Impaired anti-pneumococcal polysaccharide antibody production and invasive pneumococcal infection following heart transplantation

Post-Transplantation Seroprotection Rates in Liver, Lung, and Heart Transplant Recipients Vaccinated Pre-Transplantation against Hepatitis B Virus and Invasive Pneumococcal Disease

Vaccination before solid organ transplantation is recommended since post-transplantation immunosuppression is known to impair vaccine responses. However, little is known about post-transplantation seroprotection rates in organ transplant recipients vaccinated pre-transplantation. We aimed to investigate the proportion of transplant recipients vaccinated against hepatitis B virus (HBV) and invasive pneumococcal disease (IPD) pre-transplantation at the time of listing for transplantation with post-transplantation seroprotection. We included 136 solid organ transplant (SOT) recipients vaccinated at the time of listing for transplantation. We investigated post-transplantation antibody concentrations against HBV and IPD. Established antibody thresholds were used to define seroprotection. The proportions of SOT recipients with post-transplantation seroprotection were 27.9% (n = 38) and 42.6% (n = 58) against HBV and IPD, respectively. Compared to completing HBV vaccination pre-transplantation, completing post-transplantation vaccination (adjusted odds ratio (aOR): 7.8, 95% CI: 2.5-24.5, p < 0.001) and incomplete vaccination (aOR: 6.3, 95% CI: 1.2-32.6, p = 0.028) were associated with non-response against HBV, after adjustment for confounders. Importantly, patients with seroprotection at the time of listing had lower odds of non-response against HBV (aOR: 0.04, 95% CI: 0.0-0.1, p < 0.001) and IPD (aOR: 0.3, 95% CI: 0.1-0.7, p = 0.007) compared to those without seroprotection. SOT recipients vaccinated pre-transplantation had low post-transplantation seroprotection rates against HBV and IPD. However, SOT recipients with seroprotection at the time of listing had lower odds of non-response, suggesting early vaccination should be a priority.

The Expanding Field of Secondary Antibody Deficiency: Causes, Diagnosis, and Management

Antibody deficiency or hypogammaglobulinemia can have primary or secondary etiologies. Primary antibody deficiency (PAD) is the result of intrinsic genetic defects, whereas secondary antibody deficiency may arise as a consequence of underlying conditions or medication use. On a global level, malnutrition, HIV, and malaria are major causes of secondary immunodeficiency. In this review we consider secondary antibody deficiency, for which common causes include hematological malignancies, such as chronic lymphocytic leukemia or multiple myeloma, and their treatment, protein-losing states, and side effects of a number of immunosuppressive agents and procedures involved in solid organ transplantation. Secondary antibody deficiency is not only much more common than PAD, but is also being increasingly recognized with the wider and more prolonged use of a growing list of agents targeting B cells. SAD may thus present to a broad range of specialties and is associated with an increased risk of infection. Early diagnosis and intervention is key to avoiding morbidity and mortality. Optimizing treatment requires careful clinical and laboratory assessment and may involve close monitoring of risk parameters, vaccination, antibiotic strategies, and in some patients, immunoglobulin replacement therapy (IgRT). This review discusses the rapidly evolving list of underlying causes of secondary antibody deficiency, specifically focusing on therapies targeting B cells, alongside recent advances in screening, biomarkers of risk for the development of secondary antibody deficiency, diagnosis, monitoring, and management.

Pneumococcal vaccination in adult solid organ transplant recipients: A review of current evidence

