The enhancing effect of Klebsiella pneumoniae lysate on cellular immunity

Abstract

Cellular immunity plays important roles in clearing intracellular pathogens or tumor cells. It is of significance to develop an adjuvant able to efficaciously induce cellular immunity, but such an approved adjuvant is not currently available. Klebsiella pneumoniae ( K. pneumoniae) possesses lipopolysaccharide and capsular polysaccharide, both of which have been demonstrated to be able to induce humoral immunity. In this study, we investigated the effect of K. pneumoniae on epidermal cellular immunity, in vitro. The effects of K. pneumoniae on the maturation of Langerhans cells (LCs), the capacity to induce T-cell proliferation, and the secretion of interferon gamma (IFN-γ) by T cells were examined. The results showed that K. pneumoniae induced significant upregulation of CD86 and human leukocyte antigen-deterodimer (HLA-DR) levels on LCs, but not CD40 and CD80. K. pneumoniae-loaded LCs induced significant CD4+ and CD8+ T-cell proliferation. Significant increases in extracellular IFN-γ secretion by CD4+ and CD8+ T cells stimulated with K. pneumoniae-pulsed LCs using enzyme-linked immunospot assay (ELISPOT) were demonstrated, while only a part of the subjects showed increases in intracellular secretion of IFN-γ using intracellular staining assay. In sum, K. pneumoniae has the potential to enhance epidermal cellular immunity and may act as a potential adjuvant in intradermal vaccines designed to enhance cellular immunity.