A research being conducted by the University of Pittsburgh has indicated that a special class of T cells may be the reason behind the limited effectiveness of HIV therapeutic vaccines. These cells seemingly do not allow the vaccine to work to its maximum level by slowing the immune system response too soon. Through this research, scientists may be able to improve upon the impact of such vaccines by developing methods to evade the braking mechanism of these cells.
Regulatory T cells, known as Treg, are significant because they avert the immune system from turning against itself by suppressing the immune response. There is a possibility of auto-immune diseases to thrive incase of the braking action not being in place of Treg. But, what would be the result incase of these cells shutting down the immune response even before a therapeutic vaccine has even had a chance to augment immunity against HIV?
The research team wanted to answer the same question as a follow-up to a clinical trial of a therapeutic dendritic cell-based HIV vaccine established to activate the CD8, or killer T cell, response. When the research was first executed in 2008, the findings offered only limited success of the vaccine in the 17 patients participating in the trial. Researchers in the current analysis, looked back upon the patients’ blood cell samples, removed Treg from the sample and discovered that it was masking a two-fold increase in immune response to HIV induced by the vaccine.
Senior scientist Charles R. Rinaldo said that, “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. Treg normally shuts down CD8 responses once the infection has been controlled, but in this case it appears to be putting on the brakes early and possibly limiting the vaccine’s ability to do its job effectively.” He adds that one theory is that HIV- infection accentuates the presence of Treg which in turn shuts down the HIV-1-specific CD8 T cell response.
Rinaldo’s colleague, scientist Bernard J.C. Macatangay comments on the research by saying that, “We know how to treat HIV, but are still learning how to use immunotherapy strategies to completely flush it out of the body.”
The research appears to show Treg playing an important role. However it is alleged to be essential for the team to find the right balance by searching for a way around these cells without blocking them completely.
The research was published in the current issue of PLoS ONE and was supported by National Institute of Allergy and Infectious Diseases.