Influenza A pneumonitis following treatment of acute cardiac allograft rejection with murine monoclonal anti-CD3 antibody (OKT3)

Influenza H1N1 infection in immunocompromised host: A concise review

Influenza A (H1N1) infection has a propensity to infect an immunocompromised host (ICH). These patients experience more severe manifestations and related complications with increased mortality. Influenza A (H1N1) infection in ICH differs from non-ICH in terms of clinical features, range of complications, radiological features, treatment response, and outcome. Radiology may show higher number of lesions but with no or minimal corresponding clinical manifestations. Coinfection with streptococci, staphylococci, and Aspergillus further increases mortality. Antiviral resistance compounds the overall picture despite optimal regimen. Use of steroids is detrimental. Extracorporeal membrane oxygenation (ECMO) is usually avoided in ICH. However, ICH groups with influenza A (H1N1) infection complicated by acute respiratory distress syndrome who have received ECMO have recorded mortality up to 61%. Nevertheless, evidence-based recommendation on use of ECMO in ICH is lacking. Annual inactivated influenza vaccine is recommended for most ICH groups with a few exceptions and for their close contacts. Hygiene measures greatly contribute to reducing disease burden. High index of suspicion for influenza A (H1N1) infection in ICH, early antiviral therapy, and treatment of coinfection is recommended. With the threat of transmission of resistant viral strains from ICH to the community, apart from treatment, preventive measures such as vaccination and hygienic practices have a significant role. Through this review, we have attempted to identify clinical and radiological peculiarities in ICH with influenza A (H1N1) infection, treatment guidelines, and prognostic factors. Influenza A (H1N1) infection in ICH may remain clinically silent or mild.

The natural history of influenza infection in the severely immunocompromised vs nonimmunocompromised hosts

Introduction. Medical advances have led to an increase in the world's population of immunosuppressed individuals. The most severely immunocompromised patients are those who have been diagnosed with a hematologic malignancy, solid organ tumor, or who have other conditions that require immunosuppressive therapies and/or solid organ or stem cell transplants.

Materials and methods. Medically attended patients with a positive clinical diagnosis of influenza were recruited prospectively and clinically evaluated. Nasal washes and serum were collected. Evaluation of viral shedding, nasal and serum cytokines, clinical illness, and clinical outcomes were performed to compare severely immunocompromised individuals to nonimmunocompromised individuals with influenza infection.

Results. Immunocompromised patients with influenza had more severe disease/complications, longer viral shedding, and more antiviral resistance while demonstrating less clinical symptoms and signs on clinical assessment.

Conclusions. Immunocompromised patients are at risk for more severe or complicated influenza induced disease, which may be difficult to prevent with existing vaccines and antiviral treatments. Specific issues to consider when managing a severely immunocompromised host include the development of asymptomatic shedding, multi-drug resistance during prolonged antiviral therapy, and the potential high risk of pulmonary involvement.

Clinical trials registration, ClinicalTrials.gov identifier NCT00533182.

Respiratory syncytial virus pneumonia treated with lower-dose palivizumab in a heart transplant recipient

Respiratory syncytial virus (RSV) is an important community-acquired pathogen that can cause significant morbidity and mortality in patients who have compromised pulmonary function, are elderly, or are immunosuppressed. This paper describes a 70-year-old man with a remote history of heart transplantation who presented with signs and symptoms of pneumonia. Chest computed tomography (CT) imaging demonstrated new patchy ground glass infiltrates throughout the upper and lower lobes of the left lung, and the RSV direct fluorescence antibody (DFA) was positive. The patient received aerosolized ribavirin, one dose of intravenous immunoglobulin, and one dose of palivizumab. After two months of followup, the patient had improved infiltrates on chest CT, improved pulmonary function testing, and no evidence of graft rejection or dysfunction. There are few data on RSV infections in heart transplant patients, but this case highlights the importance of considering this potentially serious infection and introduces a novel method of treatment.

A prospective, comparative study of the immune response to inactivated influenza vaccine in pediatric liver transplant recipients and their healthy siblings

BACKGROUND

Annual influenza vaccination is routinely recommended for pediatric solid organ transplant recipients. However, there are limited data defining the immune response to the inactivated vaccine in this population.

