Cancer 'turns off' important immune cells, complicating experimental vaccine therapies

A research report published in the September 2012 issue of the Journal of Leukocyte Biology offers a possible explanation of why some cancer vaccines are not as effective as hoped, while at the same time identifies a new therapeutic strategy for treating autoimmune problems. In the report, scientists suggest that cancer, even in the very early stages, produces a negative immune response from dendritic cells, which prevent lymphocytes from working against the disease. Although problematic for cancer treatment, these flawed dendritic cells could be valuable therapeutic tools for preventing the immune system from attacking what it should not, as is the case with autoimmune disorders and organ transplants.

"Immunotherapy of cancer has been an elusive research target that, though promising, never seems to 'get there,'" said José Alexandre M. Barbuto, Ph.D., from the Laboratory of Tumor Immunology, Department of Immunology, Institute of Biomedical Sciences at the University of São Paulo, in São Paulo, Brazil. "This study helps us to better understand the mechanisms by which tumors avoid immune recognition and rejection and may, therefore, teach us how to actually engage effectively the immune system in the fight against tumors, thus achieving much better clinical responses and, consequently, quality of life, in our therapeutic approaches."

To make this discovery, researchers obtained a small sample of blood from , and from healthy volunteers. The blood cells were then separated and induced to become dendritic cells. Researchers then used these laboratory-generated dendritic cells to induce responses from other , namely lymphocytes. While dendritic cells from the healthy donors induced vigorous lymphocytic responses, from cancer patients induced mainly the activation of a specific type of lymphocyte, a regulatory lymphocyte that works as a "brake" for other types of lymphocytes.

"Understanding why the immune system does not recognize and eliminate cancer is critical to developing effective immunotherapies to fight the disease," said John Wherry, Ph.D., Deputy Editor of the . "Immunologists have been trying to unravel the answer to this question for decades and have realized that the problem is both on the immune system side, and because cancer cells appear to actively 'fly under the radar' avoiding immune system detection. This article offers insights into the underlying mechanisms regulating a key immune cell type, the dendritic cell, involved in initiating anti-tumor responses."

More information: Rodrigo Nalio Ramos, Lilian Sally Chin, Ana Paula S. A. dos Santos, Patrícia Cruz Bergami-Santos, Fábio Laginha, and José Alexandre M. Barbuto. Monocyte-derived dendritic cells from breast cancer patients are biased to induce CD4+CD25+Foxp3+ regulatory T cells. J Leukoc Biol September 2012 92:673-682; doi:10.1189/jlb.0112048

add to favorites email to friend print save as pdf

Related Stories

'Super' enzyme may lead way to better tumor vaccines

Dec 04, 2006

A "super" form of the enzyme Akt1 could provide the key to boosting the effect of tumor vaccines by extending the lives of dendritic cells, the immune-system master switches that promote the response of T-cells, which attack ...

Gene that suppresses cell's immune activation identified

Mar 24, 2011

(PhysOrg.com) -- A new study of prostate tumors has shown that a gene, FOXO3, suppresses activation of cells related to immunity and thus leads to a reduced immune response against a growing cancer. One of the main ...

Skin sentry cells promote distinct immune responses

Jul 21, 2011

A new study reveals that just as different soldiers in the field have different jobs, subsets of a type of immune cell that polices the barriers of the body can promote unique and opposite immune responses against the same ...

New origin found for a critical immune response

Mar 01, 2009

An immune system response that is critical to the first stages of fighting off viruses and harmful bacteria comes from an entirely different direction than most scientists had thought, according to a finding by researchers ...

Recommended for you

Endogenous hormones improve breast cancer risk models

12 hours ago

(HealthDay)—Inclusion of endogenous hormones in prediction models improves prediction of invasive breast cancer risk in postmenopausal women, according to a study published online Aug. 18 in the Journal of ...

Novel oncogenic RET mutation found in small cell lung cancer

12 hours ago

For the first time an oncogenic somatic mutation at amino acid 918 in the RET (rearranged during transfection) protein has been identified in small cell lung cancer (SCLC) tumors and enforced expression of this mutation within ...

User comments