The implications for malaria vaccine programs if memory T cells from non-exposed humans can respond to malaria antigens.

Although the goal of current candidate vaccines is to expand a population of malaria antigen-specific lymphocytes, accumulating evidence suggests that peripheral blood of adult humans contains significant numbers of malaria-specific T cells prior to any exposure to vaccine or actual infection. The reason why such naive humans are susceptible to malaria infection may thus relate not to inadequate T-cell surveillance but to some other factor--possibly lack of suitable splenic modification. It is possible that current vaccine programs are misdirected because these other factors are not being addressed. The possibility of an attenuated vaccine should be re-examined.