Induction of differentiation of hematopoietic cells by the vaccine adjuvants (75.10)

Abstract

Abstract Vaccine adjuvants have been used to enhance the immune responses against the co-administered antigens. The mechanisms of action by the adjuvants however remain poorly understood. We attempt to investigate in this study the effect of vaccine adjuvants on differentiation of the hematopoietic system. C57BL/6J mice were vaccinated with ovalbumin (OVA) in L121-adjuvant, an emulsion adjuvant consists of Pluronic L121 that previously shown to stimulate cytotoxic lymphocyte (CTL) effect. Cells were isolated from bone marrow and thymus after vaccination, followed by flow cytometric analysis. Our data showed that treatment of animals with L121-adjuvant skewed the differentiation of hematopoietic cells, resulting in a significant increase of the CD11b+ population at the expense of lineage (lin)+ cells, attributing mainly to a dramatic reduction of the B220+ population. A considerable increase of Lin-/Sca1+/c-Kit+ (LSK) hematopoietic stem/progenitor cells was observed in the bone marrow of immunized mice, suggesting an induction of enhanced cell expansion by the vaccine adjuvant. Treatment of animals with L121-adjuvant also affects the differentiation of cells in the thymus with a decrease of the CD4+/CD8+ double-positive (DP) cells, and a concurrent increase of the CD4+ and CD8+ single positive (SP) populations. These experimental results suggested the differentiation effect of vaccine adjuvants on the hematopoietic system, accounting for the enhanced immunity after immunization.