Completely protected subjects had significantly higher proportions of CD4 T cells expressing the degranulation marker CD107a ( OR , 8.4 ; 95 % CI , 1.5-123 ; P = .011 ) and CD8 cells producing granzyme B ( OR , 11 ; 95 % CI , 1.9-212 ; P = .004 ) after P. falciparum restimulation .