Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Life and death as a T lymphocyte: from immune protection to HIV pathogenesis. | Journal of Biology Minireview Life and death as a T lymphocyte from immune protection to HIV pathogenesis Nienke Vrisekoop Judith N Mandl and Ronald N Germain Address Lymphocyte Biology Section Laboratory of Immunology National Institute of Allergy and Infectious Diseases National Institutes of Health 10 Center Dr MSC-18Q2 Bethesda MD 20892 USA. Contributed equally Correspondence Nienke Vrisekoop. Email vnienke@ Abstract Detailed analysis of T cell dynamics in humans is challenging and mouse models can be important tools for characterizing T cell dynamic processes. In a paper just published in Journal of Biology Marques et al. suggest that a mouse model in which activated CD4 T cells are deleted has relevance for HIV infection. See research article http content 8 10 93 T lymphocytes have a difficult existence. As mature cells they are essential for immunity to infection but in the early stages of their development in the thymus more than 90 of them fail selection for the appropriate antigen receptors and die before export to the peripheral immune system. Those that achieve maturity spend weeks months or even years circulating through the body in constant search of a foreign antigen that their antigen-specific receptor can recognize and needing continuously to compete for trophic signals necessary for their survival. Most fail to find an antigenic match and remain as small resting cells until death. A few encounter the right partner and undergo a transient bout of exponential clonal expansion only for more than 90 of these progeny to be lost by apoptosis shortly after the antigen is cleared. The remaining 10 are maintained as memory cells Figure 1 conferring lasting protection. In normal individuals the T cell population shows excellent homeostatic control with stable numbers for decades in adult humans except for intermittent bursts of expansion during infection. Moreover this homeostasis applies not only to the total number of T cells but to
