The early peak of IFN-γ in the serum of P. yoelii -infected mice is dependent on T and/or B lymphocytes, but independent of CD1d-dependent NKT cells. B6.RAG2-/- mice and B6.CD1d-/- mice were infected with 4,000 sporozoites of P. yoelii 265BY and the serum level of IFN-γ at days 0 and 5 p.i. was determined by ELISA. Results from a pool of 2 to 3 independent experiments per mouse strain (4 to 17 mice per time point) are shown. Individual values (circles) and mean values (bars) are shown. The statistical difference between day 0 (n = 8 B6.CD1d-/-) and day 5 p.i. (n = 10 B6.CD1d-/-) was calculated with the Mann-Whitney test.