Genotypic Confirmation of Transimmunization-Induced Dendritic Cell Maturation
Transimmunization (TI), a novel modification of the widely used immunotherapy extracorporeal
photopheresis (ECP), induces conversion of processed monocytes into cells expressing
phenotypic and functional features of dendritic antigen presenting cells (DC). To further
characterize TI-induced DC, we analyzed differential gene expression in the monocyte/DC
population after TI treatment. Because ECP, the therapy upon which TI is based, has the unique
capacity to induce both anti-cancer immune responses in cutaneous T cell lymphoma (CTCL)
patients and tolerogenic responses in graft-versus-host disease (GVHD), we studied TI-induced
gene expression changes in both of these patient populations as well as in healthy normal control
individuals with the goal of fully characterizing the gene expression profile(s) induced by TI.
Peripheral blood leukocytes from 6 patients (3 patients with CTCL and 3 patients with GVHD)
were procured prior to ECP, immediately after ECP, and following TI processing, and were then
enriched for monocytes/DC. RNA was extracted and gene expression compared using
Affymetrix total human genome microarrays to analyze 39,000 genes. Differential gene
expression was considered as a ¡Ý 2-fold change and P-value ¡Ü0.05. TI induced significant upregulation
of genes associated with DC maturation including: DC-LAMP, CD80, CD40, and
Decysin. In addition, TI induced down-regulation of monocyte genes such as CD33 and CD36.
These changes in gene expression were seen in both CTCL and GVHD patients, suggesting that
TI is capable of mediating DC differentiation regardless of disease process. However, some
genes (e.g. IL-19, Tryptophan 2,3-dioxygenase) were differentially expressed after TI only in
GVHD patients, while others, (e.g. heat-shock proteins 70, 27, and 40) were differentially
expressed only in CTCL patients. Our microarray findings were confirmed by quantitative realtime
PCR on patient samples as well as on samples from healthy normal controls that underwent
the TI procedure. Analysis of the microarray data using GeneGo pathway analysis software
demonstrated that the chemokines and adhesion signaling pathway was significantly involved in
the mechanism of both ECP and TI, suggesting a crucial role for cell adhesion in these therapies.
Taken together, our gene expression and pathway data suggest that TI activates specific signaling
cascades that lead to activation and up-regulation of mature DC genes. Our results support the
use of TI as a method of generating mature dendritic cells for immunotherapy.
School Location:USA - Connecticut
Source Type:Master's Thesis
Keywords:immunotherapy adoptive photopheresis humans graft vs host disease lymphoma t cell cutaneous dendritic cells
Date of Publication:02/23/2009