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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, METHODS, RESULTS. Meshes: Adult, CD4 Lymphocyte Count, CD4-Positive T-Lymphocytes, CD8-Positive T-Lymphocytes, Cell Death, Cell Division, Flow Cytometry, HIV Infections, HIV-1, Humans, Immunologic Memory, Lymphocyte Activation, Lymphocyte Count, Prospective Studies, Receptors, CCR5, Receptors, CXCR4, Statistics, Nonparametric, T-Lymphocyte Subsets, T-Lymphocytes, Regulatory, Tumor Necrosis Factor Receptor Superfamily, Member 7, Viral Load.
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Does depletion of naive CD4 T cells by CXCR4-using HIV-1 variants occur mainly through increased T-cell death and activation? Context: Using SCID-Hu mice models and in vitro culture systems, it has been shown that syncytium inducing/CXCR4 using (X4) HIV-1 variants affect thymic function through infection and killing of CXCR4 thymocytes. The effect of X4-emergence on naive, memory and effector T-cell subset kinetics in vivo is, however, not known. Prospective cohort study. Analysis of changes in naive, memory and effector CD4 and CD8 T-cell numbers and cell division before and after the emergence of X4 variants. Significantly lower numbers of CD4 T cells in patients with X4 variants (n = 18) compared to patients with non-syncytium inducing/CCR5 using variants (n = 74) were due to increased loss of naive and CD27 memory CD4 T cells. In addition, emergence of X4 variants was associated with a small but significant decline in naive CD8 T-cell numbers and increased proportions of dividing CD4 and CD8 naive, memory and effector T cells.
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Loss of naive T cells may suggest thymic dysfunction, however, such an effect would explain only part of the accelerated naive CD4 T-cell decline because of the longevity of naive T cells. Our data suggest that the accelerated naive CD4 T-cell decline induced by X4 variants is caused mainly by increased death and recruitment to the memory compartment of these cells. Final Decision: yes