Humoral Immune Response to Influenza A(H1N1)pdm2009 in Patients with Natural Infection and in Vaccine Recipients in the 2009 Pandemic

Abstract

The 2009 pandemic H1N1 mainly affected adolescents and children, and most of the elderly in Japan escaped clinical illness. To clarify the role of humoral immunity in the infection, the time kinetics of hemagglutination inhibition (HI), neutralization (NT), and IgG subclass antibody response directed against influenza A(H1N1)pdm2009 were analyzed in three consecutive specimens obtained from 51 young adults and children (group 1) who contracted pandemic influenza and from 74 pediatric clinic employees (group 2) inoculated with pandemic monovalent vaccine. In group 1 patients, 6 and 30 patients had lower HI and NT antibody in the acute phase respectively. Thereafter, HI and NT antibody titers increased fourfold or more in 50 patients with peak response in the third specimens obtained four weeks after the onset. IgG1 in 45 patients, IgG3 in 18 patients, and IgG4 in 29 patients showed elevated responses. Forty (54%) and 70 (95%) subjects in group 2 had positive HI and NT antibodies in the prevaccination samples, with increased antibody responses in the follow-up peaking in the second specimens. Forty of those vaccinated had increased IgG1 responses peaking in the third specimens, whereas elevated IgG3 was observed in 22 recipients with the highest level in the second samples. IgG4 did not show any increase in subjects in group 2. A few participants showed an IgG2 response in both groups. An immunologically naive population contracted influenza with apparent clinical symptoms. However, already primed subjects through subclinical infection elicited the unique pattern of IgG subclass responses by vaccination, which differed from those of naive populations.

Humoral response to natural influenza infection in solid organ transplant recipients

“…Several studies have shown that immunocompetent individuals are very likely to seroconvert (82%-95%) and to have seroprotective levels of HI antibodies (93%-98%) after natural influenza infection. [26][27][28][29] In the 31 One unexpected finding we observed was that lung transplant recipients seemed to seroconvert more frequently in response to influenza A infection compared to recipients of other organs.…”

“…Several studies have shown that immunocompetent individuals are very likely to seroconvert (82%-95%) and to have seroprotective levels of HI antibodies (93%-98%) after natural influenza infection. [26][27][28][29] In the ------------------------------------------------------------------------------------------------------------------------------------------------------ Reciprocal hemagglutinin antibody titer at presentation p=0.39 Spearman`s rho = 0.12; p=0.27 immunocompromised setting, Dhédin et al compared the humoral immune response of 20 influenza A/H1N1pdm2009-infected allogeneic HSCT recipients with a cohort of HSCT recipients vaccinated with 2 doses of influenza A/H1N1pdm2009 vaccine. 30 The seroprotection rate after infection (60%) was within the range of our findings.…”

High prevalence of IgE sensitization to inactivated influenza vaccines, yet robust IgG4 responses, in a healthy pediatric population

“…Inclusion of adults and elderly persons might have affected the overall study outcome. In fact, adults were reported to lack IgG4 induction after vaccination 32 . Therefore, future studies evaluating IgE sensitization and immune responses to influenza vaccines should include adults and the elderly.…”

“…In fact, adults were reported to lack IgG4 induction after vaccination. 32 Therefore, future studies evaluating IgE sensitization and immune responses to influenza vaccines should include adults and the elderly. Second, the study was not designed to identify risk factors for vaccine‐induced anaphylaxis.…”

Natural influenza infection produces a greater diversity of humoral responses than vaccination in immunosuppressed transplant recipients

“…Influenza virus infection causes significant morbidity and occasional mortality in the solid organ transplant (SOT) population 1,2 . A key aspect of the immune response includes the development of antibodies directed against specific proteins within the influenza virus 3‐7 . Because of the immunosuppression required to avoid graft rejection, SOT recipients tend to have reduced antibody responses to both natural influenza infection and to vaccination 8,9 .…”