Discovery of a new type of immune cells involved in HIV infection

PhilippeBenaroch-AlexandreLescure_ InstitutCurie

A population of precursor cells of dendritic cells has just been discovered by Dr. Philippe Benaroch’s team. These cells appear to play a key role in HIV virus infection. 

The team of Dr. Philippe Benaroch, immunologist at Institut Curie and head of the “Myeloid cells and immunity” team at the Inserm U932 “Immunity and cancer” unit, in collaboration with the laboratory of Dr. Florent Ginhoux from the Institute of Medical Biology in Singapore, has discovered that a sub-population of immune cells in the blood has unique properties in terms of the Human Immune Deficiency (HIV) virus. These cells are precursors of dendritic cells, true sentinels of our body responsible for detecting intruders and warning the immune system so that it can destroy them. The scientists are publishing their work in the prestigious journal PNAS.

“Among the white blood cells circulating in the blood, 1% are dendritic cells, and among these, 1% are precursor cells that have recently been discovered. It is a very small population, which is why they had gone unnoticed by researchers until now,” explains Dr. Philippe Benaroch. Despite their very small number, dendritic cells play a vital role against viruses. In fact they are the only ones that effectively initiate anti-viral immune responses. But this recent work suggests that this new population of dendritic cells is vulnerable when faced with HIV.

“One of the specific features of these cells is that they express a receptor, known as SIGLEC-1, at their surface. This receptor is known to have a considerable affinity for HIV,” explains Benaroch. “They are capable of capturing the virus circulating in the blood, and becoming infected. The HIV can then spread. Furthermore, it turns out that the new viruses produced accumulate in an intracellular compartment where they appear to be protected.” The precursors of the infected dendritic cells are thus transformed into small ticking time bombs. Armed with these new viruses, the infected cells could then migrate to the lymph nodes where there are many CD4 lymphocytes, immune cells particularly targeted by HIV.

In exposing these lymphocytes to HIV, the precursors of the dendritic cells contribute to the early phases of the infection. “They contribute via the Siglec-1 receptor. This receptor could therefore constitute a new therapeutic target in the fight against HIV,” concludes Philippe Benaroch.