Modulation of dendritic cell phenotype and mobility by tumor cells in vitro

To gain new insights into the functional interaction between DC and neoplas tic cells, we have analyzed the effects of melanoma and colorectal cancer l ines on rile chemotaxis and the phenotype of monocyte-derived DC in vitro. Both types of tumor cells displayed effective chemoattractive capacity towa rds immature, but not mature DC. Furthermore, conditioned medium of discret e melanoma lines induced upregulation of CD80, CD86, MHC class I, and MHC c lass II molecules on immature DC. However, de novo expression of E-cadherin and strung upregulation of CD15 could also be detected in the absence of C D83 expression. Melanoma-conditioned DC exhibited an increased adhesion cap acity to a melanoma cell line in vitro and did not migrate in response to S LC chemokine. Tumor-infiltrating CD15(+) cells displaying DC morphology cou ld also be detected by immunohistochemistry in the original tumor specimens from which discrete melanoma cell lines under investigation were derived. Colorectal cancer cell lines, although able to chemoattract immature DC, we re apparently unable to modulate their phenotype. Altogether our results su ggest chat tumor cells can attract immature DC in vitro and, eventually, mo dulate their phenotype. As a result, DC mobility could be severely impaired . Human Immunology 62, 39-49 (2001). (C) American Society for Histocompatib ility and Immunogenetics, 2001, Published by Elsevier Science Inc.