Study: Memory CD8+ T cells are more resistant to apoptosis than naive cells.

2002 DEC 11 - (NewsRx.com & NewsRx.net) -- Emory University vaccine researchers have demonstrated, in mice, that naive and memory CD8+ T cells have differing sensitivities to apoptosis. They think their findings may be applicable to designing prime/boost vaccine strategies.

"Apoptosis is a critical regulator of homeostasis in the immune system. In this study we demonstrate that memory CD8+ T cells are more resistant to apoptosis than naive cells," said J.M. Grayson and colleagues.

"After whole body irradiation of mice, both naive and memory CD8+ T cells decreased in number, but the reduction in the number of naive cells was eightfold greater than that in memory CD8+ T cells," the researchers reported.

They also "analyzed the expansion and contraction of naive and memory CD8+ T cells in vivo following exposure to Ag [antigen]."

"We found that memory CD8+ T cells not only responded more quickly than naive cells after viral infection, but that secondary effector cells generated from memory cells underwent much less contraction compared with primary effectors generated from naive cells (3- to 5-fold vs. 10- to 20-fold decrease)," wrote Grayson and colleagues.

"Increased numbers of secondary memory cells were observed in both lymphoid and nonlymphoid tissues. When naive and memory cells were transferred into the same animal, secondary ...