METHODS

This prospective study compared the humoral and cell-mediated immune responses to the trivalent subvirion influenza vaccine in pediatric liver transplant recipients with those in their healthy siblings. All subjects received inactivated influenza vaccine. Hemagglutination inhibition and interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot assays for New Caledonia and Shanghai strains were performed at baseline, after each vaccine dose, and 3 months after the series. Seroconversion was defined as a 4-fold increase in antibody titers; seroprotection was defined as an antibody titer > or =1:40. An increase in the number of T cells secreting IFN-gamma was considered to be a positive enzyme-linked immunosorbent spot response.

RESULTS

After 1 dose of vaccine, transplant recipients achieved rates of antibody seroprotection and seroconversion that were similar to those achieved by their healthy siblings. However, for both influenza strains, IFN-gamma responses by enzyme-linked immunosorbent spot were significantly attenuated in transplant recipients after 2 doses of vaccine. No cases of influenza or vaccine-related serious adverse events were documented in the study.

CONCLUSIONS

The diminished cell-mediated immune response to influenza vaccination that was observed in pediatric liver transplant recipients suggests that the current vaccine strategy may not provide optimal protection. Because of concerns regarding potential emergence of more virulent influenza strains, further studies are warranted to determine if IFN-gamma responses are predictive of efficacy and to identify the optimal vaccination strategy to protect populations with a high risk of infection.

The pathogenesis and management of influenza virus infection in organ transplant recipients

Infection with influenza viruses poses specific problems in adult and pediatric organ transplant recipients, including a higher rate of pulmonary and extra-pulmonary complications. Also, data suggest that influenza is associated with acute cellular rejection and chronic allograft dysfunction. The main strategy of influenza prevention has been influenza immunization in order to stimulate local and systemic antibodies. However, studies have shown that antibody response to inactivated influenza vaccine is decreased in all groups of organ transplant recipients. A live attenuated influenza virus vaccine is nearing approval in the United States. However, studies are needed in organ transplant recipients to determine whether the live attenuated influenza virus vaccine can enable these patients to mount a protective immune response and what degree of protection or amelioration of illness is provided by such vaccine. It is also important to verify the safety of this vaccine in organ transplant recipients because live virus may cause severe disease in these patients. Therefore, other modalities of prevention against influenza, such as chemoprophylaxis with antiviral drugs, should be considered in this patient population. The current review provides an overview of the incidence, clinical manifestations, and strategies for the prevention and management of influenza in organ transplant recipients.

Pulmonary complications in cardiac transplant recipients

BACKGROUND

The incidence of pulmonary complications in heart transplant recipients has not been extensively studied. We report pulmonary complications in 159 consecutive adult orthotopic heart transplantations (OHTs) performed in 157 patients.

MATERIALS AND METHODS

Retrospective review of medical records.

RESULTS

Forty-seven of 159 recipients (29.9%) had 81 pulmonary complications. Pneumonia was the most common (n = 27), followed by bronchitis (n = 15), pleural effusion (n = 10), pneumothorax (n = 7), prolonged respiratory failure requiring tracheotomy (n = 7), and obstructive sleep apnea syndrome (n = 6). All patients with late-onset (> 6 months after transplantation) community-acquired bacterial pneumonia presented with fever, cough, and a new lobar consolidation on the chest radiograph, and responded promptly to empiric antibiotics without undergoing an invasive diagnostic procedure. In contrast, early-onset nosocomial bacterial pneumonias carried a 33.3% mortality rate. A positive tuberculin skin test result was associated with a significantly higher rate of pulmonary complications (62.5% vs 26.8%, p = 0.007). Lung cancer and posttransplant lymphoproliferative disorder (PTLD) developed exclusively in 6 of the 61 patients (8.1%) who received induction immunosuppression with murine monoclonal antibody (OKT3).

CONCLUSION

Pulmonary complications are common following heart transplantation, occurring in 29.9% of recipients, and are attributed to pneumonia of primarily bacterial origin in one half of cases. Late-onset community-acquired pneumonia carried an excellent prognosis following empiric antibiotic therapy, suggesting that in the appropriate clinical setting invasive diagnostic procedures are unnecessary. Analogous to reports in other solid-organ transplant recipients, induction therapy with OKT3 was associated with an increased incidence of lung cancer and PTLD. Overall, the development of pulmonary complications after OHT has prognostic significance given the higher mortality in this subset of patients.

