An in vitro immune response model to determine tetanus toxoid antigen (vaccine) specific immunogenicity: Selection of sensitive assay criteria

Abstract

Many vaccines employed in childhood vaccination programmes are produced by conventional techniques, resulting in complex biological mixtures for which batch-related quality control requires in vivo potency testing. Monitoring consistency via in vitro tests during the vaccine production has the capacity to replace certain of the in vivo methods. In this respect, determining vaccine antigen immunogenicity through functional immunological tests has high potential. Advances in immunology have made it possible to analyse this biological activity by in vitro means. The present study established such an in vitro test system for tetanus toxoid (TT). This measured vaccine immunogenicity through an antigen-specific secondary (recall) response in vitro, using a porcine model growing in value for its closeness to human immune response characteristics. Discrimination between the specific recall TT antigen and diphtheria toxoid (DT) was possible using both peripheral blood mononuclear cell cultures and monocyte-derived dendritic cells in co-culture with autologous specific lymphocytes. TT-specific activation was detected with highest discrimination capacity using proliferation assays, as well as IFN-gamma and TT-specific antibody ELISPOTS (measuring secreting T and B lymphocytes, respectively). These in vitro systems show a high potential for replacing animal experimentation to evaluate the immunogenicity of complex vaccines.

The porcine dendritic cell family

“…All of these express CD172a, and in a model of antigen presentation of inactivated foot-and-mouth disease virus (FMDV) to T lymphocytes the activation was dependent on the presence of CD172a + cells [40,41]. Similar results were also obtained with classical swine fever virus (CSFV) and protein antigens derived from this virus [25,42], as well as with tetanus toxoid [43]. Separating the CD172a + PBMC into a major population of CD14 + monocytes and a minor population of CD14 À cells showed that the latter contained the CD4 À blood cDC along with the CD4 + pDC ( Table 1; [40]).…”

Submicroscopic Plasmodium infection during pregnancy is associated with reduced antibody levels to tetanus toxoid

“…The immune response against TT is characterized by strong differentiation of T cells and high production of IFN‐γ after vaccination . It was determined in vitro that the TT‐specific IFN‐γ secretion was mediated exclusively by CD4 + T cells [T helper type 1 (Th1) response] . An adequate amplification of the immune response of T cells and a potent IFN‐γ production are fundamental to B cell differentiation and suitable production of anti‐TT IgG .…”

A Modular Vaccine Platform Combining Self‐Assembled Peptide Cages and Immunogenic Peptides

“…To test whether differences in uptake of functionalized SAGE affected downstream antigen‐specific responses, the proliferative ability of human PBMCs was determined after exposure to each of the three TT‐functionalized SAGEs for up to 7 d (Figure b). PBMC proliferation is indicative of a T cell response and, in this case, considered to be a CD4 + T cell response against the TT peptide, a model CD4 + T cell epitope . Experimental controls of parent SAGE, free TT peptide, and parent SAGE mixed with free TT peptide elicited low levels of cellular proliferation.…”