Imaging Techniques Can Help Assess Immune System Recovery in HIV-Infected Patients

July 13, 2018

The results of an animal study suggest that a non-invasive imaging technique could, with development, become a useful tool for assessing the immune system's recovery at home. people receiving treatment for HIV infection. The researchers used SPECT (Single Photon Emission Computed Tomography) and a CD4-specific imaging probe to evaluate immune system changes in the bodies of macaques infected with SIV, a simian form of HIV, after the disease. initiation and interruption of antiretroviral therapy. They evaluated pools of CD4 + T cells, the main cell type that HIV infects and destroyed, in tissues such as lymph nodes, spleen and intestine.

Their results show that CD4 + T cell levels in the blood The health of the system in people living with HIV often does not fully reflect the situation in the tissues. A low level of CD4 + T cells indicates an immune system weakened by HIV, and the level generally increases when antiretroviral therapy is started and the immune system begins to recover. The new research, led by scientists from the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, defines the complexity of the immune recovery process at different tissue levels.

SPECT imaging chronic data from seven SIV-infected monkeys revealed that the timing of reconstitution of the CD4 + T cell pool in the months following ART initiation varied between animals and between groups of lymph nodes in the same animal. In addition, reconstitution of CD4 + T lymphocyte pools in the lymph nodes of animals receiving long-term ART appeared suboptimal; they remained smaller than the pools observed in healthy control animals. Pools of CD4 + T cells in the spleen appeared similar in both groups

Scientists also evaluated changes in CD4 + T cell pools in the intestine, which are considered a major target for HIV infection. In contrast to observations in the lymph nodes and spleen, the researchers found little difference in intestinal CD4 + T cell pools between healthy and visually infected animals, challenging the idea that 39, intestine is the main target of infection with SIV. In the future, the extension of this imaging technology to humans could help scientists evaluate immune reconstitution after standard and experimental anti-HIV treatments, the authors conclude.