This narrative review summarizes the current literature relating to pneumococcal vaccination in adult solid organ transplant (SOT) recipients, who are at risk of invasive pneumococcal disease (IPD) with its attendant high morbidity and mortality. The effect of the pneumococcal polysaccharide vaccine has been examined in several small cohort studies in SOT recipients, most of which were kidney transplant recipients. The outcomes for these studies have been laboratory seroresponses or functional antibody titers. Overall, in most of these studies the transplant recipients were capable of generating measurable serological responses to pneumococcal vaccination but these responses were less than those of healthy controls. A mathematical model estimated the effectiveness of polysaccharide vaccination in SOT recipients to be one third less than those of patients with HIV. The evidence for the efficacy of the pneumococcal conjugate vaccine in SOT is based on a small number of randomized controlled trials in liver and kidney transplant recipients. These trials demonstrated that SOT recipients mounted a serological response following vaccination however there was no benefit to the use of prime boosting (conjugate vaccine followed by polysaccharide vaccine). Currently there are no randomized studies investigating the clinical protection rate against IPD after pneumococcal vaccination by either vaccine type or linked to vaccine titers or other responses against pneumococcus. Concerns that vaccination may increase the risk of adverse alloresponses such as rejection and generation of donor specific antibodies are not supported by studies examining this aspect of vaccine safety. Pneumococcal vaccination is a potentially important strategy to reduce IPD in SOT recipients and is associated with excellent safety. Current international recommendations are based on expert opinion from conflicting data, hence there is a clear need for further high-quality studies in this high-risk population examining optimal vaccination regimens. Such studies should focus on strategies to optimize functional immune responses.

Evaluation of humoral immunity profiles to identify heart recipients at risk for development of severe infections: A multicenter prospective study

BACKGROUND

New biomarkers are necessary to improve detection of the risk of infection in heart transplantation. We performed a multicenter study to evaluate humoral immunity profiles that could better enable us to identify heart recipients at risk of severe infections.

METHODS

We prospectively analyzed 170 adult heart recipients at 8 centers in Spain. Study points were before transplantation and 7 and 30 days after transplantation. Immune parameters included IgG, IgM, IgA and complement factors C3 and C4, and titers of specific antibody to pneumococcal polysaccharide antigens (anti-PPS) and to cytomegalovirus (CMV). To evaluate potential immunologic mechanisms leading to IgG hypogammaglobulinemia, before heart transplantation we assessed serum B-cell activating factor (BAFF) levels using enzyme-linked immunoassay. The clinical follow-up period lasted 6 months. Clinical outcome was need for intravenous anti-microbials for therapy of infection.

RESULTS

During follow-up, 53 patients (31.2%) developed at least 1 severe infection. We confirmed that IgG hypogammaglobulinemia at Day 7 (defined as IgG <600 mg/dl) is a risk factor for infection in general, bacterial infections in particular, and CMV disease. At Day 7 after transplantation, the combination of IgG <600 mg/dl + C3 <80 mg/dl was more strongly associated with the outcome (adjusted odds ratio 7.40; 95% confidence interval 1.48 to 37.03; p = 0.014). We found that quantification of anti-CMV antibody titers and lower anti-PPS antibody concentrations were independent predictors of CMV disease and bacterial infections, respectively. Higher pre-transplant BAFF levels were a risk factor of acute cellular rejection.

CONCLUSION

Early immunologic monitoring of humoral immunity profiles proved useful for the identification of heart recipients who are at risk of severe infection.

Pneumococcal immunization in immunocompromised hosts: where do we stand?

Immunocompromised patients are all at risk of invasive pneumococcal disease, of different degrees and timings. However, considerable progress in pneumococcal immunization over the last 30 years should benefit these patients. The 23-valent polysaccharide vaccine has been widely evaluated in these populations, but due to its low immunogenicity, its efficacy is sub-optimal, or even low. The principle of the conjugate vaccine is that, through the protein conjugation with the polysaccharide, the vaccine becomes more immunogenic, T-cell dependent, and thus providing a better early response and a boost effect. The 7-valent conjugate vaccine has been the first one to be evaluated in different immunocompromised populations. We review here the efficacy and safety of the different antipneumococcal vaccines in cancer, transplant and HIV-positive patients and propose a critical appraisal of the current guidelines.

