By Johnathan Nieves ’11
Cells known as regulator T cells are being implicated in limiting the effectiveness of therapeutic vaccines for HIV by suppressing the immune system. This new knowledge may help researchers when developing future HIV vaccines.
Our immune system may be a little dumber than we thought. Cells involved in the body’s immune system are being implicated in limiting the effectiveness of therapeutic vaccines for HIV. A recent study published in the journal PLoS ONE on March 24th, demonstrated that regulatory T cells are involved in reducing the effectiveness of HIV vaccines by suppressing the immune system. The findings of the study may help researchers improve the effectiveness future therapeutic HIV vaccines.
Regulatory T cells (Treg) are important because they prevent the body’s immune system from attacking itself. When the immune system attacks itself, it is the result of it mistaking a non-harmful entity, like a liver cell, for a harmful one. The non-harmful entity is then tagged for destruction and the body’s immune system would destroy it and anything similar to it. This is known as an auto-immune response. Without Treg, autoimmune diseases could flourish.
So what if Treg cells are suppressing the immune system so that novel therapeutic HIV vaccines cannot be recognized and targeted for destruction? University of Pittsburgh health science researchers sought to answer this question as a follow-up to an HIV vaccine they developed and tested in 17 HIV positive patients in 2008 that produced unsatisfying results. In the study the researchers removed Treg cells from the patients’ blood samples to see what effect the HIV vaccine would have on the sample in the absence of Treg. To their surprise they found that Treg reduced the patients’ immune system’s ability to recognize the HIV vaccine and begin to target the actual HIV virus in the patients blood.
“When we removed Treg from blood cells, we found a much stronger immune response to the vaccine, giving us insight into how we can develop more effective HIV vaccines,” said Charles R. Rinaldo, Jr., Ph.D., the study’s lead author. “Treg normally shuts down [the immune response] once the infection has been controlled, but in this case it appears to be [suppressing the immune response] early and possibly limiting the vaccine’s ability to do its job effectively.”
One theory is that the HIV infection itself is responsible for increasing Treg levels in the blood which in turn results in the immune systems inability to recognize the HIV virus.
“We know how to treat HIV, but are still learning how to use immunotherapy strategies to completely flush it out of the body,” added Bernard J.C. Macatangay, M.D., co-author of the study. “Our findings show Treg plays an important role, but we need to figure out how to maintain the right balance by getting around these cells without blocking them completely.”
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