It is likely that dendritic cells are a key mediator of vaccine function. Dendritic cells
activate T-cell responses by capturing, processing and presenting antigens in the context
of MHC molecules to T lymphocytes.
In addition, dendritic cells express the costimulatory molecules B7-1 (CD80) and B7-2
(CD86), which provide a second signal on interaction with their receptors on the surface
of T cells known as CD28 and CTLA-4. Engagement of CD28 is associated with
proliferation and differentiation whereas CTLA-4 may trigger functional
unresponsiveness. Blocking CTLA-4 engagement has been reported to enhance immune
responses to tumor cells.
Activating T cells by dendritic cells is thus accomplished by presenting antigen/ MHC
complexes in the context of a variety of other activating signals. Dendritic cells undergo
maturation or super activation through the activity of GM-CSF and TNF- and other
macrophage derived cytokines, greatly enhancing their ability to activate naive T cells. In
addition, CD40 and its ligand have been shown to be important in B cell activation, in the
production of Type I cytokines by T-helper cells, and in the generation of cytotoxic T-
cell memory responses.
Research have shown that the addition of CD40 L trimer to DNA vaccination can
significantly increase antitumor efficacy. Another molecule called FLT3 ligand can
induce the apparent growth and differentiation of functional dendritic cell and has been
reported to have antitumor effects and its effect on the function of recombinant and
synthetic anticancer vaccines is the subject of a great deal of investigation in
experimental mouse model.
Bancherean J, Steinman RM. Dendritic cells and the control of immunity. Nature 1998; 392:245
Bluestone JA. Cell fate in the immune system: decisions, decisions, decisions. Immunol Rev
Bronte V, Carroll MV, Goletz TJ, et al. Antigen expression by dendritic cells correlates with the
therapeutic effectiveness of a model recombinant poxvirus tumor vaccine. Proc Natl Acad Sci
USA 1997; 94: 3183
Leach DR, Krummel MF, Allison JP. Enhancement of antitumor immunity by CTLA-4
blockade. Science 1996; 271:1734
Van Parijis L, Abbas AK. Homeostasis of self-tolerance in the immune system: turning
lymphocytes off. Science 1998; 280:243
ABOUT THE AUTHOR
I’m a Postgraduate student at the University of Ghana-Legon studying MPhil Biochemistry.
Before beginning my postgraduate studies, I completed a BSc in Biochemistry at the University
for Development Studies- Tamale.
Moving forward I took up the role of a research assistant at Center for Plant Medicine Research
where I have the chance to research on safety analysis of herbal drugs and efficacy studies of
I have varying interests from bioinformatics and sequencing technology to cancer genetics. My
aim is to improve my knowledge and scientific acumen with further education and experience.
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