Randomized, single blind, controlled trial to evaluate the prime-boost strategy for pneumococcal vaccination in renal transplant recipients

Renal transplant recipients are at increased risk of developing invasive pneumococcal diseases but may have poor response to the 23-valent pneumococcal polysaccharide vaccine (PPV). It may be possible to enhance immunogenicity by priming with 7-valent pneumococcal conjugate vaccine (7vPnC) and boosting with PPV 1 year later. In a randomized single-blind, controlled study, adult recipients of renal transplants received either 7nPVC or PPV followed by PPV 1 year later. The vaccine response was defined as 2-fold increase in antibody concentration from baseline and an absolute post-vaccination values ≥1 µg/ml. The primary endpoint was vaccine response of the primed group (7vPnC/PPV) compared with single PPV vaccination. Antibody concentrations for 10 serotypes were measured at baseline, 8 weeks after first vaccination, before second vaccination, and 8 weeks after second vaccination. Of 320 screened patients, 80 patients were randomized and 62 completed the study. Revaccination with PPV achieved no significant increase of immune response in the 7vPnC/PPV group compared with the single PPV recipients A response to at least 1 serotype was seen in 77.1% of patients who received 7vPnC and 93.1% of patients who received PPV (P = 0.046). After second vaccination response to at least 1 serotype was seen in 87.5% patients of 7vPnC/PPV group and 87.1% patients of PPV group (non significant p). The median number of serotypes eliciting a response was 3.5 (95% CI 2.5–4.5) in the 7vPnC/PPV group versus 5 (95% CI 3.9–6.1) in the PPV group (non-significant p). Immunogenicity of pneumococcal vaccination was not enhanced by the prime–boost strategy compared with vaccination with PPV alone. Administration of a single dose of PPV should continue to be the standard of care for adult recipients of renal transplants.

Trial Registration

EudraCT 2007-004590-25.

Immunogenicity of a combined schedule of 7-valent pneumococcal conjugate vaccine followed by a 23-valent polysaccharide vaccine in adult recipients of heart or lung transplants

A combined schedule of 7-valent pneumococcal conjugate vaccine (PCV7) followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) was evaluated retrospectively in 26 adult recipients of heart or lung transplants. PCV7 was immunogenic in these patients but there appeared to be no benefit from the additional PPV23 dose.

Infectious and non-infectious neurologic complications in heart transplant recipients

Neurologic complications are important causes of morbidity and mortality in heart transplant (HT) recipients. New immunomodulating agents have improved survival rates, although some have been associated with a high rate of neurologic complications (infectious and non-infectious). We conducted this study to analyze the frequency of these complications, before and after the use of daclizumab induction therapy. We reviewed all neurologic complications in our HT cohort, comparing infectious with non-infectious complications over 2 periods of time in which different induction therapies were used (316 patients with OKT3 or antithymocyte globulin from 1988 to 2002, and 68 patients with daclizumab from 2003 to 2006). Neurologic complications were found in 75/384 patients (19.5%) with a total of 78 episodes. Non-infectious complications accounted for 68% of the 78 episodes of neurologic complications. A total of 51 patients and 53 episodes were detailed as follows: 25 episodes of stroke (25 of 78 total episodes, 32%; 19 ischemic, 6 hemorrhagic); 7 neuropathies; 6 seizures; 4 episodes of transient ischemic attack (TIA); 3 anoxic encephalopathy; 2 each brachial plexus palsy and metabolic encephalopathy; and 1 each myoclonia, central nervous system (CNS) lymphoma, subdural hematoma, and Cotard syndrome. Mean time to presentation of stroke, TIA, and encephalopathy was 1 day (range, 1-19 d) posttransplant. Mortality rate among non-infectious complications was 12/53 (22.6%). Infectious complications accounted for 32% of the 78 total episodes. We found 25 episodes in 24 patients: 17 herpes zoster (median, 268 d after HT), 3 CNS aspergillosis (median, 90 d after HT), 1 CNS toxoplasmosis and tuberculosis (51 d after HT), 1 pneumococcal meningitis (402 d after HT), and 2 Listeria meningitis (median, 108 d after HT). The 3 patients with CNS aspergillosis died. The mortality rate among patients with infectious neurologic complications was 12% (42.8% if the CNS was involved). When we compared the OKT3-ATG and daclizumab groups, we found that the incidence of non-infectious complications was 15.1% vs. 7.3%, respectively, and the incidence of infectious complications was 7.5% vs. 1.4%, respectively. All but 1 opportunistic infection occurred in the OKT3-ATG time period. In conclusion, a wide variety of neurologic complications affected 19.5% of HT recipients. Non-infectious causes clearly predominated, but infections still accounted for 32% of the episodes. New monoclonal induction therapies have contributed to diminished CNS opportunistic infections in our program.

