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Department of Immunology, University Medical Center, Utrecht, The Netherlands
The HIV-Nef protein has been implicated in generating high viral loads and T cell activation. Transgenic (tg) mice with constitutive T cell-specific Nef expression show a dramatic reduction in T cell number and highly increased T cell turnover. Previous studies in Nef tg mice attributed this T cell activation to a direct effect of Nef at the cellular level. Given the strongly reduced peripheral T cell numbers, we examined whether this enhanced T cell division might instead be lymphopenia induced. Adoptively transferred naive wild-type T cells into lymphopenic Nef tg mice showed high T cell turnover and obtained the same effector/memory phenotype as the autologous Nef tg T cells, supporting the idea that the microenvironment determines the phenotype of the T cells present. Moreover, in bone marrow chimeras from mixtures of wild-type and Nef tg bone marrow, with a full T cell compartment containing a small proportion of Nef tg T cells, Nef tg T cells kept a naive phenotype. These results demonstrate that T cell activation in the Nef tg mice is lymphopenia induced rather than due to a direct T cell-activating effect of Nef.
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1 This work was funded by Grant Number 6011 from Aids Fonds Netherlands.
2 Address correspondence and reprint requests to Dr. Kiki Tesselaar, Department of Immunology, University Medical Center, Lundlaan 6, Room KC02.085.2, 3584 EA Utrecht, The Netherlands. E-mail address: k.tesselaar{at}umcutrecht.nl
3 Abbreviations used in this paper: tg, transgenic; wt, wild type; PLN, peripheral lymph node; MFI, mean fluorescence intensity; E/M, effector/memory.
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