This project's main objective is to study the role of the CD300 receptor family in the pathogenesis of the infection by human immunodeficiency virus (HIV) and viral escape mechanisms. We will use peripheral blood samples from patients chronically infected with HIV as well as from healthy donors. The samples will be collected in hospitals of the Basque Country, Spain. The experimental part will be performed at BioCruces Health research Institute-Cruces University Hospital. The expression of the CD300 receptors will be determined by flow cytometry techniques in cells from peripheral blood from patients and healthy subjects, and correlations studies will be performed with markers of chronic inflammation. It will be studied the CD300a inhibitory receptor in CD8+ T cells in great detail, with a particular emphasis on its participation in the processes of cell exhaustion, which is defined by the loss of effector functions and proliferative capacity of memory T cells. Finally, we will determine the degree of translocation of phosphatidylserine and phosphatidylethanolamine, the two ligands of the CD300a inhibitory receptor, into the outer leaflet of the plasma membrane in HIV-infected cells, and their involvement in the functional recognition by HIV specific CD8+ T cells and by NK cells. We will use recombinant viruses to infect cell lines and primary cells. We believe that the results that we will obtain can be of prognostic value and it will help to identify new targets for the treatment of this disease.