Community-acquired acute bacterial meningitis in the elderly in Turkey

This investigation aimed both to delineate the current status of community-acquired acute bacterial meningitis and to produce data on the interrelationships between clinical, laboratory and therapeutic parameters in the elderly. This retrospective cohort study was conducted in 28 Turkish institutions in 159 culture-positive patients over the age of 50 years. Streptococcus pneumoniae was the most common pathogen (69.2%), followed by Listeria monocytogenes (8.8%). For this reason, antilisterial antibiotics such as ampicillin or benzylpenicillin should be added to the therapeutic regimen. Pathogen-specific mortality did not vary between S. pneumoniae and L. monocytogenes. The overall mortality was 2.5% at the third day, 12.6% at the seventh day, 20.1% at the 14th day and 21.4% at the 21st day. The risk factors for fatality were increasing age, the presence of stupor, sepsis and inappropriate antibiotic administration. Cerebrospinal fluid (CSF) leukocyte counts and CSF/blood glucose ratios were lower in patients who died. Fever did not differ between survivors and fatal cases. The mean duration of antibiotic therapy in survivors was 16.3 +/- 6.4 days. One-fifth of the patients had complications, and in 5.7% of the patients sequelae persisted at follow-up.

Infectious complications associated with monoclonal antibodies and related small molecules

Biologics are increasingly becoming part of routine disease management. As more agents are developed, the challenge of keeping track of indications and side effects is growing. While biologics represent a milestone in targeted and specific therapy, they are not without drawbacks, and the judicious use of these "magic bullets" is essential if their full potential is to be realized. Infectious complications in particular are not an uncommon side effect of therapy, whether as a direct consequence of the agent or because of the underlying disease process. With this in mind, we have reviewed and summarized the risks of infection and the infectious disease-related complications for all FDA-approved monoclonal antibodies and some related small molecules, and we discuss the probable mechanisms involved in immunosuppression as well as recommendations for prophylaxis and treatment of specific disease entities.

[Infections of the central nervous system in the immuno-compromised]

Infections of the central nervous system (CNS) can be caused by a variety of pathogens, depending on whether the number and function of T-cells or monocytes are impaired (as in HIV patients) or whether the number and function of polymorphonuclear granulocytes are reduced or impaired, as typically seen in patients on immunosuppressive therapy, post transplantation, etc.. The first part of the chapter deals with CNS infections associated with reduced or abnormal T-cell (or monocytic) function and number, mainly seen in HIV patients, such as cerebral toxoplasmosis, CNS cryptococcosis, cytomegalovirus encephalitis, and progressive multifocal leukoencephalopathy. The clinical presentation, diagnostic procedures, as well as therapeutic and prophylactic management of these diseases are described in detail. The second part of the chapter deals with diseases usually seen in patients with impaired or reduced number and function of polymorphonuclear granulocytes. Such CNS infections are frequently caused by viral, bacterial, or fungal pathogens and are described in their clinical presentation, their diagnostic procedures and the best possible therapeutic and prophylactic management.

Update on immunizations in solid organ transplant recipients: what clinicians need to know

Vaccine-preventable diseases remain a major source of morbidity and mortality in transplant recipients. Since the publication of the American Society of Transplantation's guidelines for vaccination of solid organ transplant recipients in 2004 (1), several new vaccines have been licensed. Transplant clinicians have been inundated by questions from patients and colleagues regarding the utility and safety of these vaccines in transplant candidates and recipients. In addition, new data has appeared regarding utility of some established vaccines, lack of rejection after vaccination and newer adjuvant strategies. Literature published between 2004 and 2007 was reviewed in a Medline search. Guidelines from the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices are reviewed and summarized, with particular attention to vaccines for human papillomavirus, varicella and varicella-zoster, tetanus-reduced diphtheria-acellular pertussis (Tdap) and hepatitis B, as well as conjugated meningococcal and conjugated pneumococcal vaccines. Although randomized controlled trials in transplant recipients have not been performed for most new licensed vaccines, preliminary recommendations can be formulated based on current data and guidelines. Further studies will be important to determine the indications and optimal timing of newer immunizations and immunization strategies.