Longevity of B-Cell and T-Cell Responses After Live Attenuated Influenza Vaccination in Children

Abstract

Background. The live attenuated influenza vaccine (LAIV) is the preferred vaccine for children, but the mechanisms behind protective immune responses are unclear, and the duration of immunity remains to be elucidated. This study reports on the longevity of B-cell and T-cell responses elicited by the LAIV.Methods. Thirty-eight children (3–17 years old) were administered seasonal LAIV. Blood samples were collected before vaccination with sequential sampling up to 1 year after vaccination. Humoral responses were evaluated by a hemagglutination inhibition assay, and memory B-cell responses were evaluated by an enzyme-linked immunosorbent spot assay (ELISpot). T-cell responses were evaluated by interferon γ (IFN-γ) ELISpot analysis, and intracellular cytokine staining of CD4+ T cells for detection of IFN-γ, interleukin 2, and tumor necrosis factor α was performed using flow cytometry.Results. LAIV induced significant increases in B-cell and T-cell responses, which were sustained at least 1 year after vaccination. Strain variations were observed, in which the B strain elicited stronger responses. IFN-γ–expressing T cell counts increased significantly, and remained higher than prevaccination levels 1 year later. Expression of T-helper type 1 intracellular cytokines (interleukin 2, IFN-γ, and tumor necrosis factor α) increased after 1 dose and were boosted after the second dose. Hemagglutination inhibition titers were sustained for 1 year. Vaccine-induced memory B cell counts were significantly increased, and the response persisted for one year.Conclusions. LAIV elicited B-cell and T-cell responses that persisted for at least 1 year in children. This is a novel finding that will aid future vaccine policy.

Humoral, T-cell and B-cell immune responses to seasonal influenza vaccine in solid organ transplant recipients receiving anti-T cell therapies

“…PBMCs were then washed, counted and frozen in fetal bovine serum (FBS) containing 10% dimethyl sulfoxide (DMSO) at −80 • C overnight and then transferred to liquid nitrogen until use. Lymphocytes were defrosted and rested overnight in RPMI medium with 10% fetal calf serum at 37 • C. T-cell responses were assessed by detecting IFN-␥ production, after stimulation with the 3 viral strains, using a standard ELISpot assay [22][23][24]. Briefly, cells (400,000 cells/well) in RPMI medium with 10% fetal calf serum were cultured on a pre-coated IFN-␥ plates (Mabtech AB, Sweden) with negative control (medium alone) or influenza antigens (5 g/ml of split virus vaccine of each influenza strain A/H1N1, A/H3N2, B strain).…”

“…PBMC were stimulated overnight with a mixture of the three split virus antigens in the vaccine, A/H1N1, A/H3N2 and B (2.5 g/ml of each protein) in the presence of Brefeldin A, Monensin and anti-CD49d antibodies (BD Biosciences, USA). After ovenight stimulation, cells were stained for intracellular cytokines and analyzed on a BD LSRFortessa (BD Biosciences) for the expression of IFN-␥, IL-2 and TNF-␣ from CD4 + T-cells [24,25]. CD4 + T cells were classified on the basis of IFN-␥, IL-2, and TNF-␣ secretion as single producers (producing any single cytokine), double producers (2 cytokines), and triple producers (all 3 cytokines).…”

The expression of B & T cell activation markers in children's tonsils following live attenuated influenza vaccine

“…Recently, we reported the systemic effect of the LAIV vaccine in a larger cohort including the children in the present study. 21 We found that LAIV elicited elevated B and T cell responses in these young children, persisting for 1 year after vaccination, with the highest responses observed against the B strain and the lowest to the Influenza A H1N1 strain. Our study has a high number of young children and is particularly unique in the collection of tonsils after vaccination allowing us to evaluate the local immune response in the upper airways.…”

“…Serial dilutions of serum samples, 8 Hemagglutinating units of the homologous H1N1 and H3N2 vaccine strains and 0.7% turkey red blood cells were employed to measure the serum HI titers following standard procedure. 21,22 Tonsil tissue preparation and RNA isolation A sectioned palatine tonsil (2 £ 10 £ 10 mm) was submerged in PAXgene Ò Blood RNA Tube reagent (PAXgene Blood RNA kit, PreAnalytiX GmbH, Hombrecht, Germany), in order to stabilize intracellular RNA by inhibiting Ribonuclease (RNase) activity and preserve ex-vivo gene expression. Lysing matrix D (MP Biomedicals, Santa Ana, California, USA) and small ceramic beads were added to the tissue and shaken for 30 seconds before storage at ¡20 C. Total RNA isolation was performed using the PAXgene Tissue RNA kit (PreAnalytiX GmbH, Hombrecht, Germany), according to the manufacturer's instructions.…”

Impact of Type I Interferon on the Safety and Immunogenicity of an Experimental Live-Attenuated Herpes Simplex Virus 1 Vaccine in Mice

“…Advantages of live-attenuated vaccines as demonstrated here include the activation of all phases of the immune system to generate robust humoral and cellular immune responses with antigenic breadth similar to that induced by natural infection and likely the enhanced longevity of protection in children and adolescents with no previous exposure to HSV. Moreover, live-attenuated influenza vaccines have emerged as the preferred vaccines in this age group in comparison to the trivalent inactivated vaccine, and this preference is attributed to the inferior performance of inactivated vaccines in children not previously infected with the influenza virus (77). On the other hand, concerns of genetic reversion of attenuated pathogens and their enhanced virulence in immunocompromised patients are evident.…”