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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: ADP-ribosyl Cyclase 1, Antigens, CD, Apoptosis Regulatory Proteins, CD8-Positive T-Lymphocytes, Case-Control Studies, Cell Differentiation, HIV Infections, Herpesvirus 4, Human, Humans, Lymphocyte Activation, Programmed Cell Death 1 Receptor.
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Does pD-1 expression on human CD8 T cells depend on both state of differentiation and activation status? Context: PD-1 expression on HIV-specific CD8 T cells was recently reported to reflect functional exhaustion, resulting in uncontrolled HIV-1 replication. Assessing PD-1 expression on T cells may be highly relevant in T-cell immunology and vaccine monitoring. However, this requires us to gain further insights into the significance of PD-1 expression on CD8 T cells in humans. We performed a detailed analysis of PD-1 expression pattern on various CD8 T cell subsets from healthy or HIV infected donors. PD-1 expression has two facets in vivo. On the one hand, it is linked to T-cell differentiation: PD-1 is up-regulated on early/intermediate differentiated subsets, which include HIV and Epstein-Barr virus-specific CD8 T-cell populations, but is down-regulated during late stages of differentiation. On the other hand, it is linked to T-cell activation: on PD-1 positive cells, PD-1 over-expression occurs along with the up-regulation of activation markers such as CD38 or HLA-DR.
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PD-1 expression on CD8 T cells, including those specific for HIV, can be related both to their differentiation stage and their activation status. It is important to consider these findings when assessing the expression of PD-1 on T cells. Final Decision: yes