Submitted May 28, 2008
Accepted September 2, 2008
Intestinal double positive CD4+CD8+ T cells of neonatal rhesus macaques are proliferating, activated, memory cells and primary targets for SIVMAC251 infection
Xiaolei Wang, Arpita Das, Andrew A Lackner, Ronald S. Veazey, and Bapi Pahar*
Division of Comparative Pathology, Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA, United States
Division of Microbiology, Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA, United States
Division of Immunology, Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA, United States
* Corresponding author; email: bpahar{at}tulane.edu.
Peripheral blood and thymic double positive CD4+CD8+ (DP) T cells from neonates have been described earlier, but the function and immunophenotypic characteristics of other tissue-derived DP T cells are not clearly understood. Here we demonstrate the functional and immunophenotypic characteristics of DP cells in 6 different tissues including thymus from normal neonatal rhesus macaques (Macaca mulatta) between 0-21 days of age. In general, intestinal DP T cells of neonates have higher percentages of memory markers (CD28+CD95+CD45RAlowCD62Llow) and proliferation compared to SP CD4+ and CD8+ T cells. In addition, percentages of DP T cell increase and CD62L expression decreases as animals mature suggesting that DP cells mature and proliferate with maturity and/or antigen exposure. Consistent with this, intestinal DP T cells in neonates express higher levels of CCR5 and are the primary targets in SIV infection. Finally, DP T cells produce higher levels of cytokine in response to mitogen stimulation compared to SP CD4+ or CD8+ T cells. Collectively, these findings demonstrate that intestinal DP T cells of neonates are proliferating, activated, memory cells and are likely involved in regulating immune responses, in contrast to immature DP T cells in the thymus.
