Impaired thymopoietic potential of immature CD3–CD4+CD8– T cell precursors from SIV-infected rhesus monkeys

Immature thymocyte subpopulations were examined for their capacity to differentiate in a newly developed xenogeneic monkey–mouse fetal thymus organ culture (FTOC) system. We provide evidence for impaired precursor function of CD3–CD4+CD8– thymocytes after in vivo infection with SIVmac251 as indicated by a reduced cell number per FTOC and a lower percentage of thymocytes with more mature phenotypes. Addition of recombinant SIV glycoprotein 120 (rgp120) also resulted in a dose-dependent impairment of T cell maturation in FTOC. The data suggest that in patients infected with HIV, T cell maturation and thus replenishment of peripheral pools may be compromised as a result of intrathymic infection or circulating viral gp120.