Vol 44 # 4 December 2012 - Kma.org.kw

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Synergy between Dendritic Cell-Based Vaccine and Anti-CD137 Monoclonal ...
December 2012
Fig. 1: Phenotype of dendritic cells. The dendritic cells were cultured as described in the methods. Immature and mature dendritic cells
were harvested, stained with fluorescein isothiocyanate-labeled anti-CD11c (dendritic cell marker) monoclonal antibody and phycoerythrinlabeled
anti-CD83 (maturation marker of dendritic cells) monoclonal antibody, and then analyzed by flow cytometry. Expression rates of
CD11c and CD83 in unpulsed dendritic cells (i.e., immature dendritic cells) and Renca tumor lysate-pulsed dendritic cells (i.e., mature
dendritic cells) were 85.9% (i.e., 3.6% + 82.3%) and 3.6%, and 87.1% (i.e., 71.5% + 15.6 %) and 71.5%, respectively.
dendritic cells (i.e., mature dendritic cells) expressed
higher level of CD83 (maturation marker of dendritic
cells), compared with unpulsed dendritic cells (i.e.,
immature dendritic cells).
Tumor lysate-pulsed dendritic cells up-regulate
CD137 expression on T cells
CD137 expression on T cells was measured before
and after stimulation of T cells with Renca tumor
lysate-pulsed dendritic cells. As shown in Fig. 2,
unstimulated T cells showed low expression of CD137.
At three days after stimulation with Renca tumor
lysate-pulsed dendritic cells, T cells increased the
expression of CD137.
Anti-CD137 antibody potentiates the anti-tumor
efficacy of tumor lysate-pulsed dendritic cells
We tested the anticancer effect of tumor lysatepulsed
dendritic cells and anti-CD137 antibody, alone
or in combination, in the subcutaneous Renca tumor
mouse model. As shown in Fig. 3, tumor lysate-pulsed
dendritic cells or anti-CD137 antibody treatment
significantly suppressed tumor growth compared
with control (untreated) group (p < 0.05). However,
the combination therapy with tumor lysate-pulsed
dendritic cells and anti-CD137 antibody resulted in
the greatest inhibition of tumor growth (p < 0.05),
indicating a synergistic anticancer effect of the
combined treatment.
Combination of tumor lysate-pulsed dendritic
cells with anti-CD137 antibody augments T-cell
proliferation
T cells isolated from splenocytes of control
and differently treated mice were assayed for cell
proliferation in response to Renca tumor lysate-pulsed
dendritic cells. As shown in Fig. 4, mice treated with
tumor lysate-pulsed dendritic cells or anti-CD137
antibody alone showed a significant increase in T-cell
proliferation, compared with control group (p < 0.05).
However, co-administration of tumor lysate-pulsed
dendritic cells with anti-CD137 antibody resulted in
stronger cell proliferation than any other groups (p <
0.05).
Combination therapy improves cytotoxic T-
lymphocyte activity
CD8 + T cells isolated from splenocytes of control
and differently treated mice were stimulated in vitro by
co-culture with Renca tumor lysate-pulsed dendritic
cells and analyzed for cytotoxic T-lymphocyte activity.
The cytotoxic T-lymphocyte activity in tumor lysatepulsed
dendritic cells or anti-CD137 antibody-onlytreated
mice was significantly increased in comparison
with control (untreated) mice (p < 0.05) (Fig. 5). The
combination treatment with tumor lysate-pulsed
dendritic cells and anti-CD137 antibody caused a
much higher cytotoxic T-lymphocyte activity than
either monotherapy (p < 0.05) (Fig. 5).