γδ+ T cells preferentially respond to live rather than killed malaria parasites

Abstract

We have compared the in vitro responses of peripheral blood T cells from malaria-unexposed donors to live Plastnodium falciparum schizonts, freeze- thawed schizont extracts (P. falciparum schizont extracts [PfSE]), and parasite culture supernatants. We show that the cells responding to PfSE and parasite culture supernatants are predominantly CD4+ TCRαβ+ while in the presence of live schizonts there is an additional activation of TCRγδ+ cells. Activation of TCRγδ+ cells in response to PfSE was seen only when irradiated autologous feeder cells or recombinant interleukin-2 (IL-2) was added to the cultures. Live schizonts but not PfSE induced significant IL-2 production in vitro in the first 5 days after stimulation, suggesting that induction of early IL-2 by live parasites may contribute to the marked activation of the TCRγδ+ population.