Gastrointestinal epithelium is an early extrathymic site for increased prevalence of CD34(+) progenitor cells in contrast to the thymus during primary simian immunodeficiency virus infection

The objective of this study was to determine the effects of primary simian immunodeficiency virus (SIV) infection on the prevalence and phenotype of p rogenitor cells present in the gastrointestinal epithelia of SIV-infected r hesus macaques, a primate model for human immunodeficiency virus pathogenes is, The gastrointestinal epithelium was residence to progenitor cells expre ssing CD34 antigen, a subset of which also coexpressed Thy-1 and c-kit rece ptors, suggesting that the CD34(+) population in the intestine comprised a subpopulation of primitive precursors, Following experimental SIVmac251 inf ection, an ear ly increase in the proportions of CD34(+) Thy-1(+) and CD34( +) c-kit(+) progenitor cells was observed in the gastrointestinal epitheliu m, Tn contrast, the proportion of CD34(+) tells in the thymus declined duri ng primary SIV infection, which was characterized by a decrease in the freq uency of CD34(+) Thy-1(+) progenitor cells. A severe depletion in the frequ ency of CD4-committed CD34(+) progenitors was observed in the gastrointesti nal epithelium 2 weeks after SIV infection which persisted even 4 weeks aft er infection. A coincident increase in the frequency of CD8-committed CD34( +) progenitor cells was observed during primary SIV infection. These result s indicate that in contrast to the primary lymphoid organs such as the thym us, the gastrointestinal epithelium may be an early extrathymic site for th e increased prevalence of both primitive and committed CD34(+) progenitor c ells. The gastrointestinal epithelium may potentially play an important rol e in maintaining T-cell homeostasis in the intestinal mucosa during primary SIV infection.