Vaccines for transplant recipients

Immune dysregulation and immunosuppression regimens impact on the ability of transplant recipients to respond to immunizations. The distinct challenges of immunizations to benefit stem cell transplant recipients and solid organ transplant recipients are discussed separately. Recommended vaccines for stem cell transplant recipients and solid organ transplant candidates are suggested. New approaches to consider to enhance immune responses of transplant recipients are discussed.

Immunization of pediatric solid organ transplant candidates and recipients

Organ transplantation has evolved from an experimental procedure to an accepted treatment for otherwise irreversible or congenital disorders. The immunosuppression necessary to prevent rejection enhances the severity of many infectious diseases and may potentially attenuate the response to vaccines designed to prevent disease. In spite of the frequency and severity of infectious diseases in organ transplant recipients, many children are not fully vaccinated before transplantation. The safety and efficacy of many of the currently available vaccines for solid organ transplant recipients have not been evaluated. We review the currently available data on immunization safety and efficacy, discuss experimental vaccines, and outline strategies to avoid vaccine-preventable diseases in pediatric organ transplant recipients.

Differential immune response to influenza and pneumococcal vaccination in immunosuppressed patients after heart transplantation

INTRODUCTION

Patients after solid organ transplantation are at an increased risk for microbial infections. Due to therapeutic immunosuppression, the response to active immunizations may be reduced. The serological efficacy of pneumococcal and influenza vaccination was studied in heart transplant recipients.

PATIENTS AND METHODS

Sixteen patients over 1 year after heart transplantation and control patients were immunized with a 23-valent pneumococcal vaccine and a triple-split influenza vaccine. Pre- and postvaccinal antibody titers were serologically determined, including quantitation of specific antibodies against nine pneumococcal serotypes.

RESULTS

Both vaccines were well tolerated without systemic reactions or infectious complications. Median postvaccinal pneumococcal antibody titers in the transplant patients were comparable to controls (5513 U/ml, range: 694-41007, vs. 5490 U/ml, range: 1088-38042; P=NS); vaccination was successful in 23/23 (100%) of controls and in 15/16 (94% plus 1 borderline positive case) of the transplant recipients. Specific antibody titers were similar for eight of nine serotypes; only the immune response against serotype 3 was reduced after transplantation. The efficacy of influenza vaccination was significantly impaired in transplant patients against all three virus strains (62% vs. 97%, P<0.01/50% vs. 94%, P<0.001/37% vs. 80%, P<0.01), but 9/16 (56%) of patients still showed a sufficient immune response to two out of three virus strains. No clinical or demographic predictors of successful vaccination could be established.

CONCLUSIONS

Pneumococcal vaccination under cyclosporine-based immunosuppression after heart transplantation is safe and equally effective as in healthy controls. In contrast, the immune response to influenza vaccination is significantly reduced, although not completely abolished. This differential response might be accounted for by T cell-independent antibody production against polysaccharide antigens contained in the pneumococcal vaccine.

Prevention and treatment of influenza in immunocompromised patients

Influenza A and B viruses cause serious, sometimes fatal, disease in immunocompromised patients, particularly bone marrow and solid organ transplant recipients. Protracted disease has also been recognized in certain oncology and HIV-infected patients. Currently available inactivated vaccines are variably immunogenic in such groups. Poor humoral immune responses are seen within 2 years of bone marrow transplantation, often following solid organ transplantation, and commonly in patients with advanced HIV infection. Oral amantadine and rimantadine are useful for prophylaxis and treatment of influenza A virus infections, but their efficacy, particularly in treatment of severe disease, has not been rigorously established in immunocompromised hosts. Case reports document the emergence of drug-resistant variants and prolonged viral shedding in some patients. Aerosol and intravenous ribavirin has been used to treat severe influenza in small numbers of immunosuppressed patients, but the efficacy of ribavirin by either route has not been established in such patients. The neuraminidase inhibitor GG167 is active in experimental influenza but requires topical application to the respiratory tract and has had limited clinical study in natural influenza. More effective interventions for serious influenza infections will likely require combinations of antiviral drugs.