This is in contrast to the majority of healthy siblings who experienced seroconversion, even in the context of seroprotective titers at the time of enrollment. rates of antibody seroprotection and seroconversion that were similar to those achieved by their healthy siblings. However, for both influenza strains, IFN- 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. MCL-1/BCL-2-IN-3 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- responses are predictive of efficacy and to identify the optimal vaccination strategy to protect populations with a high risk of infection. Recent outbreaks of severe acute respiratory syndrome and avian influenza demand optimized strategies to protect society from pandemic respiratory illnesses [1, 2]. Of particular concern is the population of solid organ transplant recipients. These individuals are at high risk for morbidity and mortality secondary to influenza, and their immune response to vaccination is poorly understood. Pediatric transplant recipients are, perhaps, the most vulnerable, because even immunocompetent children are susceptible to serious influenza disease [3, 4]. At the time of transplantation, infants and young children often lack prior exposure to influenza and its subsequent protective immunologic priming . Pediatric solid organ transplant recipients are at risk for influenza-related complications, including pneumonia, sepsis, CNS disease, acute graft rejection, and death [6C8]. Inside a retrospective review including 42 pediatric solid organ transplant recipients with influenza or parainfluenza, 3 individuals with influenza died and 4 developed concurrent infections with cytomegalovirus (CMV) and bacteremia . Liver transplant recipients represent a MCL-1/BCL-2-IN-3 growing proportion of the population of pediatric transplant recipients. How these children Rabbit Polyclonal to EPHA3/4/5 (phospho-Tyr779/833) respond to vaccinations, including the inactivated trivalent subvirion influenza vaccine, is poorly understood. Evaluations of the inactivated influenza vaccine in additional immunocompromised populations, MCL-1/BCL-2-IN-3 such as children with HIV illness and malignancy, suggest a diminished response to the vaccine that is relative to immunocompetent children [9, 10]. However, the data concerning the immune response in pediatric solid organ transplant recipients are less substantial. Prior studies possess yielded conflicting results, with some authors suggesting a diminished antibody response to vaccination [11C13]. The generation of serum antibodies following influenza vaccination is vital for safety from illness and is an important correlate for vaccine effectiveness [5, 14]. However, clearance of influenza and prevention of influenza-associated complications also require a strenuous cell-mediated immune response. Influenza-specific CD8+ T cells mediate the killing of infected sponsor cells and up-regulate proinflammatory cytokines in animal models [15, 16]. Adults with baseline cytotoxic T cell immunity against influenza obvious virus more effectively than those with no pre-existing cell-mediated immunity, and cytotoxic T cells may demonstrate cross-reactivity when responding to fresh influenza A computer virus subtypes . Influenza in babies stimulates cytotoxic T lymphocyte proliferation, although the degree of this response may not correlate with serum hemagglutination inhibition (HI) antibody levels . Following vaccination, secondary antibody response requires the growth of memory CD8+ T cells and CD4+ T cell assistance [19C21]. Although small studies including both pediatric hematopoietic stem cell transplant recipients and adult solid organ transplant recipients suggest a diminished T cell response to inactivated influenza vaccine [22, 23], to our knowledge, no prospective studies have evaluated this response in pediatric solid organ transplant recipients. We present the results of a single center, prospective, comparative evaluation of humoral.