 97% of control cell growth at 72 h when concentrations as high as 45 micrograms of ACV combined with 1 microgram of ara-A per ml were used.

Prevention and treatment of cytomegalovirus infections with interferons and immune globulins

With the exception of congenitally-infected infants, cytomegalovirus infection is generally benign in persons with normal host defenses. In contrast, among immunosuppressed patients, these infections may be severe and sometimes fatal. Treatment of cytomegalovirus infection with presently available antiviral agents including interferons has not been successful. Prevention of infection has been successful in several circumstances, however. Cytomegalovirus is transmitted by blood products from seropositive donors, and screening to remove seropositive blood products or freezing to destroy leukocytes has been effective amont neonates, cardiac transplant patients and renal dialysis patients. An alternative approach used among marrow transplant patients is passive immunization of seronegative patients with plasma or globulins with high antibody titers against cytomegalovirus. Alpha interferon given prophylactically has been effective in delaying virus reactivation and reducing the severity of infection among seropositive renal transplant patients. All of these approaches, as well as the continued development of more effective antiviral agents, will be needed for control of cytomegalovirus infection.

Pulmonary complications of bone marrow transplantation

Bone marrow transplantation (BMT) for hematologic disorders is potentially curative in selected persons. These patients may be immunocompromised for months after engraftment as a consequence of chemotherapy, irradiation, acute and chronic graft-vs-host disease (GVHD), and maturing recipient marrow. Pulmonary complications commonly occur during the early and late periods after BMT and are associated with significant morbidity and mortality. The leading early-onset complication is interstitial pneumonitis, most commonly associated with cytomegalovirus infection but also related to possible toxicities from chemotherapy and irradiation. Major late-onset problems include bacterial sinopulmonary infections and obstructive airway disease thought to be associated with chronic GVHD. The exact mechanisms of lung injury are probably quite complex, and unfortunately, often cause irreversible pulmonary disease, even in the patient who has had successful transplantation. Antimicrobial prophylaxis, modified chemotherapy and irradiation dosages, and antiviral immunization have been shown to reduce the incidence of early-onset pulmonary problems. Early recognition and treatment of late-onset problems will, it is hoped, minimize respiratory limitations.

Marrow transplant experience in children with acute lymphoblastic leukemia: an analysis of factors associated with survival, relapse, and graft-versus-host disease

One hundred fourteen children with acute lymphoblastic leukemia were treated with allogeneic marrow transplantation from HLA-identical siblings after conditioning with cyclophosphamide and total body irradiation. Methotrexate was given posttransplantation for prophylaxis of graft-versus-host disease. The minimum follow-up after transplantation was 2 years. Sixteen of 51 patients transplanted in marrow remission survive from 2.1 to 8.9 years (median 2.7), 13 in continuous remission, one in remission following testicular relapse, and two after marrow relapse. Sixty-three were transplanted in relapse and eight survived 3-10 years (median 5.7), five in continuous remission, and three in remission following testicular relapse. In a multivariate analysis, factors significantly related to increased survival were marrow remission at transplant (p less than 0.007) and chronic graft-versus-host disease (p less than 0.005). Factors associated with increased relapse were marrow relapse at transplant (p less than 0.002) and absence of significant graft-versus-host disease (p less than 0.004). The development of acute graft-versus-host disease was associated with high marrow cell doses (p less than 0.04). These data suggest that some children with acute lymphoblastic leukemia and a poor prognosis with conventional chemotherapy may be cured with marrow transplantation.

Prevention of cytomegalovirus infection by prophylaxis with an intravenous, hyperimmune, native, unmodified cytomegalovirus globulin. Randomized trial in bone marrow transplant recipients

We have completed a randomized trial to evaluate the safety and effectiveness of hyperimmune cytomegalovirus intravenous human globulin in prevention of cytomegalovirus infection and related problems in bone marrow transplant recipients. Prophylactic intravenous administration of this native, intact, hyperimmune, cytomegalovirus IgG, at a dose of 200 mg/kg 25, 50, and 75 days following transplant resulted in complete protection against cytomegalovirus infection during the 120 days covered by the treatment (p = 0.009). There was no interstitial pneumonia or mortality in the group receiving the hyperimmune IgG. This is significant at the p = 0.014 when compared with the supporting treatment control group. In bone marrow transplant recipients, prophylaxis with a total dosage of 0.6 g/kg of an intravenous hyperimmune cytomegalovirus globulin was safe and afforded effective protection against cytomegalovirus infection and interstitial pneumonia in this high-risk population.

Limitations of current antimicrobial therapy in the immunosuppressed host: looking at both sides of the coin

During the last twenty years there have been considerable advances in the antimicrobial management of the immunosuppressed host. These include the development of antibiotics with broad-spectrum and high bactericidal activity along with the appreciation of the importance of promptly initiating empiric antibiotic therapy when the granulocytopenic patient becomes febrile and continuing them (in some cases with empiric antifungal therapy) until the resolution of granulocytopenia. Nonetheless, infection still remains a major cause of death in compromised hosts and a number of limitations of therapy persist. Included are a limited repertoire of drugs active against fungi (particularly Aspergillus) as well as certain viruses (for example, cytomegalovirus) and the inability to eradicate certain sites of infection (for example, Pseudomonas pneumonia) even with effective agents. Current investigations are focused on developing new antimicrobial agents as well as methods to improve the altered host defenses of immunosuppressed patients, both as adjuvants to therapy and, eventually, as a means to prevent infectious complications.

Intravenous immunoglobulin for modification of cytomegalovirus infections associated with bone marrow transplantation. Preliminary results of a controlled trial

The effects of immune globulin intravenous, 5 percent in 10 percent maltose, on cytomegalovirus infection and interstitial pneumonia in bone marrow transplants were evaluated in a randomized controlled trial. Eighteen patients were given weekly doses (20 cc/kg) of intravenous immunoglobulin before and after transplantation, and 18 patients were controls. The incidence of cytomegalovirus infection was similar in the control and intravenous immunoglobulin-treated groups, but symptomatic cytomegalovirus infection (eight of 18 versus three of 18, p = 0.14) and interstitial pneumonia (10 of 18 versus four of 18, p = 0.08) occurred less frequently in the group receiving intravenous immunoglobulin. Cytomegalovirus pneumonia developed in eight control patients and in three patients receiving intravenous immunoglobulin (p = 0.14), whereas two control patients and one patient receiving intravenous immunoglobulin experienced idiopathic interstitial pneumonia. These preliminary results suggest that intravenous immunoglobulin can modify the severity of cytomegalovirus infection and prevent interstitial pneumonia in bone marrow transplant recipients.

Prevention and treatment of cytomegalovirus infections with interferons and immune globulins

With the exception of congenitally-infected infants, cytomegalovirus infection is generally benign in persons with normal host defenses. In contrast, among immunosuppressed patients, these infections may be severe and sometimes fatal. Treatment of cytomegalovirus infection with presently available antiviral agents including interferons has not been successful. Prevention of infection has been successful in several circumstances, however. Cytomegalovirus is transmitted by blood products from seropositive donors, and screening to remove seropositive blood products or freezing to destroy leukocytes has been effective among neonates, cardiac transplant patients and renal dialysis patients. An alternative approach used among marrow transplant patients is passive immunization of seronegative patients with plasma or globulins with high antibody titers against cytomegalovirus. Alpha interferon given prophylactically has been effective in delaying virus reactivation and reducing the severity of infection among seropositive renal transplant patients. All of these approaches, as well as the continued development of more effective antiviral agents, will be needed for control of cytomegalovirus infection.