Table III.

Proliferation of exosome-responsive CD4+ T cells to secondary antigenic stimulation with gB vs pp65. ^c

Secondary Stimulation	% BrdU positive
No Antigen	3.8
gB	12.8
pp65	3.6

^cPositively isolated CD4+ T cells prelabeled with CFSE were cultured with autologous monocytes and purified exosomes from CMV-infected HUVEC. CFSElow CD4+ cells were collected by cell sorting, rested and restimulated with autologous monocytes and the purified antigens indicated as described in the Methods. CD4+T cell proliferation in response to restimulation was measured by BrdU incorporation. Two of 2 other experiments of slightly different design also showed priming by exosomes to gB.